In situ formed crosslinked polyurethane toughened polylactide
In situ formed crosslinked polyurethane toughened polylactide
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DOI：
10.1039/c3py01649h
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发表时间：
2014-01-01
影响因子：
4.6
通讯作者：
Wang, Yu-Zhong
中科院分区：
文献类型：
--
作者：
Liu, Guang-Chen;He, Yi-Song;Wang, Yu-Zhong
聚乳酸（PLA）是一种生物基聚合物，但其断裂伸长率低、冲击强度低，限制了其作为商品聚合物的广泛应用。本文采用聚乳酸（PLA）与聚乙二醇（PEG）和聚亚甲基二苯二异氰酸酯（PMDI）反应共混的方法，制备了超韧聚乳酸/交联聚氨酯（PLA/CPU）二元共混物，其中CPU分散在PLA基体中。PEG和PMDI在PLA基体中原位聚合形成了CPU，通过NCO基团与PLA端羟基的反应，PLA和CPU相之间发生了界面增容作用，傅立叶变换红外光谱证实了这一点。拉伸试验和缺口悬臂梁冲击试验的结果表明，断裂伸长率和冲击强度分别增加到纯PLA的20倍和30倍以上。系统地研究了PEG分子量（即CPU软段长度）和CPU含量对PLA/CPU共混物相形态和冲击强度的影响。当软段长度为1000-2000 g·mol ~（-1），CPU含量为20- 30wt%时，获得高冲击韧性的最佳CPU粒径为0.7- 1.0mm。通过动态力学分析，通过改变PLA和CPU组分的玻璃化转变温度，研究了分散CPU与PLA基体的相容性。结果表明，随着软段长度和CPU含量的增加，相容性增加，这主要是由于增塑作用增强。PLA/CPU共混物具有较好的韧性，可替代一些传统的石油基聚合物。
Polylactide (PLA), a biobased polymer, has a short elongation at break and low impact strength, which restricted its broad application as a commodity polymer. In this paper, super-tough polylactide/crosslinked polyurethane (PLA/CPU) binary blends with CPU dispersed in the PLA matrix were prepared by reactive blending of PLA with poly(ethylene glycol) (PEG) and polymeric methylene diphenylene diisocyanate (PMDI). The in situ polymerization of PEG and PMDI in the PLA matrix formed CPU, and the interfacial compatibilization between PLA and CPU phases occurred by the reaction of NCO groups with terminal hydroxyl groups of PLA, which was confirmed by Fourier transform infrared spectroscopy. The results of a tensile test and a notched Izod impact test suggest that the elongation at break and impact strength were increased to more than 20 and 30 times those of neat PLA, respectively. The effects of PEG molecular weight (namely soft segment length of CPU) and CPU content on the phase morphology and impact strength of PLA/CPU blends were investigated systematically. The optimum CPU particle size for high impact toughness was identified to be 0.7-1.0 mm when the soft segment length and the content of CPU were in the ranges of 1000-2000 g mol(-1) and 20-30 wt%, respectively. The compatibility between the dispersed CPU and PLA matrix was studied by dynamic mechanical analysis through the change in glass transition temperatures of PLA and CPU components. The results suggest that the compatibility increased with increasing soft segment length and content of CPU, which was mainly due to the increased plasticization effect. With improved toughness, the PLA/CPU blends could be used as substitutes for some traditional petroleum-based polymers.