高聚物长时标力学行为的预测——Ⅰ.物理老化对聚丙烯长时标尺寸稳定性的依赖性

STUDY ON THE PREDICTION OF LONG-TERM MECHANICAL BEHAVIORS FOR POLYMERS——Ⅰ. Dependence of Physical Aging on the Long-Term Dimensional Stability for Polymers

用统计力学和老化反应动力学相结合的方法,求得了高聚物蠕变量同老化时间(t_a)、推迟时间系数(β)和特征时间(t_0)间的定量关系式。分析了聚丙烯的蠕变实验数据,得到了推迟时间系数(β)和特征时间(t_0)值及 t_0对 t_a 的依赖性,研究了不同老化时间对聚丙烯的粘弹性和长时标尺寸稳定性的依赖性。并提出了从主组合直线上外推法来预测聚丙烯长时标的尺寸稳定性和使用寿命。

The effect of physical aging on the viscoelasticity and the dimensional stabilityfor polypropylene(PP)was studied by the creep method.A universal creep function was derivedtheorectically by the combination of the kinetics of aging in free state and creep state.It is suc-cessful in relating the compliance D/D_0 to the aging time t_a,the average retardation time indeformated and free state(?)b,the coefficient of retardation time β and the creep time t.Based on the relation the dependence of physical aging on the demensional stability of PP wasstudied by creep method.The coefficient of retardation time,and the characteristic time t_0 forPP were determined respectively.It is found that the coefficient of retardation time is a constantfor a given temperature and polymers.A method for prediction of long-term lifetime anddimensional stability for polymers was proposed.