Abstract Hydrolytic behaviors of poly(lactic acid) (PLA) films with different crystallinities (∼0, 30 and 40%) containing hydrophobic fluoropolymers were studied by evaluating the hydrophobicity and water absorption through measuring contact angle and FTIR, and by investigating the evolution of average molecular weights, morphology and thermal property. The results showed that the hydrophobic fluoropolymers enhanced the hydrophobicity of the surface of PLA, where water contact angle increased about 20°, but they did not cause a decrease in water absorption in the bulk of PLA. The hydrolytic rate of samples was affected by both crystallinity of the PLA component and dispersion of the hydrophobic fluoropolymers. For amorphous samples, the fluoropolymers could well disperse in the PLA substrate and accelerate the hydrolysis of PLA component. The amorphous PLA had a hydrolytic rate of 0.0335 week−1, while the rate of the amorphous sample with hydrophobic fluoropolymers increased up to 0.0458 week−1. For the crystallized samples, neat PLA hydrolyzed faster than the blends. For example, the rate of PLA crystallized at 90 °C was 0.0423 week−1 while the values of the blends with PLA-b-PFMA10 and PLA-b-PFMA20 were 0.0325 and 0.0260 week−1, respectively. The difference between the blends was related to the dispersion of the fluoropolymers that the badly-dispersed fluoropolymer had better hydrolytic resistance effect than that of the well-dispersed fluoropolymer.

中文翻译：

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疏水性含氟聚合物和结晶度对聚乳酸水解降解的影响

摘要 通过测量接触角和 FTIR 评估疏水性和吸水率，并研究了不同结晶度（~0%、30% 和 40%）的含疏水性含氟聚合物的聚乳酸 (PLA) 薄膜的水解行为，并研究了平均分子量、形态和热性能。结果表明，疏水性含氟聚合物增强了 PLA 表面的疏水性，其中水接触角增加了约 20°，但它们并未导致 PLA 本体的吸水率降低。样品的水解速率受 PLA 组分的结晶度和疏水性含氟聚合物的分散度的影响。对于无定形样品，含氟聚合物可以很好地分散在 PLA 基材中并加速 PLA 组分的水解。无定形 PLA 的水解速率为 0.0335 周-1，而具有疏水性含氟聚合物的无定形样品的水解速率增加至 0.0458 周-1。对于结晶样品，纯 PLA 比共混物水解得更快。例如，PLA 在 90 °C 结晶的速率为 0.0423 周-1，而与 PLA-b-PFMA10 和 PLA-b-PFMA20 共混物的值分别为 0.0325 和 0.0260 周-1。共混物之间的差异与含氟聚合物的分散有关，分散差的含氟聚合物比分散良好的含氟聚合物具有更好的抗水解效果。例如，PLA 在 90 °C 结晶的速率为 0.0423 周-1，而与 PLA-b-PFMA10 和 PLA-b-PFMA20 共混物的值分别为 0.0325 和 0.0260 周-1。共混物之间的差异与含氟聚合物的分散有关，分散差的含氟聚合物比分散良好的含氟聚合物具有更好的抗水解效果。例如，PLA 在 90 °C 结晶的速率为 0.0423 周-1，而与 PLA-b-PFMA10 和 PLA-b-PFMA20 共混物的值分别为 0.0325 和 0.0260 周-1。共混物之间的差异与含氟聚合物的分散有关，分散差的含氟聚合物比分散良好的含氟聚合物具有更好的抗水解效果。