RHEOLOGY/dev.json

{"id":0,"sentence":"The degradation mechanism proposed for PCL consists of the carbon−oxygen bond breakage to obtain an acid and an unsaturated ester (Fig. 7). 3. 4.","label":"BIODEGRAD_PROP"}
{"id":1,"sentence":"Figure 7. Mean value of the adjusted torque in the interval from 15 to 20 minutes for the neat PLA and PLA \/ PPG composites. Table 2.","label":"BIODEGRAD_POLY"}
{"id":2,"sentence":"2A, only a slight increase in the crystallinity was observed for both diameter fibers under thermal treatment. For PLA118 fibers, the crystallinity increased from an initial value of 7.","label":"BIODEGRAD_PROP"}
{"id":3,"sentence":"In Figure 1 is the comparison of the FTIR spectra in the fingerprint region of the β -, γ -, and δ−form P3HP samples with those of the amorphous P3HP one.","label":"POLY_STRUC"}
{"id":4,"sentence":"The above significant effect comes from that the PLA phase domains become much stronger when PLA crystals replace the amorphous glassy PLA in the PLA hard domains, which brings about much stiff cross−linkings in the microphase−separated triblock copolymers.","label":"BIODEGRAD_POLY"}
{"id":5,"sentence":"25 J \/ mol Ea2 0 24 504. 68 J \/ mol Ea3 0.16 300.76 J \/ mol Table 5. Fitting constants for PCL : different decomposition curves and activation energy of each process 392 Intern.","label":"BIODEGRAD_POLY"}
{"id":6,"sentence":"Fig. 4. Changes in crystallinity and lateral crystal size [(110) \/ (200)] obtained from WAXD with molecular mass of PI midblock for solvent−cast PLA−b−PI−b−PLA triblock copolymers.","label":"POLY_STRUC"}
{"id":7,"sentence":"The viscosity−frequency curves of PLLA melts (Fig. 3) display a maximum instead of a horizontal plateau. This unusual behavior can be explained by the effect of a thermal degradation process, implying chain scission leading to a molar mass decrease,","label":"BIODEGRAD_PROP"}
{"id":8,"sentence":"This value is necessary in order to determine the weight−average molecular weight of a polymer by laser light scattering. Values of−0.0276 +−0.","label":"POLY_STRUC"}
{"id":9,"sentence":"Crystallinities were not calculated for samples aged for 30 days because they were too degraded to obtain clear thermographs ; the baseline drifted and the peaks were not well resolved.","label":"POLY_STRUC"}
{"id":10,"sentence":"The data of Mn versus time for 5 days of hydrolysis were fitted with the pseudo‐first‐order kinetics [cf. eq. (3)].","label":"POLY_STRUC"}
{"id":11,"sentence":"These equations relate filler content in the composite to the elongation and tensile strength of the composite, respectively. The Nielsen equation is as follows : ecomp 0 e0 [1−(ff) 1 \/ 3] (18)","label":"MECHANICAL_PROP"}
{"id":12,"sentence":"Figure 1 depicts the known routes to high−molecularweight PLA : condensation \/ coupling, azeotropic dehydrative condensation, or ring−opening polymerization of lac−tide.","label":"POLY_STRUC"}
{"id":13,"sentence":"Poly (lactic acid) can be crystallized by slow cooling, annealing it above the Tg, or strain crystallized [1]. Poly (lactic acid) can be a well−behaved thermoplastic with a reasonable shelf life for most single−use packaging applications and, when disposed of properly, will hydrolyze to harmless, natural products.","label":"BIODEGRAD_POLY"}
{"id":14,"sentence":"The physical and chemical properties of the polymer have a strong influence on enzymatic hydrolysis. PCL has a low melting point of 60 °C and a glass−transition temperature (Tg) of−60 °C.","label":"POLY_STRUC"}
{"id":15,"sentence":"and 80 °C at 100 % RH. 95 % confidence intervals are indicated with bars. The samples degraded at 80 °C exhibited a decrease in PDI to 1.5.","label":"BIODEGRAD_PROP"}
{"id":16,"sentence":"However, the difference between the composition of PEG in Week 1 (14. 0 %) and Week 20 (12. 3 %) was only 1.7 %, suggesting that degradation near the PEG segment was retarded.","label":"BIODEGRAD_POLY"}
{"id":17,"sentence":"(1) The simplest treatment of the above equation is to assume that the degradation can be adequately described by bimolecular kinetics. It is assumed that the concentration of water is considered constant during the hydrolysis process because the diffusion of water into the polymer is much faster than the reaction of water with the ester groups in the polymer chain.","label":"BIODEGRAD_PROP"}
{"id":18,"sentence":"Similarly, the Mn for PLA118 was reduced from 60, 700 Da to 1370 Da during the first 30 days of degradation and continued to degrade to 730 Da after 90 days.","label":"BIODEGRAD_PROP"}
{"id":19,"sentence":"Fig. 7. Rheological properties of blends with different amounts of compatibilizers : (A) complex viscosity ; (B) storage modulus ; (C) loss modulus ; (D) cole−cole plots.","label":"RHEOLOGICAL_PROP"}
{"id":20,"sentence":"The Young's modulus (Fig. 7a) and ultimate tensile strength values (Fig. 7c) are significantly enhanced when PLA end blocks form crystals, functioning as stronger cross−linking points in the elastomeric network (Fig. 5a), meanwhile, elongation at break shows some kind of slight drop due to crystallization of PLA end blocks.","label":"MECHANICAL_PROP"}
{"id":21,"sentence":"There was also little observable change for the samples degraded at 40 °C at 100 % RH (Fig. 3B). This is expected since the chain mobility below Tg is low.","label":"POLY_STRUC"}
{"id":22,"sentence":"DSC traces of the samples before and after conditioning are shown in Figures 11 and 12. The thermal properties of PBS, PBAT, and PBS \/ PBAT blends are summarized in Table 2.","label":"BIODEGRAD_POLY"}
{"id":23,"sentence":"Both of these values are in line with literature values for the hydrolysis of PLA which span from 20 to 24. 5 kcal mol−1 29−31.","label":"BIODEGRAD_PROP"}
{"id":24,"sentence":"the refractive index increments for poly (lactic acid) in these two solvents are too low to report. Bigg [100] also mentioned the effect of temperature on the degradation of PLA.","label":"BIODEGRAD_POLY"}
{"id":25,"sentence":"Table VI summarizes Runt ’ s data [97]. Kolstad [103] also performed isothermal crystallization kinetics studies of poly (L−lactide−co−meso−lactide), similar to the work of Runt.","label":"POLY_STRUC"}
{"id":26,"sentence":"In both, neutral and acidic media, hydrolysis showed an initial induction period over which no weight loss was observed, whereas the average molecular weight dropped drastically.","label":"BIODEGRAD_PROP"}
{"id":27,"sentence":"The kinetic parameters k0i and (E \/ R) i were calculated via the fitting of the data in a linear plot ; the subscript i represents each kinetic stage (1 or 2),","label":"BIODEGRAD_PROP"}
{"id":28,"sentence":"Chandra and Rustgi, 1998, L ö rcks, 1998, Lunt, 1998, Averous and Le Digabel, 2006) must have the intention of fast biodegradability.","label":"BIODEGRAD_PROP"}
{"id":29,"sentence":"the PLA crystals formed in the solvent−cast samples can obviously enhance the final mechanical property of these PLA−b−PI−b−PLA triblock copolymers as we will demonstrate in the next section.","label":"POLY_STRUC"}
{"id":30,"sentence":"To achieve that goal, changes in the total mass, percent crystallinity, melting temperature, and molecular weight of the fibers were monitored as a function of time.","label":"BIODEGRAD_PROP"}
{"id":31,"sentence":"For fibers aged under nitrogen purge conditions, a similar procedure was followed. For each fiber diameter, ∼30 mg samples of PLA fiber were placed into separate vials and purged with nitrogen before being capped.","label":"BIODEGRAD_POLY"}
{"id":32,"sentence":"The negative values are a result of benzene having a greater refractive index than poly (lactic acid). Because poly (lactic acid) has a similar refractive index to chloroform and tetrahydrofuran,","label":"BIODEGRAD_POLY"}
{"id":33,"sentence":"and mechanical property [17, 24, 25]. Tessie et al. reported the effect of crystallinity on mechanical property of PLA−based multiblock copolymers by annealing the selected samples.","label":"MECHANICAL_PROP"}
{"id":34,"sentence":"For PBAT, and the peak at 2959 cm−1 associated with the CH2 asymmetric stretching vibration [10, 11]. Table 2. FTIR absorption peaks of neat PLA, neat PBAT and PLA \/ PBAT blends.","label":"BIODEGRAD_POLY"}
{"id":35,"sentence":"The two−phase incompatibility of a resin blend often results in less favorable mechanical properties, manifested as brittle rupture, skin−core structures, and wire drawing [29], [30], [31].","label":"MECHANICAL_PROP"}
{"id":36,"sentence":"and (2) [32], where shear stress σ can be obtained from apparent viscosity and shear rate ; K is the apparent viscosity index ; n is the non−Newtonian index,","label":"RHEOLOGICAL_PROP"}
{"id":37,"sentence":"Biofragmentation is revealed by the identification of fragments of lower molecular weight (i. e. using chromatographic methods). Assimilation is estimated by the production of metabolites (e. g. respirometric methods)","label":"BIODEGRAD_PROP"}
{"id":38,"sentence":"As noted, the intensities of most of bands of the three crystal forms were increased by above 20 % when cooled to−100 °C. Normally,","label":"POLY_STRUC"}
{"id":39,"sentence":"The starch granules maintained their shape despite being subjected to heat and mechanical shear in the extruder. Thermal properties of the PLLA \/ starch composites were also reported.","label":"MECHANICAL_PROP"}
{"id":40,"sentence":"The addition of low MW PPG during processing introduced extra hydroxyl groups, further deteriorating the thermal stability of PLA. The transesterification reaction between PPG and PLA may result in the formation of monomers and oligomeric lactides. 3. 3.","label":"BIODEGRAD_POLY"}
{"id":41,"sentence":"13 The molecular weight of the PBS \/ PBAT blend was 1.70 times lower after being subjected to hydrolytic degradation. This is relatively high compared with PBS and PBAT.","label":"BIODEGRAD_POLY"}
{"id":42,"sentence":"After 30 days of degradation, there was not enough material remaining of either diameter to analyze. Statistically, there were no observable differences between the mass loss of the smaller PLA32 and larger PLA118 fibers under any given temperature or RH conditions.","label":"BIODEGRAD_PROP"}
{"id":43,"sentence":"which produced enzymes capable of changing the pH of the biodegradation system. The pH of the soil varied from 8 to 9. Rosa et al. [25] observed no changes in biodegradation rate when samples of PCL, PHB,","label":"BIODEGRAD_PROP"}
{"id":44,"sentence":"which is available at wileyonlinelibrary. com.] Figures 9 and 10 show the tensile and flexural modulus of the PP, PBS, PBAT, and PBS \/ PBAT as a function of conditioning time.","label":"BIODEGRAD_POLY"}
{"id":45,"sentence":"In comparison to random copolymers which usually had a random assembly of monomers in their chain segments showed only one Tm and broad melting peak (Figure 6D).","label":"POLY_STRUC"}
{"id":46,"sentence":"(14) This dependence model was first deduced from the correlation that was found between the difference in the temperature at which the degradation takes place with Pseudomonas sp. lipase and the melting point of the polyester.","label":"BIODEGRAD_PROP"}
{"id":47,"sentence":"Surprisingly, the aPLA after 3 days in distilled water at 70 °C exhibited a clear dual‐melting peak (117 and 128 °C).","label":"BIODEGRAD_POLY"}
{"id":48,"sentence":"This study opens the way for the future design of tailored enzymes able to hydrolyze a broad range of polyesters. The overall volume of the pockets is 343.","label":"BIODEGRAD_PROP"}
{"id":49,"sentence":"As the distance between the bonded couple is comparable among the three crystal forms, MDDI with α−neighboring protons would not depend on the crystalline structure,","label":"POLY_STRUC"}
{"id":50,"sentence":"They had used the following equation to calculate the surface energy at the fold surface : where Vasanthakumari and Pennings [84] also performed crystallization kinetics studies on poly (L−lactic acid).","label":"POLY_STRUC"}
{"id":51,"sentence":"Glycidyl methacrylate (GMA) was chosen as the reactive agent to achieve interfacial cross−copolymerization between PLA and PCL phases. Morphological, rheological, and mechanical properties and biodegradabilities of blends were investigated.","label":"BIODEGRAD_POLY"}
{"id":52,"sentence":"Effects of Temperature on Degradation Rates The hydrolysis rate constants calculated for PLA shown in Table 1 can be fit with the Arrhenius equation to obtain the activation energy for the hydrolysis of PLA.","label":"BIODEGRAD_PROP"}
{"id":53,"sentence":"05 Oester — Ca — Cb 109. 5 Cb — Hb 1.05 Ca — Cb — Hb 109. 5 Poly (lactid acid) is a slower−crystallizing material, similar to poly (ethylene terephthalate).","label":"BIODEGRAD_POLY"}
{"id":54,"sentence":"L)−PLA 63 178 95 \/ 5 (L \/ D, L)−PLA 59 164 90 \/ 10 (L \/ D, L)−PLA 56 150 85 \/ 15 (L \/ D,","label":"BIODEGRAD_POLY"}
