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Polyethylene oxide enhances the ductility and toughness of polylactic acid: the role of mesophase.
Soft Matter ( IF 2.9 ) Pub Date : 2020-06-26 , DOI: 10.1039/d0sm00671h
Zhen Wang 1 , Chuang Zhang , Zhen Zhang , Xin Chen , Xiaohui Wang , Mingjie Wen , Bin Chen , Wei Cao , Chuntai Liu
Affiliation  

A lack of understanding of the structure–property relationship of the polylactic acid (PLA)-based polymer composite system makes it a challenge to manufacture products with optimized mechanical performance by precisely regulating the microscopic structure and morphology. Herein, we chose the PLA/polyethylene oxide (PEO) blend as a model to investigate the structural reason for the enhanced ductility and toughness of this kind of material. We have demonstrated that a considerable amount of the PLA mesophases exist in the melt quenched films that display high ductility and toughness, in contrast to the PLA crystals in their counterparts of slowly cooled films that are dominated by brittle fracture. The mesophase formed by melt quenching is attributed to a moderate acceleration of PLA chain mobility due to the plasticizing effect of the flexible PEO. In situ experiments have revealed the further formation of oriented mesophases induced by tensile deformation, which presents a high consistency between the content increase and the tensile stress intensification. We illustrate that the mesophases directly develop into a microfibrillar morphology to transmit the external stress and prevent crack propagation under deformation. This work emphasizes the essential role of the PLA mesophase in acquiring the enhanced ductility and toughness of the PLA/PEO composite films, which may be generalized to other similar PLA-based polymer composite materials.

中文翻译:

聚环氧乙烷可增强聚乳酸的延展性和韧性:中间相的作用。

缺乏对基于聚乳酸(PLA)的聚合物复合系统的结构-性能关系的理解,这使得通过精确调节微观结构和形态来制造具有最佳机械性能的产品成为一项挑战。在这里,我们选择PLA /聚环氧乙烷(PEO)混合物作为模型,以研究这种材料的延展性和韧性提高的结构原因。我们已经证明,与以脆性断裂为主的缓慢冷却的薄膜中的PLA晶体相反,在具有高延展性和韧性的熔融淬火薄膜中存在大量的PLA中间相。熔融淬火形成的中间相归因于柔性PEO的增塑作用,PLA链迁移性的适度加速。原位实验揭示了由拉伸变形引起的取向中间相的进一步形成,这在含量增加和拉伸应力增强之间呈现出高度一致性。我们表明,中间相直接发展成微原纤维形态,以传递外部应力并防止变形下的裂纹扩展。这项工作强调了PLA中间相在获得PLA / PEO复合膜增强的延展性和韧性方面的重要作用,这可以推广到其他类似的PLA基聚合物复合材料。
更新日期:2020-08-05
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