Tough crystalline blends of polylactide with block copolymers of ethylene glycol and propylene glycol
Tough crystalline blends of polylactide with block copolymers of ethylene glycol and propylene glycol
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DOI：
10.1016/j.polymertesting.2015.06.014
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发表时间：
2015-09
期刊：
影响因子：
5.1
通讯作者：
M. Pluta;E. Piorkowska
中科院分区：
文献类型：
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作者：
M. Pluta;E. Piorkowska
研究了聚丙交酯 (PLA) 结晶度对聚乳酸 (PLA) 与 PEG-b-PPG-b-PEG 嵌段共聚物共混物结构和性能的影响。 PLA 与一组具有不同比例的亲水性 (PEG) 和疏水性 (PPG) 嵌段的共聚物熔融共混。尽管共混物相结构取决于共聚物摩尔质量和 PEG 含量以及共混物中的共聚物浓度，但结晶度也发挥了重要作用，它增加了非晶相中的共聚物含量并增强了相分离。结晶度对共混物热性能和机械性能的影响取决于所用的共聚物及其含量。该共混物的 PLA 结晶度为 25 ÷ 34 wt%，具有相对较高的玻璃化转变温度（45 至 52 °C），并在 120 °C 以上开始熔化。尽管除了少数例外，结晶度会恶化可拉伸性和韧性，但在部分混溶共混物的情况下，这些性能相对于纯结晶 PLA 得到了改善，其中改性剂的细液体夹杂物分散在富含 PLA 的基体中。在少量改性剂 (10 wt%) 下，断裂伸长率增加了约 20 倍，拉伸冲击强度增加了约 4 倍。此外，结晶度降低了纯PLA和共混物的氧气和水蒸气透过率，并且后者的氧气阻隔性能优于纯聚合物。
The effect of crystallinity of polylactide (PLA) on the structure and properties of tough PLA blends with PEG-b-PPG-b-PEG block copolymers was studied. PLA was melt blended with a set of the copolymers with varying ratio of the hydrophilic (PEG) and hydrophobic (PPG) blocks. Although the blend phase structure depended on the copolymer molar mass and PEG content, as well as on the copolymer concentration in the blend, crystallinity also played an important role, increasing the copolymer content in the amorphous phase and enhancing phase separation. The influence of crystallinity on the thermal and mechanical properties of the blends depended on the copolymer used and its content. The blends, with PLA crystallinity of 25 ÷ 34 wt%, exhibited relatively high glass transition temperature ranging from 45 to 52 °C, and melting beginning above 120 °C. Although with a few exceptions crystallinity worsened the drawability and toughness, these properties were improved with respect to neat crystalline PLA in the case of partially miscible blends, in which fine liquid inclusions of the modifier were dispersed in PLA rich matrix. About 20-fold increase of the elongation at break and about 4-fold increase of the tensile impact strength were reached at a small content (10 wt%) of the modifier. Moreover, crystallinity decreased oxygen and water vapor transmission rates through neat PLA and the blend, and the barrier property for oxygen of the latter was better than that of neat polymer.