{"id":55,"sentence":"49 above the glass transition temperature, storage modulus is dependent to the degree of crystallinity. Below glass transition temperature, the modulus of crystalline as well as amorphous phase is almost identical.","label":"POLY_STRUC"}
{"id":56,"sentence":"This result agrees with the observed mechanical properties of the conditioned samples as studied. Table 3. Relative Molecular Weight (M1 \/ M2) of the PBS, PBAT,","label":"BIODEGRAD_POLY"}
{"id":57,"sentence":"The modulus of PLAF was close to that of PP, but statistically significantly lowers. Statistical analysis indicated that temperature significantly affects elastic modulus of the samples.","label":"MECHANICAL_PROP"}
{"id":58,"sentence":"the first kinetic stage for both aPLA and cPLA fit the VFT equation (R2 ∼1). For the second kinetic phase, aPLA fit better than cPLA.","label":"BIODEGRAD_POLY"}
{"id":59,"sentence":"or itaconic acid, leading to a carboxyl functional polymer [19 – 21]. The PLA can also be postreacted with acid anhydrides such as maleic or succinic to convert the hydroxyl to a carboxylic end−group [21].","label":"BIODEGRAD_POLY"}
{"id":60,"sentence":"The Fig. 4 presents the typical thermogram of PLA40 showing the Tg values at−33. 7. C and 56. C, for PBAT and PLA phases, respectively ;","label":"BIODEGRAD_POLY"}
{"id":61,"sentence":"the isomer ratio, and the temperature of hydrolysis [1]. In order for PLA to be processed on large−scale production lines in applications such as injection molding, blow molding, thermoforming,","label":"BIODEGRAD_PROP"}
{"id":62,"sentence":"A complete polyester biodegradation would be the result of a microbial synergy. When the scission reactions by specific enzymes are difficult (i. e. crystalline area, hydrophobic zones and steric hindrances), other enzymes are implicated in the transformation of the molecular edifices.","label":"BIODEGRAD_PROP"}
{"id":63,"sentence":"Abstract The role of temperature, shear and oxygen on PLA degradation was investigated. Thermo−mechanical degradation induces a larger decrease in PLA molecular weight than thermo−oxidative degradation.","label":"BIODEGRAD_PROP"}
{"id":64,"sentence":"Fitting parameters for the proposed three degradation mechanisms for PCL are shown in Table 5. The results show that the activation energies of the processes s1 and s2 are positives, being Ea2 > Ea1.","label":"BIODEGRAD_PROP"}
{"id":65,"sentence":"Scanning electron microscopy (SEM) images of the PLA \/ PPG composites : (a) PLA, (b) PLA \/ PPG−200, (c) PLA \/ PPG−400, (d) PLA \/ PPG−600, (e) PLA \/ PPG−800, (f) PLA \/ PPG−1000.4.","label":"BIODEGRAD_POLY"}
{"id":66,"sentence":"Characteristics of polylactides and poly (e−caprolactone), RS : residual solvent ; RM : residualmMonomer ; : rotatory power in CHCL3 at 30 °C (polarimetric) ; [g] : intrinsic viscosity ;","label":"BIODEGRAD_POLY"}
{"id":67,"sentence":"Park et al. [123] had investigated the morphology of the PLLA−and the star−PLA \/ cornstarch composites using microscopy. Spherulites of PLLA and star−PLA were grown radially at 110 °C and analyzed by optical microscopy.","label":"BIODEGRAD_POLY"}
{"id":68,"sentence":"In block copolymers P3HP−b−P4HB, all corresponding carbons in 13C NMR spectrum clearly showed single and sharp resonance peaks with one small satellite peak in each composition (Figure 3A),","label":"POLY_STRUC"}
{"id":69,"sentence":"These differences led to a reduction of the Tm in their work similar to the reduction observed in this study. Molecular Weight Changes The ester linkages of PLA can be easily hydrolyzed leading to chain scission and an observed change in the molecular weight of the remaining material.","label":"BIODEGRAD_PROP"}
{"id":70,"sentence":"However, PLLA showed rapid degradation at 240 °C, a temperature that has been considered for extrusion (Taubner and Shishoo, 2001), with a 5. 80 % weight loss after two hours of test.","label":"BIODEGRAD_PROP"}
{"id":71,"sentence":"The hydrolytic degradation of poly (lactic acid) (PLA) devices has previously been reported as size dependent for devices such as plates, microspheres, and films between 2 and 0.3 mm in thickness or diameter.","label":"POLY_STRUC"}
{"id":72,"sentence":"However, crystalline structures and highly organised molecular networks (Muller et al., 1998) are not favourable to the enzymatic attack, since the access to the internal part of these structures is extremely constrictive.","label":"POLY_STRUC"}
{"id":73,"sentence":"0 to−53. 7 °C) is more significant than the decrease in Tg2 of PLA end blocks (from 74. 8 to 70.6 °C) when PI midblock length increases.","label":"BIODEGRAD_POLY"}
{"id":74,"sentence":"and C−O−C stretching at 1181, 1084, and 1043 cm−1 [27]. On the contrary, the spectrum of pure PCL (Figure 2 (b)) showed absorption bands corresponding to C 0 O stretching vibration at 1723 cm−1,","label":"BIODEGRAD_POLY"}
{"id":75,"sentence":"Figure 9. TGA thermograms of the neat PLA and PLA \/ PPG composites. 3. 4. Micro−Morphology Figure 10 shows the micro−morphology images of the neat PLA and PLA \/ PPG composites.","label":"BIODEGRAD_POLY"}
{"id":76,"sentence":"Again, a vacuum desiccator was used to store these films. This makes this enzyme a good starting point for further rational engineering efforts to improve polymer binding while keeping high thermostability.","label":"MECHANICAL_PROP"}
{"id":77,"sentence":"This study was primarily aimed to investigate the tensile properties of PLA \/ PBAT blends and PLA fiber−reinforced PBAT composite at room temperature and frozen temperature.","label":"MECHANICAL_PROP"}
{"id":78,"sentence":"Distannoxane complexes have also shown high efficiencies in copolymerization of various lactones and lactide [68]. The polymerization of lactide with a tin−substituted mesoporous silica molecular sieve gave polymers of higher molecular weights, higher conversions,","label":"POLY_STRUC"}
{"id":79,"sentence":"17 m 240 3. 41 3. 40 m 221 4. 02 4. 02 s The enthalpy of melting DHm) for a pure crystal (100 % crystallinity) was calculated through extrapolation to be 93.","label":"POLY_STRUC"}
{"id":80,"sentence":"Mn was still very high at 85 % of its original value. At that point, the weight loss reached approximately 75 %, and Mn decreased to approximately 11 % of its original value.","label":"BIODEGRAD_PROP"}
{"id":81,"sentence":"In contrast to the usual belief that the kinetics of crystallization and those of hydrolytic degradation were closely coupled, these observations showed that for crystallizable PLA, the initial crystalline state of the sample did not play an important role.","label":"POLY_STRUC"}
{"id":82,"sentence":"The in‐vitro hydrolytic behavior of diblock copolymer films consisting of poly (ε‐caprolactone) (PCL)","label":"BIODEGRAD_POLY"}
{"id":83,"sentence":"and thermoforming. Polylactide melts are shear thinning, similar to polystyrene. The melt viscosities of high−molecular−weight PLA are 5, 000 to 10, 000 poise (500 – 1000 Pa−s)","label":"BIODEGRAD_POLY"}
{"id":84,"sentence":"(6, 7) On the other hand, random copolymers of scl and mcl monomers are very useful as they combine the strength of scl monomers and elasticity of the mcl monomers.","label":"POLY_STRUC"}
{"id":85,"sentence":"9 J \/ m) was similar despite a higher content of soft PCL, which was probably due to the greater particle size of PCL than that of the uncompatibilized PLA \/ PCL (90 \/ 10) blend.","label":"BIODEGRAD_POLY"}
{"id":86,"sentence":"Inside cells, transported molecules are oxidised through catabolic pathways conducing to the production of adenosine triphosphate (ATP) and constitutive elements of cells structure. Aerobic respiration : numerous microorganisms are able to use oxygen as the final electron acceptor.","label":"BIODEGRAD_PROP"}
{"id":87,"sentence":"Transmission infrared spectra for P3HP samples were accumulated on an AIM−8800 automatic infrared microscope (Shimadzu Co., Kyoto, Japan) or an IMV−4000 automatic infrared microscope (JASCO Co.,","label":"BIODEGRAD_POLY"}
{"id":88,"sentence":"140 Sun [134] indicated that the starch granules were incompatible with the PLLA matrix, based on SEM micrographs. Some gaps existed between the starch granules and PLLA at all weight ratios.","label":"BIODEGRAD_POLY"}
{"id":89,"sentence":"A plot of melt flow rate versus molecular weight is shown. Nuclear magnetic resonance (NMR) data of PLA is presented in the literature [4, 31].","label":"POLY_STRUC"}
{"id":90,"sentence":"Kijchavengkul et al. (2008) have found crosslinking reactions that are responsible of the brittleness of PBAT (poly [butylene adipate terephtalate]). Thermal degradation of thermoplastic polymers occurs at the melting temperature when the polymer is transformed from solid to liquid (e. g. 159 – 178 °C for l−PLA depending on its molecular weight, 137 – 169 °C for P (HB \/ HV) (poly [hydroxybutyrate−co−hydroxyvalerate]) depending on the percentage of hydroxyvalerate, 175 °C for PHB (poly [hydroxybutyrate]) (Ojumu et al., 2004).","label":"BIODEGRAD_POLY"}
{"id":91,"sentence":"The working temperature is dependent on the melt viscosity, which is, in turn, dependent on the weight−average molecular weight of PLA, the amount of plasticizer,","label":"RHEOLOGICAL_PROP"}
{"id":92,"sentence":"the responses of each carbon in the blend of P3HP and P4HB produced single and sharp peaks because there was no interaction between 3HP monomer and 4HB monomer (Figure 3C).","label":"BIODEGRAD_POLY"}
{"id":93,"sentence":"The fact that this peak is seen only after 7 weeks indicates that the rate of degradation is slow. Peak values for degradation at pH 9. 5 were similar to those observed for pH 7. 4 (both film and water soluble products), indicating the presence of ester bonds and carboxylic acid products.","label":"BIODEGRAD_PROP"}
{"id":94,"sentence":"The fastest rates of crystallization for pure PLA are found in the temperature range of 110 – 130 °C, which yields spherulitic crystalline morphology [95, 98, 101 – 106].","label":"POLY_STRUC"}
{"id":95,"sentence":"Elongation of PLA \/ PBAT blends rapidly decreased upon the addition of PLA to the blends. The decrease of temperature from room temperature to−18. C allowed elastic modulus and the ultimate tensile strength of PLA \/ PBAT blends and composite, neat PLA,","label":"MECHANICAL_PROP"}
{"id":96,"sentence":"The results for elastic modulus (E), ultimate tensile strength (UTS), and elongation at break (Eb) are shown in Figs. 1−3, respectively. 3. 1.1 Elastic modulus From Fig. 1, it could be clearly observed that the neat PLA exhibited much higher elastic modulus (around 567−974 MPa) than that of the neat PBAT (around 40−50 MPa),","label":"MECHANICAL_PROP"}
{"id":97,"sentence":"Degradation at higher pH is expected to be accelerated because of the presence of a higher concentration of hydroxyl ions (OH −) which can cleave the ester bonds in the PCL chains.","label":"BIODEGRAD_PROP"}
{"id":98,"sentence":"In addition, we also observed CH2 and C−C (crystal phase) of PCL at 2864 cm−1 and 1293 cm−1 of PCL.","label":"BIODEGRAD_POLY"}
{"id":99,"sentence":"the quenched cPLA was compared with the annealed cPLA. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary. com.]","label":"BIODEGRAD_POLY"}
{"id":100,"sentence":"Furthermore, the spherulite morphology of the 30 days exposed PBS and PBS \/ PBAT exhibits clear ring‐banded spherulites, which can be attributed to their reduced molecular weight.","label":"BIODEGRAD_POLY"}
{"id":101,"sentence":"Krzan et al., 2006, ISO 14855, 1485 Krzan et al., 2006). Actually, the measure of the weight loss of samples even from buried materials is not really representative of a material biodegradability, since this loss of weight can be due to the vanishing of volatile and soluble impurities.","label":"BIODEGRAD_PROP"}
{"id":102,"sentence":"Furthermore, the impact strength of PBAT remains unaffected up to 30 days of exposure. However, it was clearly observed that the fracture mode of PBS \/ PBAT changed from ductile to brittle after being exposed to high heat and humid conditions.","label":"BIODEGRAD_POLY"}
{"id":103,"sentence":"at room temperature and−18. C were investigated. The concentrations of PLA in the blends were 10 %, 20 %, 30 % and 40 % (by volume).","label":"POLY_STRUC"}
{"id":104,"sentence":"The reduction in MW of the neat PLA is probably due to the random chain scission at the ester groups affected by both processing temperature and a trace amount of water in PLA.","label":"BIODEGRAD_PROP"}
{"id":105,"sentence":"One of those is even active on PET with ≈ 15 % crystallinity. (16) For a polymer to be hydrolyzed, the polymeric chains need to have enough mobility to reach the enzyme−active site.","label":"POLY_STRUC"}
