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Effect of chain-extenders on the properties and hydrolytic degradation behavior of the poly(lactide)/poly(butylene adipate-co-terephthalate) blends.

Dong W, Zou B, Yan Y, Ma P, Chen M - Int J Mol Sci (2013)

Bottom Line: The compatibility between the PLA and PBAT was significantly improved by in situ formation of PLA-co-PBAT copolymers in the presence of the chain-extenders, results in an enhanced ductility of the blends, e.g., the elongation at break was increased to 500% without any decrease in the tensile strength.The differential scanning calorimeter (DSC) results reveal that cold crystallization of PLA was enhanced due to heterogeneous nucleation effect of the in situ compatibilized PBAT domains.A three-stage hydrolysis mechanism for the system is proposed based on a study of weight loss and molecular weight reduction of the samples and the pH variation of the degradation medium.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China. p.ma@jiangnan.edu.cn.

ABSTRACT
Biodegradable poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends were prepared by reactive blending in the presence of chain-extenders. Two chain-extenders with multi-epoxy groups were studied. The effect of chain-extenders on the morphology, mechanical properties, thermal behavior, and hydrolytic degradation of the blends was investigated. The compatibility between the PLA and PBAT was significantly improved by in situ formation of PLA-co-PBAT copolymers in the presence of the chain-extenders, results in an enhanced ductility of the blends, e.g., the elongation at break was increased to 500% without any decrease in the tensile strength. The differential scanning calorimeter (DSC) results reveal that cold crystallization of PLA was enhanced due to heterogeneous nucleation effect of the in situ compatibilized PBAT domains. As known before, PLA is sensitive to hydrolysis and in the presence of PBAT and the chain-extenders, the hydrolytic degradation of the blend was evident. A three-stage hydrolysis mechanism for the system is proposed based on a study of weight loss and molecular weight reduction of the samples and the pH variation of the degradation medium.

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Weight loss of the examined samples as a function of degradation time: (a) PLA; (b) PBAT; (c) PLA/PBAT (80/20, w/w); (d) PLA/PBAT/ADR (80/20/1, w/w) and (e) PLA/PBAT/HDE (80/20/1, w/w).
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f6-ijms-14-20189: Weight loss of the examined samples as a function of degradation time: (a) PLA; (b) PBAT; (c) PLA/PBAT (80/20, w/w); (d) PLA/PBAT/ADR (80/20/1, w/w) and (e) PLA/PBAT/HDE (80/20/1, w/w).

Mentions: The weight loss of PLA, PBAT, and PLA/PBAT blends are shown in Figure 6. The weight loss of neat PLA is approximately 3% in the initial stage, while it increases steeply after four weeks (Figure 6a). On the other hand, the weight of the PBAT sample is relatively stable during the experimental time (Figure 6b). The trend of weight loss of the PLA matrix was not changed by addition of 20 wt % of PBAT, however the rate of weight loss of the blend was slowed down by the addition of chain-extenders (Figure 6d,e). The lower weight loss rate is resulted from the higher molecular weight of the chain-extended samples.


Effect of chain-extenders on the properties and hydrolytic degradation behavior of the poly(lactide)/poly(butylene adipate-co-terephthalate) blends.

Dong W, Zou B, Yan Y, Ma P, Chen M - Int J Mol Sci (2013)

Weight loss of the examined samples as a function of degradation time: (a) PLA; (b) PBAT; (c) PLA/PBAT (80/20, w/w); (d) PLA/PBAT/ADR (80/20/1, w/w) and (e) PLA/PBAT/HDE (80/20/1, w/w).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3821610&req=5

f6-ijms-14-20189: Weight loss of the examined samples as a function of degradation time: (a) PLA; (b) PBAT; (c) PLA/PBAT (80/20, w/w); (d) PLA/PBAT/ADR (80/20/1, w/w) and (e) PLA/PBAT/HDE (80/20/1, w/w).
Mentions: The weight loss of PLA, PBAT, and PLA/PBAT blends are shown in Figure 6. The weight loss of neat PLA is approximately 3% in the initial stage, while it increases steeply after four weeks (Figure 6a). On the other hand, the weight of the PBAT sample is relatively stable during the experimental time (Figure 6b). The trend of weight loss of the PLA matrix was not changed by addition of 20 wt % of PBAT, however the rate of weight loss of the blend was slowed down by the addition of chain-extenders (Figure 6d,e). The lower weight loss rate is resulted from the higher molecular weight of the chain-extended samples.

Bottom Line: The compatibility between the PLA and PBAT was significantly improved by in situ formation of PLA-co-PBAT copolymers in the presence of the chain-extenders, results in an enhanced ductility of the blends, e.g., the elongation at break was increased to 500% without any decrease in the tensile strength.The differential scanning calorimeter (DSC) results reveal that cold crystallization of PLA was enhanced due to heterogeneous nucleation effect of the in situ compatibilized PBAT domains.A three-stage hydrolysis mechanism for the system is proposed based on a study of weight loss and molecular weight reduction of the samples and the pH variation of the degradation medium.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China. p.ma@jiangnan.edu.cn.

ABSTRACT
Biodegradable poly(lactide)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends were prepared by reactive blending in the presence of chain-extenders. Two chain-extenders with multi-epoxy groups were studied. The effect of chain-extenders on the morphology, mechanical properties, thermal behavior, and hydrolytic degradation of the blends was investigated. The compatibility between the PLA and PBAT was significantly improved by in situ formation of PLA-co-PBAT copolymers in the presence of the chain-extenders, results in an enhanced ductility of the blends, e.g., the elongation at break was increased to 500% without any decrease in the tensile strength. The differential scanning calorimeter (DSC) results reveal that cold crystallization of PLA was enhanced due to heterogeneous nucleation effect of the in situ compatibilized PBAT domains. As known before, PLA is sensitive to hydrolysis and in the presence of PBAT and the chain-extenders, the hydrolytic degradation of the blend was evident. A three-stage hydrolysis mechanism for the system is proposed based on a study of weight loss and molecular weight reduction of the samples and the pH variation of the degradation medium.

Show MeSH