摘要
本文利用扫描电镜拉伸工作台观察了聚丙烯样条(带单边切口和不带切口两种样条)在低速拉伸时的形变特征。聚丙烯样条在低速拉伸时,先产生银纹和微裂纹,裂纹方向垂直于作用力方向,继续拉伸,可见到剪切屈服变形,剪切区的微裂纹方向与作用力方向平行。聚丙烯样条剪切区的取向强化效应和微裂纹转向与作用力方向一致是聚丙烯低速拉伸时表现出韧性的两个主要因素。具有单边切口的聚丙烯样条在低速拉伸时,尖端裂缝发展可分为3个阶段,即首先在切口尖端前方产生微裂纹,形成一个椭圆形区域,接着在切口尖端前方产生微孔,并进一步形成空洞,最后尖端裂缝与空洞并合,使裂缝向前发展,最终导致样条断裂。
In this paper, SEM has been used to determine deformation characteristics of PP in low speed tension process. This study shows the direction of craze and microcrack is perpendicular to the direction of applied force on PP specimen. The shape of craze and microcrack is sawtooth-like and the craze and microcrack are easy to branch. When the specimen is yielded, the direction of craze and microcrack will change and will be parallel to the direction of applied force When the PP specimen get a sharp single edge notch, microcrack of ellipse shape form in front of the notch tip during tension. With further tension, the voids will occur in front of notch tip. Then the voids will progress and meet microerack in notch to form crack. The crack grows until fracture.
出处
《现代塑料加工应用》
CAS
1991年第3期6-12,共7页
Modern Plastics Processing and Applications
基金
国家自然科学基金
关键词
聚丙烯
拉伸
形变
性能
polypropylene tension characteristics deformation