{"id":106,"sentence":"These results confirm the low thermal stability of PLLA, lower than that of PCL which is close to that of PET, and also the existence of a narrower temperature window for processing of PLLA without thermal degradation. 3. 3 Rheology Rheology and thermogravimetry provide complementary results for the analysis of polymer thermal degradation and stability but the former is considered more sensitive because it can detect both low conversion ratios for chain scission and crosslinking.","label":"BIODEGRAD_POLY"}
{"id":107,"sentence":"An intramolecular random protonation of carbon of the ester group conduces also to the hydrolysis of ester linkages. This hydrolysis gives different fragments of lower molecular weights.","label":"BIODEGRAD_PROP"}
{"id":108,"sentence":"or biomass, predominantly due to the enzymatic actions of microorganisms ” [20]. Figures 10 and 11 show the results of our biodegradability studies on pure PLA and PCL and compatibilized PLA \/ PCL (90 \/ 10)","label":"BIODEGRAD_POLY"}
{"id":109,"sentence":"and the working equation is obtained as 24 : (4) where and. The advantage of this model over the more simplistic first order rate equation is that it incorporates the autocatalytic behavior observed for PLA degradation.","label":"BIODEGRAD_PROP"}
{"id":110,"sentence":"Therefore, an attempt has been made to introduce aliphatic moieties into aromatic polyesters in order to enhance the hydrolytic degradation. 9 For example, poly (butylene adipate‐co‐terephthalate) (PBAT) is a commercialized biodegradable aliphatic – aromatic copolyester.","label":"BIODEGRAD_PROP"}
{"id":111,"sentence":"The curves of the logarithm of the storage modules (G′) and loss modulus (G′′) versus the logarithm of the sweep frequency for PLA \/ PBAT blends with different amounts of compatibilizers are shown in Fig. 7 (B)","label":"RHEOLOGICAL_PROP"}
{"id":112,"sentence":"Wiles and Scott, 2006). This strategy is used by polyolefin manufacturers to enhance degradability of plastic bags, packaging, agricultural films, etc. (Weiland et al., 1995,","label":"BIODEGRAD_PROP"}
{"id":113,"sentence":"which is available at wileyonlinelibrary. com.] Hydrolytic Degradation Mechanism of PBS and PBAT It is known that the ester linkages of PBS and PBAT are more sensitive to elevated temperature and moisture. 17, 19 Therefore, in the presence of moisture,","label":"BIODEGRAD_POLY"}
{"id":114,"sentence":"Pellets were held in a vacuum oven at 60 °C for PLLA and at 30 °C for PCL for at least 24 h prior to measurements. 2.","label":"BIODEGRAD_POLY"}
{"id":115,"sentence":"Surprisingly, even the so‐called amorphous grade PLA developed a crystalline structure when it was placed in aqueous media. This probably contributed to the levelling out of the differences in terms of the degradation rate between the amorphous and semicrystalline grades.","label":"POLY_STRUC"}
{"id":116,"sentence":"Poly (lactic acid) exists as a polymeric helix, with an orthorhombic unit cell. The tensile properties of PLA can vary widely, depending on whether or not it is annealed or oriented or what its degree of crystallinity is.","label":"BIODEGRAD_POLY"}
{"id":117,"sentence":"The tan δ peak temperature is referred to as Tg, and two distinct Tg transitions at 73. 94 °C and−23. 9 °C are attributed to PLA and PBAT, indicating the immiscibility of the two components [33].","label":"POLY_STRUC"}
{"id":118,"sentence":"(3) The advantage of this model is that it can be used to simplistically calculate the decrease in molecular weight of the polymer. However, it has been shown that the newly formed carboxylic acid end groups accelerate the degradation process 23, so the major disadvantage of the above model is that it does not take into account the autocatalytic behavior of the degradation.","label":"BIODEGRAD_PROP"}
{"id":119,"sentence":"Fig. 3. WAXD curves for (a) melt−quenched and (b) solvent−cast PLA−b−PI−b−PLA triblock copolymers.","label":"BIODEGRAD_POLY"}
{"id":120,"sentence":"and tensile deformation test, respectively. The PLA crystallization of the end blocks and its influence on enhancement of mechanical property of the triblock copolymers will be revealed in this work.","label":"MECHANICAL_PROP"}
{"id":121,"sentence":"This indicates that though the mechanical properties of the blend exhibit the anti−synergism, the thermal degradation of the polymer blend shows no interaction (Aoyagi et al., 2002 ;","label":"MECHANICAL_PROP"}
{"id":122,"sentence":"Figure 6 Open in figure viewer PowerPoint Fits for both the non‐autocatalytic (Eq. 3) and the autocatalytic (Eq. 4) degradation models as applied to the PLA32 and PLA118 fibers degraded at 40, 60,","label":"BIODEGRAD_PROP"}
{"id":123,"sentence":"9 CONCLUSIONS The hydrolysis of PLA in aqueous media was investigated by the monitoring of changes in the sample weight, water uptake, molecular weight distribution, melting enthalpy,","label":"BIODEGRAD_PROP"}
{"id":124,"sentence":"In this case, the initial hydrolysis was facilitated by high temperature and later by the presence of thermophylic microorganisms. A temperature of 46 °C facilitated the biodegradation by microorganisms that used the polymers as nutrients.","label":"BIODEGRAD_PROP"}
{"id":125,"sentence":"(28) Metabolic engineering and synthetic biology approaches developed the microbial production of various PHA random copolymers as well as homopolymers and block copolymers. (28, 29)","label":"POLY_STRUC"}
{"id":126,"sentence":"the number and size of isolated PBAT particles decrease more markedly in samples with long−chain compatibilizers. These long chains achieve enhanced interpenetration of the relevant homopolymers,","label":"POLY_STRUC"}
{"id":127,"sentence":"When starch was added, the glass−transition temperatures of both L−PLA and star−PLA \/ cornstarch Table XXII. Mechanical Properties of Composites Containing Cornstarch (CS)","label":"BIODEGRAD_POLY"}
{"id":128,"sentence":"Fig. 7 further shows the variations of the Young's modulus, elongation at break, and ultimate tensile strength with increasing PI midblock molecular mass for these triblock copolymers.","label":"MECHANICAL_PROP"}
{"id":129,"sentence":"The effect of temperature on the mechanical properties of PHB and PHB−V was also evident as demonstrated previously [2]. Fig. 3. Biodegradation of PHB based on mass retention.","label":"BIODEGRAD_PROP"}
{"id":130,"sentence":"0 and (b) vermiculite for 0, 7, 15, 25, and 45 days at 58 °C. Fig. 5. Logarithmic reduction of molecular number (Mn) in of PBAT films from hydrolysis in phosphate buffer solution (pH 0 8. 0)","label":"BIODEGRAD_PROP"}
{"id":131,"sentence":"Two linear portions were found ; these corresponded to the following relationships : (7) where is the molecular weight before hydrolysis, is the number‐average molecular weight intercept of the second hydrolysis stage, k1 and k2 are the kinetic constants for each stage,","label":"POLY_STRUC"}
{"id":132,"sentence":"59 PLLA \/ HACS 60 \/ 40 45. 4 2. 0 3. 2 0.45 Table XXIII. Mechanical Properties of Starch – PLA Composites Containing Selected Plasticizers Tensile strength Elongation at break Modulus Blend (MPa) (%) (GPa)","label":"MECHANICAL_PROP"}
{"id":133,"sentence":"When a certain viscous polymer melt is in a closed mixer and is in an isothermal steady−state flow, the mechanical energy dissipation can be calculated by Equation (4) [33].","label":"RHEOLOGICAL_PROP"}
{"id":134,"sentence":"7 joules \/ gram, with practical DHm in the 40 – 50 joules \/ gram range, yielding polymers with 37 – 47 % crystallinity [94 – 96].","label":"POLY_STRUC"}
{"id":135,"sentence":"In conclusion, tri−block copolymers were determined to be ideal compatibilizers for PLA \/ PBAT blends. Enzymes, particularly esterases, play an important role in the biodegradation of polyesters.","label":"POLY_STRUC"}
{"id":136,"sentence":"which chain packing is completely unknown before, contain at least two chains in one unit cell. Interestingly, the splittings of the CH2 vibration bands of the γ−form,","label":"POLY_STRUC"}
{"id":137,"sentence":"This is because when the PEG segments are removed and its composition fell, it will provide less hindrance to the PCL chains and enable them to arrange themselves suitably, thus attaining higher crystallinity.","label":"BIODEGRAD_POLY"}
{"id":138,"sentence":"the long chains of the tri−block copolymers deeply interpenetrated the homopolymers and increased the entanglement density. In addition, the η ∗ of the blends with HPB compatibilizers was higher than the blends with LPB compatibilizers.","label":"POLY_STRUC"}
{"id":139,"sentence":"Among the biodegradable polymers, poly (butylene succinate) (PBS) is a promising aliphatic polyester, made from fossil fuel based 1, 4‐butanediol and succinic acid precursors,","label":"BIODEGRAD_POLY"}
{"id":140,"sentence":"and 80 °C under nitrogen purge and 100 % RH from 1 to 90 days is shown in Fig. 1.Figure 1 Open in figure viewer PowerPoint Weight loss (%) data during the degradation of PLA fiber at 40, 60,","label":"BIODEGRAD_PROP"}
{"id":141,"sentence":"Thus, there is a critical need to understand the effect of microbial population, family of microorganisms, and their enzymatic specificity in different microbial environments on the total biodegradation of biodegradable polyesters and their biodegradation rates.","label":"BIODEGRAD_PROP"}
{"id":142,"sentence":"In addition, the upfield shoulder of the carbonyl carbon was also attributed to the amorphous phase. As noted, the β−form and γ−form crystals show very similar α CH2 and β CH2 carbon resonances,","label":"POLY_STRUC"}
{"id":143,"sentence":"and (4). Therefore, when the rotor speed N is constant, the shear rate γ of the material is a certain value, so the non−Newtonian index n of the material is also a certain value.","label":"RHEOLOGICAL_PROP"}
{"id":144,"sentence":"However, most plastics need hundreds of years to be completely degraded in nature. Such serious environmental pollutions brought by non−degradable plastics ultimately endanger our health once released into nature and thus should never be neglected [2, 3, 4, 5].","label":"BIODEGRAD_PROP"}
{"id":145,"sentence":"Previous studies have noted that with the increase of PEG composition, the degradability of the copolymer is enhanced. 11, 17 The other reason is that the degradation of the polymer is still at the induction stage as analyzed in the later section.","label":"BIODEGRAD_PROP"}
{"id":146,"sentence":"The lower biodegradability and longer initial time lag of pure PLA might be problematic when PLA is composted with easy compostable waste under industrial composting conditions [20, 33].","label":"BIODEGRAD_PROP"}
{"id":147,"sentence":"The simplest hydrolysis kinetics model assumes that the ester‐bond breakup rate is proportional to time. Because the number of polymer chains is equal to the number of carboxylic end groups,","label":"BIODEGRAD_PROP"}
{"id":148,"sentence":"The plots of torque and temperature versus time for the PLA \/ PPG composites mixed for 20 minutes in the torque rheometer are showed in Figure 3. From Figure 2,","label":"BIODEGRAD_POLY"}
{"id":149,"sentence":"(10−13) Manipulation of natural PHA production machinery and synthesis genes from different sources has led to the production of innumerable number of PHA polymers.","label":"BIODEGRAD_POLY"}
{"id":150,"sentence":"This may be due to the PBAT having sufficient molecular weight to form a significant degree of entanglement up to 30 days of hydrolysis environments. 14, 31 Furthermore,","label":"BIODEGRAD_POLY"}
{"id":151,"sentence":"the mean value over the selected time interval, may be taken as a measure of the rate of degradation ; Rz is the percentage variation of the adjusted torque per unit processing time,","label":"BIODEGRAD_PROP"}
{"id":152,"sentence":"However, the addition of PLA to PLA \/ PBAT blends from 10 % to 40 % did not affect the ultimate tensile strength. For the same concentration of PLA (40 %) in PLA−PBAT mixture, PLA (fiber) \/ PBAT composite exhibited the higher elastic modulus and ultimate tensile strength that that of PLA \/ PBAT blends.","label":"BIODEGRAD_POLY"}
{"id":153,"sentence":"Preparation of PLA \/ PCL \/ GMA Mixtures The blend ratios of PLA to PCL of 90 \/ 10 and 70 \/ 30 (weight percent) were used in the study,","label":"BIODEGRAD_POLY"}
{"id":154,"sentence":"Fig. 7. Changes in (a) the Young's modulus, (b) elongation at break and (c) ultimate tensile strength with increasing PI midblock molecular mass for solvent−cast and melt−quenched PLA−b−PI−b−PLA triblock copolymers.","label":"MECHANICAL_PROP"}
{"id":155,"sentence":"Meanwhile, Costa et al. proved that melt viscosity was very sensitive to slight changes in MW, whereas the torque of the polymer depends on its melt viscosity [26].","label":"RHEOLOGICAL_PROP"}
