预取向聚乳酸薄膜的力学性能  

Mechanical Properties of the Pre-oriented Polylactic Acid Films

作　　者：邱贤亮 QIU Xianliang(New Materials Department,Research and Development Center,Kingfa Technology Co.,Ltd.,Guangdong 510663,China)

机构地区：[1]金发科技股份有限公司产品研发中心新材料部,广东广州510663

出　　处：《塑料工业》2024年第9期112-116,146,共6页China Plastics Industry

摘　　要：聚乳酸是一类可生物降解的环保型绿色高分子材料。通过熔体拉伸方法制备的聚乳酸薄膜有高模量、高韧性的特征,在包装领域有广泛的应用前景。研究预取向的聚乳酸薄膜的力学性能有重要的现实意义。本文采用基本断裂功法和埃林(Eyring)理论计算了样品的韧性和屈服活化能。结果发现,随着牵伸比的增加,薄膜的结晶度提升,屈服强度增加,拉伸硬化现象明显。采用基本断裂功方法研究了不同牵伸比PLA薄膜的韧性,随着牵伸比的增大,比基本断裂功逐渐增加,比非基本断裂功呈现先增加后减小的趋势。结晶度的增加抑制了内部缺陷的扩展,导致成颈-撕裂塑性功呈线性增加的趋势。慢速拉伸时,屈服破坏来自非晶区的塑性变形,屈服活化能约为13~14 kJ/mol,快速拉伸导致晶区-非晶区界面滑移,屈服活化能仅有7 kJ/mol。Polylactic acid(PLA)is a biodegradable,eco-friendly green polymer material.PLA films prepared by melt stretching exhibit high modulus and toughness,showing wide applications in the packaging industry.Studying the mechanical properties of pre-oriented PLA films has a significant practical importance.In this paper,the toughness and yield activation energy of the samples were calculated using the essential work of fracture method and Eyring theory.The results show that,with the increase of draw ratio,the film crystallinity and yield strength increase,and the strain hardening phenomenon becomes evident.The toughness of PLA films with different draw ratios was studied using the essential work of fracture method.As the draw ratio increases,the specific essential work of fracture gradually increases,while the specific non-essential work of fracture first increases and then decreases.The increase of crystallinity inhibits the expansion of internal defects,leading to a linear increase in the necking-tearing plastic work.During the slow stretching,the yield failure originates from the plastic deformations in the amorphous regions,producing a yield activation energy of about 13-14 kJ/mol.The rapid stretching leads to the slipping of the crystalline-amorphous interfaces,producing a yield activation energy of only 7 kJ/mol.

关 键 词：聚乳酸 熔体拉伸成型 基本断裂功 屈服活化能 

分 类 号：TQ321.2[化学工程—合成树脂塑料工业]