Effect of Molecular Weight and Orientation on Fatigue Crack Propagation of Polyimide Resin
Effect of Molecular Weight and Orientation on Fatigue Crack Propagation of Polyimide Resin
复制标题
分子量和取向对聚酰亚胺树脂疲劳裂纹扩展的影响
DOI：
10.1299/kikaia.65.2293
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
A. Morita
中科院分区：
文献类型：
--
作者：
M. Notomi;K. Kishimoto;T. Shibuya;H. Inaba;A. Morita
研究了分子量和取向对聚酰亚胺（PI）裂纹扩展性能的影响。制备了分子量为2.5×104 g/mol ~ 3.8×104 g/mol的四种样品。裂纹扩展阻力随着Mw的增加而增加。断裂表面上观察到不连续裂纹扩展（DCG）带，除了具有最高Mw的试样。高Mw时DCG消失的原因可归因于延展性的降低。DCG带的宽度几乎是恒定的，直到DCG过渡到连续裂纹扩展。Dugdale模型给出的循环加载银纹临界应力随Mw的增加而减小，这是因为银纹区的损伤不断累积直至断裂。微型CT试样的结果表明，当裂纹扩展方向垂直于PI分子链取向时，裂纹扩展阻力增大。
The effects of molecular weight and orientation on crack propagation property of polyimide (PI) are investigated. The specimens which have four kinds of molecular weight (Mw) from 2.5×104 g/mol to 3.8×104 g/mol are prepared. The crack propagation resistance increased with increasing Mw. The discontinuous crack growth (DCG) bands were observed on the fracture surfaces except for that of the specimen with the highest Mw. The reason that the DCG disappears for high Mw is attributable to the decrease of ductility. The width of DCG bands is almost constant until transition of DCG to continuous crack growth. The critical craze stress for cyclic loading given by Dugdale model decreases with the increase of Mw since the damage of the craze region is accumulated until breaking down. From the results of miniature CT specimens, the crack propagation resistance increased when the direction of crack propagating was perpendicular to the orientation of PI molecular chains.