{"id":156,"sentence":"The isothermal experiments were carried out at the same conditions as the rheometric studies, for two hours at the selected temperatures. 2. 4 Rheometry The dynamic flow properties of the molten materials were measured with a Rheometrics ARES using parallel plate geometry (plate diameter : 25 mm, gap : 1 mm).","label":"RHEOLOGICAL_PROP"}
{"id":157,"sentence":"The amorphous PLA had a D−to L−lactide ratio of 18 to 82, and the semicrystalline PLA had a D−to L−lactide ratio of 5 to 95 [120].","label":"BIODEGRAD_POLY"}
{"id":158,"sentence":"8 are quite similar to those in Fig. 7. At first, the results demonstrate that crystallization of PLA end blocks can obviously enhance the yield stress and strain−hardening modulus (Figs. 8a and c), apparently through the stronger anchoring effect of PLA lamellar crystals in the network (Fig. 5a), while the yield strain (Fig. 8b) only shows a slight drop with the PLA crystals formed in the system.","label":"POLY_STRUC"}
{"id":159,"sentence":"Fig. 8. Changes in (a) yield stress, σ eng, (b) yield strain, ε eng, and strain−hardening modulus,","label":"MECHANICAL_PROP"}
{"id":160,"sentence":"(38) Following gentle addition of ethanol to the solvent of putative block copolymer P3HP−b−P4HB, only one fraction was precipitated. The microstructure of this fraction was analyzed by NMR.","label":"POLY_STRUC"}
{"id":161,"sentence":"33 Figure 2 Open in figure viewer PowerPoint Hydrolysis reaction of PBS. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary. com.]","label":"BIODEGRAD_PROP"}
{"id":162,"sentence":"In this work, we blended PCL and PLA and compatibilized mixtures by exposing them to electron−beam irradiation (20 kGy) in the presence of glycidyl methacrylate (GMA) with the aim of reducing brittleness and increasing thermal stability, melt viscosity,","label":"BIODEGRAD_POLY"}
{"id":163,"sentence":"This is due to the impermeability of the crystalline region [9, 83]. Fig. 6. Aluminum alkoxide polymerization mechanism [76]. Pure poly (D−Lactide) or poly (L−Lactide) has an equilibrium crystalline melting point of 207 °C [56, 57, 84, 85] but typical melting points are in the 170 °C – 180 °C range.","label":"POLY_STRUC"}
{"id":164,"sentence":"and amorphous PLA hard domains with Tg, PLA are shown in (b). (For interpretation of the references to color in this figure legend,","label":"BIODEGRAD_POLY"}
{"id":165,"sentence":"which was much larger than 1.This provided additional clear evidence that the samples were block copolymer of P3HP−b−P4HB. For a random copolymer of P (3HP−co−4HB), F3HP * 3HP 0 0.2893, F4HB * 4HB 0 0.1074, F4HB * 3HP 0 0.3455,","label":"POLY_STRUC"}
{"id":166,"sentence":"both PLA32 and PLA118 samples showed an average crystallinity of 35 %. During the first 24 h of aging at 60 °C and 100 % RH,","label":"BIODEGRAD_POLY"}
{"id":167,"sentence":"TPEs are always desirable for various applications, including automotive, electrical, chemical and biomedical fields [[5], [6], [7]].","label":"POLY_STRUC"}
{"id":168,"sentence":"(b) The measure of the weight loss is frequently used for the estimation of biodegradability. This method is standardised for in situ biodegradability tests (NF EN ISO 13432, 1343, ISO 14852, 1485,","label":"BIODEGRAD_PROP"}
{"id":169,"sentence":"Tensile testing was performed at room temperature with a gauge speed of 10 mm \/ min and a gauge length of 25 mm. The tensile and impact strengths mentioned are the mean values of four independent tests.","label":"MECHANICAL_PROP"}
{"id":170,"sentence":"and increases the interfacial adhesion. Compared to the short−chain tri−block copolymers, the long−chain tri−block copolymers were able to more effectively reduce the interfacial tension and toughen the immiscible PLA \/ PBAT blends, thus improving the elongation at break of the PLA \/ PBAT blends to a greater extent.","label":"POLY_STRUC"}
{"id":171,"sentence":"and PHB−V were aged thermally prior to testing for biodegradation. An elevated temperature favored the biodegradation of all of the polymers studied, as shown by the smaller mass retention in soil compost at 46 °C compared to 24 °C.","label":"BIODEGRAD_PROP"}
{"id":172,"sentence":"The crystallinity values were obtained by using the following heat of fusion values for 100 % crystalline materials : Δ H0 PCL 0 136, 100 J \/ kg,","label":"POLY_STRUC"}
{"id":173,"sentence":"and 80 °C in terms of the weight loss and Mn evolution. They reported faster degradation in commercial PLA, which comprised a small amount of d‐lactate (by opposition to the major l‐lactate constituent) in their composition.","label":"BIODEGRAD_PROP"}
{"id":174,"sentence":"and melt temperatures, respectively. In contrast to Park et al. [123], the crystallization temperatures of the composites were not affected by the starch contents.","label":"POLY_STRUC"}
{"id":175,"sentence":"Figure 4 Open in figure viewer PowerPoint SEM micrographs of the cPLA sample surfaces before and after hydrolysis at 70 °C : (a) before hydrolysis, (b) after 1 day in an alkaline medium, (c) after 5 days in an alkaline medium,","label":"BIODEGRAD_PROP"}
{"id":176,"sentence":"and 80 °C, to determine the kinetic constants. Figure 7 Open in figure viewer PowerPoint Arrhenius plots for rate constants obtained with Eq. 3 (A)","label":"BIODEGRAD_PROP"}
{"id":177,"sentence":"and 80 °C and 100 % RH. The rate constants for both PLA32 and PLA118 samples, calculated with both models, increased by roughly one order of magnitude for each 20 °C temperature increase.","label":"BIODEGRAD_POLY"}
{"id":178,"sentence":"and (70 \/ 30) (■) blends. Figure 11 Rate of biodegradation of cellulose (x), pure PLA (▲), pure PCL (△),","label":"BIODEGRAD_POLY"}
{"id":179,"sentence":"This stereo−chemical makeup is very easily controlled by the polymerization with D−lactide, L−lactide, D, L−lactide, or meso−lactide, to form random or block stereocopolymers, while the molecular weight is directly controlled by the addition of hydroxylic compounds (i. e., lactic acid, water, alcohols) [1].","label":"POLY_STRUC"}
{"id":180,"sentence":"Since the main production processes of PLA are based on melt processing, especially extrusion and injection moulding which require high temperature and shear, it is crucial to understand the structural, thermal and rheological changes that can occur during these processes [11].","label":"BIODEGRAD_PROP"}
{"id":181,"sentence":"and 1.49 ppm (k,−CH (CH3) -). The weight contents of the BT, BA, and LA parts were calculated by integrating the ratio of the peaks at 8. 11, 2. 34,","label":"POLY_STRUC"}
{"id":182,"sentence":"Both the β−and γ−form P3HPs were found to adopt the all−trans conformation, (5a, 5b) which accord well with the X−ray results.","label":"POLY_STRUC"}
{"id":183,"sentence":"which dissolves PLA but not PCL [6, 23]. The precipitate so obtained was vacuum dried at 50 °C for 24 hours. 2. 5.","label":"BIODEGRAD_POLY"}
{"id":184,"sentence":"It has been reported that the PP is resistant to moisture absorption even at elevated temperatures. 28 On the contrary, moisture absorption of PBS, PBAT,","label":"BIODEGRAD_POLY"}
{"id":185,"sentence":"These enzymes are usually only active on aliphatic polyesters, but a few have showed catalytic activity for semi−aromatic polyesters. Because of the importance of these processes, an atomic−level characterization of how common polyesters are degraded by esterases is necessary.","label":"POLY_STRUC"}
{"id":186,"sentence":"The relationship between the torque Z, the rotor rotational speed N, the non−Newtonian index n, and the temperature T can be obtained from Equations (3)","label":"RHEOLOGICAL_PROP"}
{"id":187,"sentence":"and 31.00 kJ \/ mol, respectively), which indicates that PBAT can cocrystallize [32]. In the case of PBAT, the soft aliphatic BA unit is infused into the BT crystal lattice [30].","label":"BIODEGRAD_POLY"}
{"id":188,"sentence":"With considering the intermolecular origination of these splitting bands, their out phase changing with the backbone stretching, in fact, likely indicates that during melting, the γ−form are first transformed to some mesophase,","label":"POLY_STRUC"}
{"id":189,"sentence":"In this study, the durability of poly (butylene succinate) (PBS), poly (butylene adipate‐co‐terephthalate) (PBAT),","label":"BIODEGRAD_POLY"}
{"id":190,"sentence":"The tensile strength of samples with different amounts of compatibilizers decreased slightly but remained above 52 MPa. The addition of tri−block compatibilizers in our work greatly improved the toughness properties and retained the tensile strength of PLA \/ PBAT blends.","label":"MECHANICAL_PROP"}
{"id":191,"sentence":"the tensile deformation tests on PLA−b−PI−b−PLA triblock copolymers were performed at 23 °C by using a universal testing machine,","label":"MECHANICAL_PROP"}
{"id":192,"sentence":"All the samples were cooled from 30 to−100 °C. As shown in Figure 2a−c, the intensities of most of crystalline bands for all three P3HP samples increase distinctively with cooling.","label":"POLY_STRUC"}
{"id":193,"sentence":"Another significant point observed in Figure 3 is that the splitting bands at 801 and 806 cm−1 for the γ−form have very close temperature dependences,","label":"POLY_STRUC"}
{"id":194,"sentence":"8 The band at 1325 cm−1 resulted from the asymmetric stretching of the CH2 group in the PBS backbone. The band at 1712 cm−1 resulted from the C O stretching vibration of the ester group in PBS.","label":"BIODEGRAD_POLY"}
{"id":195,"sentence":"The initial PDI for both diameter fibers was 2. 0.The samples aged at 40 °C showed only a slight increase in the PDI. This indicates that the degradation occurred by random scission of the chains rather than preferential degradation at the chain ends 28.","label":"BIODEGRAD_PROP"}
{"id":196,"sentence":"The yield point is usually considered to be the first maximum on the stress−strain curve, at which the applied strain rate is equal to the plastic strain rate.","label":"MECHANICAL_PROP"}
{"id":197,"sentence":"and carbonyl (CO) groups can be used as tools to study degradation. As a result of main chain scission from hydrolysis at ester linkages, terminal alcohol and carboxylic acid groups are produced, so as hydrolysis progresses, an increase in OH groups should be observed in the FTIR absorbance spectra.","label":"BIODEGRAD_PROP"}
{"id":198,"sentence":"93 J \/ g is the enthalpy of fusion of a PLA crystal of infinite size ; and XPLA is the weight fraction of PLA. In a comparison between corn and wheat starch at a particular weight ratio, there were no significant differences in the glass−transition, crystallization,","label":"POLY_STRUC"}
{"id":199,"sentence":"There was no longer a peak at 1722 cm−1, indicating the absence of ester bonds which is due to the hydrophobic nature of PCL. This carboxylic acid is the product of PCL degradation.","label":"BIODEGRAD_POLY"}
{"id":200,"sentence":"Ltd, China, under the trade name of Biocosafe 2003F with a melting point of 117 °C. PBS pellets were supplied by the same company under the trade name of Biocosafe 1903F with a melting point of 115 °C. PP‐1350N homopolymer was procured from Pinnacle Polymers (Garyville, LA).","label":"POLY_STRUC"}
{"id":201,"sentence":"In contrast, as the γ−and β−forms have the similar conformation, i. e., the all−trans, the contribution of the intermolecular interaction is expected to be responsible for their most difference in the molecular mobility.","label":"POLY_STRUC"}
{"id":202,"sentence":"Jamshidi et al. [3] found that PLA with a molecular weight of 22, 000 g \/ mole has a Tg of 55 °C which is only 4 – 5 °C lower than that predicted for PLA of infinite molecular weight.","label":"POLY_STRUC"}
{"id":203,"sentence":"which were shifted a little to higher wave numbers compared to those of pure PLA (1745 cm−1) and PCL (1723 cm−1).","label":"BIODEGRAD_POLY"}
{"id":204,"sentence":"17 The Food and Drug Administration have approved PCL for use in medical and drug delivery devices, making it an excellent candidate for a biomaterial. 18 However, due to its hydrophobic nature, it may not be very useful in certain applications whereby a fast degradation rate is desired.","label":"BIODEGRAD_POLY"}
{"id":205,"sentence":"the crystalline regions begin to become the dominant morphology. This is consistent with the obtained crystallinity of these samples which remains constant through day 7 and then begins to rise, likely due to a combination of low molecular weight species leaching out of the samples and incorporating into the crystalline regions.","label":"POLY_STRUC"}
{"id":206,"sentence":"and then cooled to room temperature and immediately reheated to 100 °C. For PHB and PHB−V, the temperatures used were 180 and 200 °C, respectively.","label":"BIODEGRAD_POLY"}
