成核
材料科学
混合(物理)
微晶
丙交酯
同种类的
化学工程
高分子化学
复合材料
聚合物
共聚物
热力学
有机化学
化学
物理
量子力学
工程类
冶金
作者
Yao Ju,Zhen Zeng,Hongwei Bai,Qin Zhang,Qiang Fu
标识
DOI:10.1002/mame.202100091
摘要
Abstract The nucleation efficiency (NE) of stereocomplex crystallites (SCs) formed in asymmetric poly(L‐lactide)/poly(D‐lactide) (PLLA/PDLA) blends is generally unsatisfactory because the competition between stereocomplexation and chain mixing involved in the melt‐mixing process can cause low formation efficiency and even severe aggregation of SCs. Herein, it is attempted to achieve high‐efficient formation of finely dispersed SCs particles by designing a unique melt‐mixing procedure, where the mixing of PLLA with 0.75 wt% PDLA is first performed at elevated temperatures (far above the melting temperature of SCs) to allow the homogeneous mixing of PLLA/PDLA chains and then at a low temperature (slightly above that of homocrystallites) to permit the full stereocomplexation of the premixed chains. It is found that the SCs formed in the blends exhibit unexpectedly low NEs (e.g., 54.5%), much inferior to that (73.6%) in the counterpart without undergoing premixing. This is because the introduction of premixing leads to a remarkable deterioration in the amount of SCs particles formed, despite decreased particle size, highlighting that the direct mixing at low temperatures of 170–180 °C (about 20–30 °C lower than that used in common melt‐processing of PLA) is more effective for the construction of SCs with superior NE. The mechanisms for these striking findings are discussed.
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