Effects of stress and physical ageing on nonlinear creep behavior of poly(methyl methacrylate)
The effects of stress, ageing time and ageing temperature on creep behavior of poly(methyl methacrylate) were studied.After annealing above its glass transition temperature for a period of time to eliminate the stress and thermal history, the specimens were quenched and aged at various ageing temperatures for different ageing time, and then the short-term creep tests under different stress levels were carried out at room temperature. The creep swains were modeled by means of time-ageing time equivalence and time-stress equivalence, and the master creep curves were constructed via ageing time shift factors and stress shift factors. The results indicate that the creep rate increases with stress, while decreases with ageing time, and the ageing temperature history obviously affects the creep rate. For linear viscoelastic material, the ageing shift rate is independent on imposed stress, while for nonlinear viscoelastic material, the ageing shift rate decreases with increasing stress. The unified master creep curve up to 540 d at reference state was constructed by shifting the creep curves horizontally along the logarithmic time axis to overlap each other. It is demonstrated that the time-stress equivalence, united with the time-ageing time equivalence, provides an effective accelerated characterization technique in the laboratory to evaluate the long-term creep behavior of physical ageing polymers.
creep time-stress equivalence time-ageing time equivalence physical ageing polymer
ZHAO Rong-guo(赵荣国) CHEN Chao-zhong(陈朝中) LI Qi-fu(李其抚) LUO Wen-bo(罗文波)
Institute of Rheological Mechanics, Xiangtan University, Xiangtan 411105, China; Key Laboratory of L Institute of Rheological Mechanics, Xiangtan University, Xiangtan 411105, China
国际会议
长沙
英文
582-588
2008-09-28（万方平台首次上网日期，不代表论文的发表时间）