{"id":207,"sentence":"Tg ` 0 58 °C for PLLA and 57 °C for PDLLA K 0 5. 50 * 104 for PLLA and 7. 30 * 104 for PDLLA For PLLA Jamshidi [3] presented the following equation : 1 \/ Tm−1 \/ Tm ` 0 2RM0 \/ DHmMn (14) where Tm ` 0 Tmelt at infinite molecular weight R 0 gas constant M0 0 molecular weight of the repeat unit DHm 0 heat of fusion per mole of the repeat unit A plot of 1 \/ Tm versus 1 \/ Mn should give a straight line with a slope of 2RM0 \/ DHm and an intercept of 1 \/ Tm `.","label":"BIODEGRAD_POLY"}
{"id":208,"sentence":"Lopez Arraiza et al. : Rheological Behavior and Modeling of Thermal Degradation c 2007 Carl Hanser Verlag, Munich, Germany www. polymer−process. com Not for use in internet or intranet sites.","label":"RHEOLOGICAL_PROP"}
{"id":209,"sentence":"As the cost of PLA has fallen due to increased production capacity, arenas outside of the biomedical field, such as the fiber industry, have seen an increase in the use of PLA.","label":"BIODEGRAD_POLY"}
{"id":210,"sentence":"28 and−36. 14 °C, respectively. The Tg of the block copolymers P3HP−b−29 % P4HB and P3HP−b−37 % P4HB had two values at−46.","label":"POLY_STRUC"}
{"id":211,"sentence":"The yield strength, maximum tension strength, and Young ’ s modulus of the block copolymers P3HP−b−P4HB were strongly improved over random copolymer P (3HP−co−4HB).","label":"MECHANICAL_PROP"}
{"id":212,"sentence":"the splitting pattern of individual resonances of fraction was the same as the block copolymer P3HP−b−P4HB, which indicated that there was no detectable presence of homopolymer P3HP, P4HB,","label":"BIODEGRAD_POLY"}
{"id":213,"sentence":"We monitored the hydrolysis process by means of tracking the changes in the molecular weight distribution, weight loss, water uptake, and PLA crystallinity as a function of time.","label":"BIODEGRAD_PROP"}
{"id":214,"sentence":"5 ppm. (23b) Obviously, the shielding γ−gauche effect itself could not explain the chemical shift displacement of β CH2 of P3HAs, and some distinctive deshielding effect must come along with the conformation change.","label":"BIODEGRAD_POLY"}
{"id":215,"sentence":"In contrast, the thermal degradation behavior of PCL was very complex because various reactions occurred concurrently : post−polymerization, loss of structural regularities and random chain scissions.","label":"BIODEGRAD_PROP"}
{"id":216,"sentence":"An increase in the starch content resulted in a reduction of tensile strength and elongation of the composites. The star−PLA had shown a slightly better adhesion to the starch granules than the PLLA, but the adhesion was still poor.","label":"MECHANICAL_PROP"}
{"id":217,"sentence":"which may be attributed to the fact that the PLA chains in the tri−block copolymers hinder the mobility of the PBAT segment. Moreover, the long chains of the PLA segment decrease the segmental flexibility and mobility of the PLA blocks,","label":"BIODEGRAD_POLY"}
{"id":218,"sentence":"The respect of the environment is a capital point in a sustainable development context. This kind of materials of industrial interest and low environmental impact is not within the aim of this review due to a minor biodegradability.","label":"BIODEGRAD_PROP"}
{"id":219,"sentence":"Mw (g \/ mol) Before injection molding After injection molding Before injection molding After injection molding Before twin−screw extrusion After twin−screw extrusion SEC−MALLS SEC−MALLS Dilute solution viscometry Dilute solution viscometry Dilute solution viscometry Dilute solution viscometry 53, 000 54, 500 Mv 5 187, 562 Mv 5 146, 571 Mv 5 187, 562 Mv 5 110, 654 168, 000 173, 000 Note : SEC \/ multi−angle laser light scattering used chloroform as solvent.","label":"POLY_STRUC"}
{"id":220,"sentence":"the work on P3HP likely sheds light on the crystallization and biodegradation of other P3HAs. The X−ray and \/ or electron diffraction analyses proposed that both the β−and γ−form unit cells are orthorhombic,","label":"BIODEGRAD_POLY"}
{"id":221,"sentence":"In this study, the effect of fiber diameter on the degradation characteristics of PLA fiber of two diameters, 32 μm (PLA32) and 118 μm (PLA118), aged at 40, 60, and 80 °C with 100 % relative humidity, was investigated.","label":"BIODEGRAD_POLY"}
{"id":222,"sentence":"After 18 days of continuous conditioning at 50 °C with 90 % RH, the flexural strength of PBS, PBS \/ PBAT, and PP samples was found to increase slightly.","label":"BIODEGRAD_POLY"}
{"id":223,"sentence":"It is generally agreed that the amorphous region is more susceptible for hydrolysis than crystalline regions in semicrystalline polymers. Therefore, these findings have good agreement with the improved percentage of crystallinity which was observed by DSC.","label":"POLY_STRUC"}
{"id":224,"sentence":"In this sense, the present study was aimed to investigate the effect of mechanical and physico‐mechanical properties of PBS, PBAT, and PBS \/ PBAT blend at 50 °C with 90 % relative humidity for duration of up to 30 days.","label":"BIODEGRAD_POLY"}
{"id":225,"sentence":"Anaerobic respiration : several microorganisms are unable to use oxygen as the final electron acceptor. Fermentation : some microorganisms lack of electron transport systems. Fermentation, an incomplete oxidation pathway, is their sole possibility to produce energy.","label":"BIODEGRAD_PROP"}
{"id":226,"sentence":"Different amounts of tri−block copolymers were added to the immiscible PLA \/ PBAT system as compatibilizers. Compared to the short−chain PLA blocks (LPB),","label":"POLY_STRUC"}
{"id":227,"sentence":"It has been shown by Witzke and Nijenhuis [60, 62] that the apparent rate of propagation will increase and the apparent equilibrium monomer concentration will decrease when crystalline polymer domains form during polymerization.","label":"POLY_STRUC"}
{"id":228,"sentence":"Neat PBS and PBAT were dried in an oven for 6 h at 80 °C to remove the moisture prior to melt processing. Sample Preparation and Conditioning Neat PP, PBS, PBAT,","label":"BIODEGRAD_POLY"}
{"id":229,"sentence":"and (70 \/ 30) decreased to 0.77 and 0.69, respectively, after 30 min at 190 °C, whereas those of compatibilized PLA \/ PCL (90 \/ 10)","label":"BIODEGRAD_POLY"}
{"id":230,"sentence":"Compositional Changes of PCL‐b‐PEG Copolymer Film 1H‐NMR analysis was carried out to determine the changes in composition of PEG and PCL segments as the degradation proceeded.","label":"BIODEGRAD_POLY"}
{"id":231,"sentence":"and shear rate. Under the same processing conditions, semi−crystalline PLA had a higher shear viscosity than amorphous PLA. As the temperature increased, the shear viscosity decreased for both types of PLA.","label":"RHEOLOGICAL_PROP"}
{"id":232,"sentence":"Similarly, the PLA32 fibers showed an increase in crystallinity from 11 to 16 % for both temperatures. Both diameter fibers showed an unexpectedly high crystallinity of ∼42 % at 90 days when degraded at 60 °C with nitrogen purge.","label":"BIODEGRAD_PROP"}
{"id":233,"sentence":"The mechanical, morphological, thermal, and rheological properties were studied with the aim of evaluating the effect of compatibilization. PLA (grade 4032D, Mn 0 ∼100, 000 g \/ mol) was purchased from Natureworks. PBAT (Ecoworld,","label":"BIODEGRAD_POLY"}
{"id":234,"sentence":"One of the biodegradable and compostable polymers that has potential in commercial use is poly (butylene adipate−co−terephthalate) or PBAT, due to its ease of processing and similar mechanical properties to polyethylene [2].","label":"BIODEGRAD_POLY"}
{"id":235,"sentence":"C and 50 rpm. Then PLA fibers were pulled from the extruder to a spinner rotating at a speed of 150 rpm. Finally PLA fiber reinforced PBAT composite was manufactured by compression moulding at 130.","label":"BIODEGRAD_POLY"}
{"id":236,"sentence":"The torque ratio of the same material at different temperatures can be obtained as [27, 28, 29] : (6) Viscosity, hence torque, depends on the temperature and MW.","label":"RHEOLOGICAL_PROP"}
{"id":237,"sentence":"which was considered to have been caused by chain scission [19, 29]. In addition, complex viscosities of all compatibilized blends were higher than those of the uncompatibilized blend.","label":"BIODEGRAD_PROP"}
{"id":238,"sentence":"Inc. J. Appl. Polym. Sci. 2016, 133, 44152. INTRODUCTION Polylactide (PLA) is a biobased polyester. In the last decade,","label":"BIODEGRAD_POLY"}
{"id":239,"sentence":"and 12, the calculated kinetic constants confirmed that the pH did not significantly affect the hydrolysis rate, as already mentioned previously (Figure S6 in the Supporting Information).","label":"BIODEGRAD_PROP"}
{"id":240,"sentence":"and PP are provided in our previous study. 19 Figure 5 shows the tensile strength of PBS, PBAT, PBS \/ PBAT, and PP before and after exposure at 50 °C with 90 % RH up to 30 days.","label":"BIODEGRAD_POLY"}
{"id":241,"sentence":"Germany www. polymer−process. com Not for use in internet or intranet sites. Not for electronic distribution. Fig. 7. Mechanism of thermal degradation of PCL Fig. 8.","label":"BIODEGRAD_PROP"}
{"id":242,"sentence":"9 A, a 0 b 0 90 °, and g 0 120 °. Discrete Energy Minima for PLLA Chains according to the Conformational Energy Calculations of Flory CF, degree E, kcal \/ mol State g + C g + F I 130 110 0.","label":"BIODEGRAD_POLY"}
{"id":243,"sentence":"The only shortcomings of PBS are its insufficient impact strength and gas barrier properties for certain applications. This could be overcome by physical blending with a highly flexible PBAT while maintaining biodegradability.","label":"BIODEGRAD_POLY"}
{"id":244,"sentence":"The WAXD curves of the samples were fitted through non−linear curve fitting to obtain crystallinity values (χ c, WAXD) [26]. Finally,","label":"POLY_STRUC"}
{"id":245,"sentence":"Thermal properties of the PLLA \/ starch composites were also reported. Table XXI. Solubility Parameters of Poly (Lactic Acid) Solubility parameter Determination method (cal0.5 3 cm21.5)","label":"BIODEGRAD_POLY"}
{"id":246,"sentence":"which are rigid materials, while those from carbon chain length of C6 – C14 belong to the family of medium chain length (mcl) PHA that possess elasticity.","label":"POLY_STRUC"}
{"id":247,"sentence":"Figure 7 illustrates the melting enthalpy and Tm as a function of the molecular weight during hydrolysis at all temperatures. The melting enthalpy was increased by hydrolysis for both aPLA and cPLA.","label":"POLY_STRUC"}
{"id":248,"sentence":"R is the ideal gas constant, and Ts is a reference temperature at which the conformational entropy of the polymer chains becomes zero. This reference temperature is often considered to be 50 °C below the Tg. 18, 24 Another influential parameter on PLA hydrolysis is the acidity of the media.","label":"POLY_STRUC"}
{"id":249,"sentence":"Unoriented Orienteda Ultimate tensile strength (psi 3 103, MPa) 6. 9 – 7. 7, 47. 6 – 53. 1 6. 9 – 24, 47. 6 – 166 Tensile yield strength (psi 3 103, MPa) 6. 6 – 8. 9, 45. 5 – 61.","label":"MECHANICAL_PROP"}
{"id":250,"sentence":"As indicated by the IR results, the γ−form is involved in some stronger intermolecular interaction, which of course stabilizes the γ−form much more.","label":"POLY_STRUC"}
{"id":251,"sentence":"Our results show that the hydrolysis has an overall Δ G ⧧ of just 12. 9 kcal \/ mol, showing that the chemistry step is already very efficient.","label":"BIODEGRAD_PROP"}
{"id":252,"sentence":"Interestingly, the impact strengths of compatibilized blends were markedly higher than those of uncompatibilized blends. More specifically, the impact strengths of compatibilized PLA \/ PCL (90 \/ 10)","label":"MECHANICAL_PROP"}
{"id":253,"sentence":"(Scherer et al., 1999). However, in several studies on polyester biodegradation, some authors adopt another nomenclature, they use the abbreviated name of the polyester followed by “ depolymerase ” ; for instance, PBSA depolymerase (Zhao et al., 2005), enzyme fragmenting the poly (butylene succinate−co−butylene adipate) ; PCL depolymerase (Murphy et al., 1996,","label":"BIODEGRAD_PROP"}
{"id":254,"sentence":"and PBS \/ PBAT before and after 30 days conditioned at 50 °C and 90 % RH. CONCLUSIONS The hydrolytic degradation of PP, PBS, PBAT,","label":"BIODEGRAD_POLY"}
{"id":255,"sentence":"Poly (lactic acid) quickly loses its thermal stability when heated above its melting point. A significant level of molecular degradation occurred when PLA was held 10 °C above its melting point (160 °C) for a sustained period of time.","label":"BIODEGRAD_POLY"}
{"id":256,"sentence":"and PHB−b−PHHx. (35) Due to the distinguished properties of P3HP and P4HB, block copolymerization of these two PHA polymers could produce new material properties not yet seen in random copolymerization, blend polymers,","label":"BIODEGRAD_POLY"}
{"id":257,"sentence":"The stress concentration ability of crystallites has been increased with an enhanced percentage of crystallinity. Consequently, this could lead to a reduction in the impact strength.","label":"POLY_STRUC"}
