一种高聚物银纹损伤演化的实验研究

EXPERIMENTAL STUDY ON CRAZING DAMAGE IN POLYMERS

采用光学显微技术对高聚物蠕变条件下的银纹损伤引发和演化进行了实验观测 .通过对银纹面密度的测量 ,定义一种损伤变量 ,得到了聚甲基丙烯酸甲酯不同蠕变时间和不同应力水平下的银纹损伤值 ,并给出了一种损伤演化模型 .

Crazing is usually the precursor of brittle fracture of glassy polymers; on the other hand, it is also one of the main mechanisms of polymer toughening. An optical technique to quantify the creep crazing damage in stressed transparent glassy polymeric sheet of PMMA is presented. The specimens are loaded for a defined period of time under creep condition with room temperature, after which the areal craze densities are measured with an optical microscope. Experimental results show that crazing damage, which represented by areal craze density, increases with the applied stress and the test time. The craze damage evolution equation for PMMA under creep condition is derived theoretically and parameters in which are determined experimentally.