{"id":258,"sentence":"All the triblock copolymer samples were first incubated in the TGA furnace at 100 °C under nitrogen atmosphere for 30 min and then cooled down to 30 °C to remove moisture effects before temperature scanning.","label":"POLY_STRUC"}
{"id":259,"sentence":"and poly (ethylene glycol) (PEG) was studied at pH 7. 4 and pH 9. 5 at 37 °C. The degradation of these films was characterized at various time intervals by mass loss measurements, GPC,","label":"BIODEGRAD_POLY"}
{"id":260,"sentence":"Figure 5 Complex viscosity curves of pure PLA (▲), pure PCL (△), compatibilized PLA \/ PCL (90 \/ 10) (○), uncompatibilized PLA \/ PCL (90 \/ 10) (○), compatibilized PLA \/ PCL (70 \/ 30) (■),","label":"BIODEGRAD_POLY"}
{"id":261,"sentence":"On the contrary, the spectrum (Figure 2 (d)) of the separated component from the compatibilized blend displayed strong absorption bands corresponding to C 0 O stretching of both PLA and PCL at 1746 and 1725 cm−1, respectively,","label":"BIODEGRAD_POLY"}
{"id":262,"sentence":"4 s 12. 03 31023 J \/ m2 13. 6 31023 J \/ m2 Kishore and Vasanthakumari determined the nucleation parameters for poly (L−lactic acid) crystallization from nonisothermal thermal analysis experiments using DSC [107] (Table IV).","label":"BIODEGRAD_POLY"}
{"id":263,"sentence":"Poly (butylene adipate−co−terephthalate) or PBAT resin was purchased from BASF (Florham Park, N. J., USA). PBAT film was produced using a Killion KLB 100 blown film single screw extruder manufactured by Davis−Standard, LLC, (Pawcatuck,","label":"BIODEGRAD_POLY"}
{"id":264,"sentence":"the values of the longest T1Cs for both the α CH2 and β CH2 rank as β ≪ γ ≪ δ. With taking into account that the δ−form crystal is little thinner than the β and γ crystals, while the latter two almost have no difference in the crystalline thickness, (5d)","label":"POLY_STRUC"}
{"id":265,"sentence":"Nonradical reactions of PLA degradation presented by McNeill and Leiper [20] [b], [20], [20] [a]. Temperature leads to PLA macroradicals formation that react with oxygen, developing peroxyl macroradicals (3a and 3c).","label":"BIODEGRAD_POLY"}
{"id":266,"sentence":"The thermo−mechanical and thermo−oxidative degradation of PLA was evaluated. Coupling several characterization techniques, it was concluded that PLA is more sensitive to thermo−mechanical degradation,","label":"BIODEGRAD_PROP"}
{"id":267,"sentence":"Thus, it was concluded that the sample S3 was a mixture of little amount of block P3HP−b−P4HB accompanied by homopolymers of P3HP and P4HB as dominant components.","label":"BIODEGRAD_POLY"}
{"id":268,"sentence":"H, homopolymer P3HP ; B, block copolymer P3HP−b−P4HB. The microstructures of block copolymer P3HP−b−P4HB, random copolymer P (3HP−co−4HB) and blend of P3HP and P4HB are quite different (Figure 1).","label":"BIODEGRAD_POLY"}
{"id":269,"sentence":"Poly (L−lactide) (PLLA) and poly (e−caprolactone) (PCL) are members of an interesting family of biodegradable polymers.","label":"BIODEGRAD_POLY"}
{"id":270,"sentence":"The most widely used method for improving PLA processability is based on melting point depression by the random incorporation of small amounts of lactide enantiomers of opposite configuration into the polymer (i. e., adding a small amount of D−lactide to the L−lactide to obtain PDLLA).","label":"BIODEGRAD_POLY"}
{"id":271,"sentence":"Specifically, at temperatures above the glass transition temperature, but below the melting temperature, the effect of fiber diameter on the degradation characteristics of PLA is not well studied.","label":"POLY_STRUC"}
{"id":272,"sentence":"The melt−quenched PLA−b−PI−b−PLA films were prepared by taking the solvent−cast ones as the raw samples. Afterward, PET films were delaminated to obtain the quenched PLA−b−PI−b−PLA films.","label":"BIODEGRAD_POLY"}
{"id":273,"sentence":"Gel permeation chromatography (GPC) demonstrated that the molecular weights (Mw) of the block copolymer samples were the highest as compared with other similar PHA samples (Table 2).","label":"POLY_STRUC"}
{"id":274,"sentence":"and PHB−V were done using a model 204 TASC 414 \/ 3A differential scanning calorimeter (DSC) (Netzsch−Ger ä tebau, Bavaria,","label":"BIODEGRAD_POLY"}
{"id":275,"sentence":"The name of these enzymes (PHB depolymerases) was conserved even if these enzymes were found to be effective on the hydrolytic catalysis of other polyesters : poly (propriolactone), poly (ethylene adipate), poly (hydroxyacetate), poly (hydroxyvalerate), etc.","label":"BIODEGRAD_POLY"}
{"id":276,"sentence":"Terminal process parameters for the neat PLA and PLA \/ PPG composites (15 – 20 min). The relative reduction ratio of the Mw can also be introduced to indicate the degradation rate of the polymers during processing.","label":"BIODEGRAD_POLY"}
{"id":277,"sentence":"Fig. 2. Ultimate tensile strength (UTS) of of neat PLA, neat PBAT, neat PP, PLA \/ PBAT blends, and PLA fiber \/ PBAT composite. 3.","label":"BIODEGRAD_POLY"}
{"id":278,"sentence":"Quantitatively, the weight loss of aPLA observed after 10 days at pH 9 was higher, about 70 %, than the weight loss observed in distilled water or at pH 1, about 50 %.","label":"BIODEGRAD_PROP"}
{"id":279,"sentence":"This suggests that interfacial adhesion induced by hydrogen bonding was not enough to transfer exerted stress at the interface between PLA and PCL phases. Interestingly, below 2 rad \/ s,","label":"BIODEGRAD_POLY"}
{"id":280,"sentence":"Two types of PLA−PBAT−PLA tri−block copolymers were synthesized with definite structure. • The elongation of the blend with 5 % HPB compatibilizer was seven times more than that of the pristine blends. • The interfacial phase become indistinct and the size of dispersed phase decrease from 1.","label":"BIODEGRAD_POLY"}
{"id":281,"sentence":"Poly (lactic acid) can undergo cationic ring−opening polymerization. Racemization of less than 5 % was seen, starting with 99. 9 % pure L−lactide [39, 40].","label":"BIODEGRAD_POLY"}
{"id":282,"sentence":"and (70 \/ 30) increased to 1.44 and 1.60, respectively. This increase in the normalized complex viscosities of compatibilized blends indicates improved thermal stability.","label":"RHEOLOGICAL_PROP"}
{"id":283,"sentence":"and the total weight loss of the samples was calculated as follow : (5) where W0 is the initial sample weight. Similarly, the water uptake was calculated with the weight of the wiped discs after hydrolysis (Wwet)","label":"BIODEGRAD_PROP"}
{"id":284,"sentence":"Fragmentation is a lytic phenomenon necessary for the subsequent event called assimilation (cf. § Assimilation). A polymer is a molecule with a high molecular weight, unable to cross the cell wall and \/ or cytoplasmic membrane.","label":"BIODEGRAD_PROP"}
{"id":285,"sentence":"and 12. The temperature was set at 70 °C, and the hydrolysis was monitored for 10 days. Whenever the hydrolysis was performed in alkaline conditions, that is, pH 12,","label":"BIODEGRAD_PROP"}
{"id":286,"sentence":"Fig. 2 shows the temperature dependences of storage modulus, E′, loss modulus, E′′ and loss tangent, tan δ for solvent−cast PLA−b−PI−b−PLA triblock copolymers during temperature scans from the DMA measurement.","label":"MECHANICAL_PROP"}
{"id":287,"sentence":"and poor mechanical properties. Poly (lactic acid) homopolymers have a glass−transition and melt temperature of about 55C and 175 °C, respectively.","label":"POLY_STRUC"}
{"id":288,"sentence":"R2 (E \/ R) 2 (K) k02 (days−1) 89 The media effect on the hydrolysis kinetics was studied. Hydrolysis at 70 °C in three media was used to determine the kinetic parameters.","label":"BIODEGRAD_PROP"}
{"id":289,"sentence":"This observation indicates that the biodegradable polyesters (PBS, PBAT, and PBS \/ PBAT blend) can readily undergo severe degradation after being exposed to elevated humidity and temperature.","label":"BIODEGRAD_POLY"}
{"id":290,"sentence":"Fig. 3. PLA hydrolysis in acidic conditions. Photodegradation is the most efficient abiotic degradation occurring on the environment. Shyichuk et al. (2004) have introduced a model,","label":"BIODEGRAD_PROP"}
{"id":291,"sentence":"The following values were input into the equation above to obtain the aforementioned values : The peak crystallization temperature was 125 °C [107]. Kalb and Pennings [85] carried out some isothermal crystallization experiments of PLLA using optical microscopy.","label":"POLY_STRUC"}
{"id":292,"sentence":"Catalysts and oligomers decrease the degradation temperature and increase the degradation rate of PLA. In addition, they can cause viscosity and rheological changes, fuming during processing,","label":"BIODEGRAD_PROP"}
{"id":293,"sentence":"This implies that the PBS is more moisture sensitive than the PBAT and the PP. Toughness of the polymer is mainly dependent on the tie molecules and entanglement of the polymer chains. 42−44 When,","label":"BIODEGRAD_POLY"}
{"id":294,"sentence":"Mass Loss Measurements The mass loss of the polymer films after degradation was evaluated by eq. (1) : (1) where Mt and Mo were the mass at time t and initial mass, respectively.","label":"BIODEGRAD_PROP"}
{"id":295,"sentence":"Lack of a crystallization exotherm suggested that the PDLLA in the blend reached the maximum crystallization rate possible, Bigg [100] found that annealing at 3−mm−thick PLA tensile bar beyond 5 minutes at 110 °C produced no observable increase in the degree of crystallinity achieved.","label":"BIODEGRAD_POLY"}
{"id":296,"sentence":"This polymerization technique yields high−molecular−weight polymers, but with considerable catalyst impurities due to the high levels needed for acceptable reaction rates. This residual catalyst can cause many problems during further processing, such as unwanted degradation, uncontrolled or unreproducible hydrolysis rates,","label":"BIODEGRAD_PROP"}
{"id":297,"sentence":"In another study from Lyu et al., 12 acid and alkaline media were investigated for a very specific PLA synthesized from a 70 \/ 30 dd‐lactide \/ dl‐lactide monomer mix.","label":"BIODEGRAD_POLY"}
{"id":298,"sentence":"Compared to the LPB tri−block copolymer, the HPB tri−block copolymers contained relatively long chains of PLA blocks. Therefore, the spectroscopic results confirmed that PLA−PBAT−PLA tri−block copolymers with a relatively definite structure were synthesized.","label":"POLY_STRUC"}
{"id":299,"sentence":"In addition, the enhanced melt complex viscosities and storage moduli of electron−beam−treated PLA \/ PCL blends would make them suitable for applications, such as thermoforming, blow molding,","label":"RHEOLOGICAL_PROP"}
{"id":300,"sentence":"Similar observations have been reported by Harris and Lee for PLA. 14 However, after 30 days conditioning, the Tg values of the PBAT and PBS \/ PBAT reduced marginally with slightly increased in crystallinity.","label":"BIODEGRAD_POLY"}
{"id":301,"sentence":"Cellulose and PCL had very high biodegradation rate at the earlier composting period, whereas PLA had very low biodegradation rate over the entire test period. Compatibilized PLA \/ PCL blends had high biodegradation rate after 20 composting days, presumably due to the fact that, in PLA \/ PCL blends, PCL degraded first to create holes which accelerated the degradation of PLA [34, 35].","label":"BIODEGRAD_POLY"}
{"id":302,"sentence":"More specifically to say, the PLA end blocks form the glassy hard phase domains with the Tg2 values (Tg, PLA in Fig. 5b) (see Table 3) higher than the ambient temperature, whilst the crystallization of PLA end blocks can further strengthen the existing network because PLA crystals have the Tm values (Tm, PLA in Fig. 5a) in the range of 135 – 145 °C,","label":"POLY_STRUC"}
{"id":303,"sentence":"From these results, we conclude the thermal stability of PLA is improved by the addition of PCL and by the compatibilization treatment, which would provide more stable melt processing for industrial manufacturing operations.","label":"BIODEGRAD_POLY"}
{"id":304,"sentence":"However, the mass loss of about 10 % at Week 20 is still rather small, which may be explained by the fact that the copolymer is quite hydrophobic due to the larger proportion of PCL.","label":"BIODEGRAD_PROP"}
{"id":305,"sentence":"and aldD encoding dehydratase and aldehyde dehydrogenase from Pseudomonas putida KT2442, and phaC encoding PHA synthase from Ralstonia eutropha, was able to produce homopolymers 3HP and 4HB, as well as P (3HP−co−4HB) copolymer with adjustable compositions, depending on 1, 3−propanediol \/ 1, 4−butanediol (PDO \/ BDO) ratios.","label":"BIODEGRAD_POLY"}
{"id":306,"sentence":"The mechanism and polymerization variables of the tin octoate polymerization has been studied by various groups, but still considerable debate about the true mechanism remains. The interaction of time and temperature, as would be expected, was very significant since this leads to degradation reactions that will limit molecular weight and affect the reaction rate [52, 53].","label":"BIODEGRAD_PROP"}
{"id":307,"sentence":"30 When PBS is exposed to high temperature and humidity environment, the surrounding moisture can interact with ester functionality of PBS and thus can create the low molecular weight PBS through hydrolytic degradation mechanism.","label":"BIODEGRAD_POLY"}
{"id":308,"sentence":"Figure 1B shows the weight loss from fibers aged at 100 % RH. For fibers degraded at 40 °C and 100 % RH, there was little weight loss observed for either diameter.","label":"BIODEGRAD_PROP"}
{"id":309,"sentence":"Complex viscosities, normalized by their initial complex viscosities at t 0 0, are presented as a function of time for pure PLA and PCL and uncompatibilized PLA \/ PCL blends in Figure 6.","label":"BIODEGRAD_POLY"}
{"id":310,"sentence":"and 150 rpm screw speed), were analyzed. The viscosity data was calculated from the pressure profiles and the volumetric flow rate. The melt viscosity was investigated as a function of resin type, temperature,","label":"RHEOLOGICAL_PROP"}
{"id":311,"sentence":"The PLA and PLA \/ PPG composites exhibit the properties of pseudoplastic fluids. At the same shear rate, the apparent viscosity and shear stress of PLA are the highest.","label":"RHEOLOGICAL_PROP"}
{"id":312,"sentence":"The PCL segment has attained higher crystallinity due to its greater composition. On the other hand, as the PCL peak shows, the intensity of the peak increased as the period of degradation progressed.","label":"BIODEGRAD_POLY"}
{"id":313,"sentence":"This was lower than that for degradation at pH 7. 4. This suggests that degradation at pH 9. 5 could be accelerated compared to that at pH 7. 4.","label":"BIODEGRAD_PROP"}
{"id":314,"sentence":"the CH2 rocking band, which lacks serious overlap with amorphous band, was found to be the most enhanced, and the extent of this enhancement ranks in the order of β−form > γ−form ≈ δ−form.","label":"POLY_STRUC"}
{"id":315,"sentence":"Hence the rate of degradation of the chosen polymer must match the desired drug release rate. Furthermore, it is essential to determine the toxicity of the degradation products as well.","label":"BIODEGRAD_PROP"}
{"id":316,"sentence":"Therefore, it is critical to understand and determine if hydrolysis and \/ or microbial activity are the main determinants of degradation of PBAT in different compost environments.","label":"BIODEGRAD_PROP"}
{"id":317,"sentence":"This can be attributed to the post crystallization of the samples after being exposed to elevated humidity and temperature. A similar result has been found for PLA, 13 poly (hydroxybutyrate‐co‐valerate) (PHBV), 37 and homo polypropylene38 specimens when exposed to different environmental conditions.","label":"BIODEGRAD_POLY"}
{"id":318,"sentence":"and poly (ethylene glycol) (PEG) was studied at pH 7. 4 and pH 9. 5 at 37 °C. The degradation of these films was characterized at various time intervals by mass loss measurements, GPC,","label":"BIODEGRAD_POLY"}
{"id":319,"sentence":"The molecular weight change during the block copolymer P3HP−b−P4HB biosynthesis was monitored before and after addition of the second substrate PDO. Time−dependent changes of weight−average molecular weight (Mw) were observed increasing during the bacterial cultivation (Figure 7).","label":"POLY_STRUC"}
{"id":320,"sentence":"It is noted that obvious yielding can be seen for the nominal stress−strain curves of PLA−PI106k−PLA. This yielding is related to the plastic character of PLA domains because PLA shows a glass transition temperature over much above room temperature (see Table 3).","label":"BIODEGRAD_POLY"}
{"id":321,"sentence":"PLA, as well as, PCL or PPC (poly [propylene carbonate]) have a slow degradability in neutral conditions and they show a higher degradability in basic conditions than acidic ones (Jung et al., 2006).","label":"BIODEGRAD_POLY"}
{"id":322,"sentence":"In this work, we examined the effect of temperature on the biodegradation of the PCL, PHB, and PHB−V based on retention of mass by samples.","label":"BIODEGRAD_PROP"}
{"id":323,"sentence":"Lalla and Chugh [109] dissolved PLA in choloroform and measured the wavelength at which the maximum absorbance occurred. Gupta and Deshmukh [117] dissolved PLA in benzene and investigated the degradation of PLA using UV spectroscopy.","label":"BIODEGRAD_POLY"}
{"id":324,"sentence":"This enzyme is particularly interesting because it can withstand temperatures well above the glass transition of many polyesters. Our insights about the reaction mechanism are important for the design of customized enzymes able to degrade different synthetic polyesters.","label":"POLY_STRUC"}
{"id":325,"sentence":"The high Young ’ s modulus and low elongation at break of PLA limit its applications in areas requiring high toughness and stretchability [9]. The plasticization modification of PLA by citrate acid ester, epoxy soybean oil (ESO), polyethylene glycol (PEG), etc., can effectively improve the brittleness of PLA [10, 11, 12, 13, 14].","label":"BIODEGRAD_POLY"}
{"id":326,"sentence":"Migliaresi et al. [114] had shown that thermal degradation was due to chain splitting and not hydrolysis [114]. They observed molecular weight reductions greater than 50 % and concluded that large molecular weight reductions were unavoidable.","label":"BIODEGRAD_PROP"}
{"id":327,"sentence":"This enzymatic specificity may contribute to different degradation rates of biodegradable polyesters in differing compost environments. Therefore, the objective of this study was to determine the effect of the environment on the biodegradation \/ hydrolysis of aliphatic aromatic polyester (in this case PBAT).","label":"BIODEGRAD_PROP"}
{"id":328,"sentence":"and the melting enthalpy was significantly increased to approximately 52 J \/ g. Tm was further reduced to 88 °C when Mw decreased to approximately 1.","label":"POLY_STRUC"}
{"id":329,"sentence":"the low viscosity of the mixture in solution accelerated the segmental motion of PBAT and its reaction with LA, thereby guaranteeing a relatively high molecular weight and well controlled composition.","label":"RHEOLOGICAL_PROP"}
{"id":330,"sentence":"The obtained PHA was dried at room temperature for PHA film formation. (36) The concentration of 1, 3−propanediol (PDO) and 1, 4−butanediol (BDO) in the culture media were analyzed as described previously (37) using high−performance liquid chromatography (HPLC, SpectroSYSTEM,","label":"BIODEGRAD_POLY"}
{"id":331,"sentence":"In particular, the thermal degradation of PCL and PLLA is initiated by random chain scission or specific chain end scission (Aoyagi et al., 2002 ;","label":"BIODEGRAD_PROP"}
{"id":332,"sentence":"a thermoplastic polymer that has been commonly used in a broad range of applications including food packaging. However, PLA is typically brittle which limits its applications, particularly,","label":"BIODEGRAD_POLY"}
{"id":333,"sentence":"It is enhanced by the presence of moisture, lactic acid residues, and metal catalysts and oxygen ; the ester groups responsible for the biodegradation are also vulnerable to thermal degradation [2].","label":"BIODEGRAD_PROP"}
{"id":334,"sentence":"which produced P4HB. A 75 mol % of P3HP and 25 mol % of P4HB were produced in the copolymer accumulated as intracellular inclusion bodies after a total period of 72 h cultivation.","label":"BIODEGRAD_POLY"}
{"id":335,"sentence":"Because PLA is a condensation polymer, chain scission is highly dependent on the presence of water. Oligomers with up to 13 monomers are water soluble. 5 Therefore, when the PLA sample is placed in aqueous media, lactic acid and lactic acid oligomers diffuse through the material and dissolve in water.","label":"BIODEGRAD_POLY"}
{"id":336,"sentence":"Thus, the resistance and durability of the material is weakened (Bonhomme et al., 2003). They can release active chemicals as nitrous acid (e. g.","label":"MECHANICAL_PROP"}
{"id":337,"sentence":"Because the calculated values for activation energy were much greater, it suggests that the assumption that the process was reaction limited was valid. CONCLUSIONS Previous work indicates that there could be a difference in the degradation rate of the fibers based on the difference in their diameters, but those studies were performed in pH 7.","label":"BIODEGRAD_PROP"}
{"id":338,"sentence":"The spherulite morphology of the samples was analyzed at close to crystallization temperature (90 °C). Before being exposed to hydrolysis conditions, it was difficult to notice clear spherulite morphology at 90 °C for all the samples.","label":"POLY_STRUC"}
{"id":339,"sentence":"and increase of lamella thickness. In addition, the brittleness of the PBS and PBS \/ PBAT blend sample was also improved with increasing conditioning time up to 30 days, accounting for the reduction in impact toughness.","label":"MECHANICAL_PROP"}
{"id":340,"sentence":"Obviously, most of crystalline bands in the fingerprint region shift to higher wavenumber with decreasing temperature. The similar phenomenon was also observed for PE during cooling,","label":"POLY_STRUC"}
{"id":341,"sentence":"(6a) Some additional efforts are still needed for further clarifying the structure of β−form. At present, no X−ray model is available for the δ−form,","label":"POLY_STRUC"}
{"id":342,"sentence":"Well organised molecular frameworks (crystalline domains) prevent the diffusion of O2 and H2O, limiting in this way the chemical degradation. Oxidative and hydrolytic degradations on a given material are more easily performed within desorganised molecular regions (amorphous domains). PLA degradation occurs in the presence of water provoking a hydrolysis of the ester bonds.","label":"BIODEGRAD_PROP"}
{"id":343,"sentence":"According to Carrasco and co−workers [9], who processed PLA by injection moulding, only pyrolytic elimination (which is responsible for the transformation of CH – CH3 into CHCH2) can be responsible for a different ratio.","label":"BIODEGRAD_POLY"}
{"id":344,"sentence":"Both pockets are located at the interface between the α \/ β hydrolase fold and the cap domains, whereas the medium pocket has no opening to the outside of the protein and the large pocket has an opening that allows the access of the hydrolysable ester and nucleophiles to the active site of the enzyme.","label":"POLY_STRUC"}
{"id":345,"sentence":"After 12 days of conditioning, the PBS \/ PBAT blend experienced severe loss in elongation because of heavy chain scission of PBS leading to hydrolysis of the PBAT phase in the blend system.","label":"BIODEGRAD_PROP"}
{"id":346,"sentence":"and PP after and before conditioning at 50 °C and 90 % RH. Before conditioning, the PBAT showed non‐break impact strength of 211 J \/ m while PBS and PP showed complete break with impact strength of 25 and 30 J \/ m, respectively.","label":"BIODEGRAD_POLY"}
{"id":347,"sentence":"Moisture Absorption Before performing moisture absorption test, all the samples were dried at 80 °C till a constant weight is reached. The moisture absorption of the samples was calculated by taking out the samples at required time interval for the set environmental exposure conditions (50 °C and 90 % RH).","label":"BIODEGRAD_PROP"}
{"id":348,"sentence":"With respect to the PLA grade, the aPLA kinetic constants proved not to exceed 1.7 times the corresponding constants for cPLA. In general, the kinetics rates were in the same order of magnitude as those observed in other reports at similar temperatures. 11, 22 Table 2.","label":"BIODEGRAD_POLY"}
{"id":349,"sentence":"Figure 10 Cumulative biodegradation of cellulose (x), pure PLA (▲), pure PCL (△), and compatibilized PLA \/ PCL (90 \/ 10) (•)","label":"BIODEGRAD_POLY"}
{"id":350,"sentence":"The extent of crystallinity, and therefore the melting point, can easily be varied, and greatly depends on the annealing or polymerization conditions and amount of meso -,","label":"POLY_STRUC"}
{"id":351,"sentence":"0 kg \/ mol and 26. 7 kg \/ mol, respectively. Increasing the feeding ratio of LA monomer to the macro−initiator enables the Mn of the tri−block copolymers ranging from 23.","label":"POLY_STRUC"}
{"id":352,"sentence":"which limits them to microphase separation in comparison to blend polymers that do not have chemical bonding. Because of the special microstructure of block copolymers, it showed new glass transition temperatures and melting temperatures,","label":"POLY_STRUC"}
{"id":353,"sentence":"Accordingly, much of attention from a number of researchers has been devoted to replace synthetic plastics with bioplastics, such as poly (lactic acid) or (PLA), poly (3−hydroxy butyrate) or (PHB),","label":"BIODEGRAD_POLY"}
{"id":354,"sentence":"and GMA were mixed in a plastic bag before being extruded in a twin−screw corotating extruder (Ikegai, PCM−45, Japan). PLA \/ PCL blends without GMA (uncompatibilized PLA \/ PCL blends) were also prepared for comparison purposes [21]. 2. 3.","label":"BIODEGRAD_POLY"}
{"id":355,"sentence":"In contrast, PCL showed no biodegradation at room temperature after almost 300 days. In this case, differences in the chemical structure and crystallinity of the polymers had little influence on their biodegradation.","label":"BIODEGRAD_PROP"}
{"id":356,"sentence":"This was accomplished by synthesizing the PLA−PBAT−PLA tri−block copolymers by solution polymerization instead of melt polymerization in this work. Compared to melt polymerization,","label":"BIODEGRAD_POLY"}
{"id":357,"sentence":"Changes in fBA and fBT were used to determine the effects of hydrolysis on each comonomer. (2) (3) Fig. 8. 1H NMR spectrum of PBAT with aromatic peak at δ 0 8.","label":"BIODEGRAD_PROP"}
{"id":358,"sentence":"Lefaux et al., 2004). The quantity of carbon dioxide may be also determined by titrimetry. Carbon dioxide is trapped in an alkaline solution to form a precipitate.","label":"BIODEGRAD_PROP"}
{"id":359,"sentence":"95 to 1.75. Thus, the PLA block length of the tri−block copolymers could be finely adjusted by changing the feeding ratio of the monomer to the macro−initiator by solution polymerization.","label":"POLY_STRUC"}
{"id":360,"sentence":"The maximum peak temperatures (onset for Tg) and the heats of fusion in the DSC thermograms for the PLA \/ cornstarch composites are denoted in Tables XXIV and XXV.","label":"BIODEGRAD_POLY"}
{"id":361,"sentence":"As shown in Figure 1c, the doublet (1409 and 1401 cm−1) and triplet (1021, 1011, and 998 cm−1) of the δ−form both well correspond to one singlet amorphous band,","label":"POLY_STRUC"}
{"id":362,"sentence":"However, a blend of PLA and PBAT only exhibits perfect performance if the two compounds are compatible in the product. Although PBAT has carbonyl groups similar to those of PLA, low interfacial adhesion and macro−phase separation between the two polyesters would lead to immiscibility.","label":"BIODEGRAD_POLY"}
{"id":363,"sentence":"Catalyst levels can be reduced to 10 ppm or less [1, 32]. The ring−opening polymerization of lactide was first demonstrated by Carothers in 1932 [33], but high molecular weights were not obtained until improved lactide purification techniques were developed by DuPont in 1954 [34].","label":"POLY_STRUC"}
{"id":364,"sentence":"This dual‐melting endothermic increased in size after 5 days of hydrolysis and turned into a single peak after a longer hydrolysis. This single peak clearly shifted to lower temperatures between the 10th and 30th day of hydrolysis.","label":"BIODEGRAD_PROP"}
{"id":365,"sentence":"Thermoplastics from polyolefins are not biodegradable, even if some of them have prooxidant additives making them photo and \/ or thermodegradable, the assimilation of oligomers or monomers by microorganims is not yet totally proved.","label":"BIODEGRAD_PROP"}
{"id":366,"sentence":"As known, thermal degradation occurs by random chain scission reactions, depolymerization, oxidative degradation, intramolecular and intermolecular transesterifications, hydrolysis, pyrolytic elimination and radical reactions [8], [8] [a], [8] [b], [8] [c], [9].","label":"BIODEGRAD_PROP"}
{"id":367,"sentence":"Diffusion is also assisted by the plasticization effect of water, and this increases the free volume. Thin films of the samples were made by heating the sample between two transparent microscope glass slides.","label":"POLY_STRUC"}
{"id":368,"sentence":"the immersion in aqueous media led to the disappearance of the small crystallization peak and the creation of a sharper melting peak at 147 °C. Thus,","label":"POLY_STRUC"}
{"id":369,"sentence":"The chemical structure of the PCL‐b‐PEG copolymer is given in Scheme 1.Scheme 1 Open in figure viewer PowerPoint Structure of PCL‐b‐PEG used in this study.","label":"BIODEGRAD_POLY"}
{"id":370,"sentence":"which is available at wileyonlinelibrary. com.] The characteristic peaks of the PBAT can be described as follows : a sharp peak at 1710 cm−1 represents the C O functionality of the ester linkage ; the band at around 1267 cm−1 assigned to the C O group in the ester linkage ; the peak at 727 cm−1 resulted from four or more adjacent CH2 groups in the PBAT backbone.","label":"BIODEGRAD_POLY"}
{"id":371,"sentence":"For instance, the PBS and PBS \/ PBAT blend showed less number of spherulites than PBAT after 30 days exposed to hydrolysis. A similar trend has been observed in the degraded polypropylene sample.","label":"BIODEGRAD_POLY"}
{"id":372,"sentence":"the torque value of the PLA at different temperatures can be obtained, and the β value of the PLA can be calculated from Equation (6) (0.076 °C−1).","label":"BIODEGRAD_POLY"}
{"id":373,"sentence":"There have been a few studies in which the degradation at temperatures above PLA's Tg has been investigated. H ö glund et al. 27 reported degradation kinetics at 37, 60,","label":"BIODEGRAD_PROP"}
{"id":374,"sentence":"Internal biodeterioration can be evaluated by change of rheological properties (Van de Velde and Kiekens, 2002). Tensile strength is measured with a tensile tester (Ratto et al., 1999,","label":"MECHANICAL_PROP"}
{"id":375,"sentence":"Change in qualitative behaviors with radiation dose indicated that some chemical reactions, such as grafting, crosslinking, and chain scission, had been induced. As shown in Figure 3,","label":"BIODEGRAD_PROP"}
{"id":376,"sentence":"and all the tan δ curves reproduce more clearly the two peaks in the temperature range from−80 to 120 °C. The above result is apparently related to the two well separated glass transitions of PI midblock and PLA end blocks in these samples.","label":"MECHANICAL_PROP"}
{"id":377,"sentence":"In particular, the thermal degradation mechanism of PCL under non−isothermal heating was explained by concurrent scission mechanisms (Sivalingam et al., 2004). PLLA \/ PCL blends were also studied showing that the degradation of both polymers were independent of each other.","label":"BIODEGRAD_PROP"}
{"id":378,"sentence":"This result agrees with the considerable reduction in the mechanical properties of the samples after being exposed to elevated temperature and humidity. Our findings allow us to conclude that the hydrolytic degradation of biodegradable polyesters need to be reduced under high humidity and temperature for diversifying their applications.","label":"MECHANICAL_PROP"}
{"id":379,"sentence":"The durability of the polymers and composites is strongly related to the degradation mechanism. The degradation mechanism is a key factor for the lifetime prediction of polymeric materials. 12, 13 If the polymeric materials maintain their required mechanical performance at least 60 weeks at elevated temperature (50 °C)","label":"BIODEGRAD_PROP"}
{"id":380,"sentence":"Such extreme conditions could be experienced during transportation of PLA fibers, particularly in hotter climates (e. g., temperature can reach 60 °C in a tractor‐trailer in the U.","label":"BIODEGRAD_POLY"}
{"id":381,"sentence":"and PBAT (0.99 % ± 0.003 %). The observed moisture absorption difference between the PBS and PBAT may be due to polarity differences between the polymers.","label":"BIODEGRAD_POLY"}
{"id":382,"sentence":"and (70 \/ 30) blends and compared them with those of uncompatibilized blends (Figure 7). The normalized complex viscosities of uncompatibilized PLA \/ PCL (90 \/ 10)","label":"RHEOLOGICAL_PROP"}
{"id":383,"sentence":"and autocatalytic bulk erosion. 6, 7 If water diffusion is slower compared to the degradation rate, hydrolysis and weight loss occur preferentially at the surface,","label":"BIODEGRAD_PROP"}
{"id":384,"sentence":"This is attributed to the low molecular weight polymer chains leading to slow crystallization. A similar crystallization behavior for PBS has been reported after exposure to raised humidity and temperature.","label":"POLY_STRUC"}
{"id":385,"sentence":"In natural soils, polymers are degraded by a variety of microorganisms, including bacteria and fungi. There was no significant difference in the biodegradation of PHB and PHB−V aged in soil compost at 46 °C. PHB and PHB−V were totally degraded after 104 days of aging in soil compost at 46 °C and PCL degraded by 36 % in 120 days.","label":"BIODEGRAD_PROP"}
{"id":386,"sentence":"the hydrogens of 3HP (3) and 4HB (4) were clearly separated into two peaks because random distribution in the microstructure of random copolymer lead to a strong interaction between 3HP and 4HB monomer, while in the block copolymers and blend sample these separations were not observed (Figure 2).","label":"POLY_STRUC"}
{"id":387,"sentence":"and PP after and before exposure to elevated temperature and humidity. After 6 days of conditioning, the PBAT did not show any significant improvement in the flexural strength which may be due to PBAT possessing a high entanglement density.","label":"BIODEGRAD_POLY"}
{"id":388,"sentence":"After the peak, a drop in the crystallinity was observed. At 14 days, the crystallinity had fallen to 45 % for PLA32 and 52 % for PLA118.","label":"BIODEGRAD_POLY"}
{"id":389,"sentence":"Runt et al. [97] and Nijenhuis et al. [59] have reported this value to be 100 joules \/ gram for slowly polymerized, highly crystalline poly (L−lactide).","label":"POLY_STRUC"}
{"id":390,"sentence":"Figure 2 Open in figure viewer PowerPoint Changes in the molecular weight of the copolymer as a function of time at pH 7. 4 and 9. 5.","label":"POLY_STRUC"}
{"id":391,"sentence":"Figure 14 Open in figure viewer PowerPoint Loss factor peak (tan δ) of PBS, PBAT, and PBS \/ PBAT before and after 30 days exposed to 50 °C with a RH of 90 %. [Color figure can be viewed in the online issue,","label":"BIODEGRAD_POLY"}
{"id":392,"sentence":"Polypropylene glycol (PPG) and PEG, with a similar polyether structure, possess a good plasticizing effect on PLA. Piorkowska et al. [15, 16] compared the plasticizing effect of PPG on PLA with two molecular weights (MWs) of 425 and 1000 g \/ mol.","label":"BIODEGRAD_POLY"}
{"id":393,"sentence":"The phenomenon is likely caused by the presence of tri−block copolymers at the interface that interfere with the coalescence of PBAT particles. In addition, further increasing the tri−block copolymer contents gradually changes the cryo−fractured morphology of PLA \/ PBAT from sea−island morphology to a co−continous structure.","label":"POLY_STRUC"}
{"id":394,"sentence":"Table 1 lists macromolecular characteristics of the PLA−b−PI−b−PLA triblock copolymers as measured by using the high temperature gel permeation chromatography (GPC). PLA−PIxk−PLA represents the sample code, in which x stands for Mn,","label":"BIODEGRAD_POLY"}
{"id":395,"sentence":"The block copolymers possessed two Tm differing from homopolymers due to the block microstructure. The P3HP block segment in P3HP−b−29 % P4HB was shifted to a low Tm at 67. 60 °C compared with Tm of 78. 13 °C in P3HP homopolymer.","label":"POLY_STRUC"}
{"id":396,"sentence":"Only limited research works have been reported on the long term durability behaviours of biodegradable polymers under simulated environmental conditions. 13, 14, 17−19 For instance,","label":"BIODEGRAD_PROP"}
{"id":397,"sentence":"The average weight loss for both PLA32 and PLA118 fibers was ∼0.5 %. For the fibers exposed to 60 °C and 100 % RH, there was a small amount of weight gain, up to 0.4 %,","label":"BIODEGRAD_POLY"}
{"id":398,"sentence":"However, this hazardous and expensive test requires particular lab room, specific equipment, training technicians and is time consuming. However, in soil, in compost or any other complex matrix, this test is unsuitable because the released carbon dioxide may come either from the polymer,","label":"BIODEGRAD_PROP"}
{"id":399,"sentence":"and the continuous phase (PLA) and the removal of some particles from the PLA matrix. On the contrary, no voids or PCL dislodgement was observed in compatibilized blends (Figures 1 (b)","label":"BIODEGRAD_POLY"}
{"id":400,"sentence":"5 rad \/ s. Compatibilization increased the normalized complex viscosities of uncompatibilized PLA \/ PCL (90 \/ 10) and (70 \/ 30) from 0.","label":"RHEOLOGICAL_PROP"}
{"id":401,"sentence":"For any application, it is important to understand the influence of the environmental conditions on the degradation properties of a given material in order to identify new markets as well as predict the useful shelf life of the polymer of interest.","label":"BIODEGRAD_PROP"}
{"id":402,"sentence":"In this equation, scomp and s0 are the ultimate tensile strengths of the composite and the matrix, respectively. The relative mechanical properties showed that some adhesion existed between PLA and the starch granules, but the adhesion was poor.","label":"MECHANICAL_PROP"}