化学-应力耦合流变试验确定PC制品的开裂时间

Cracking Time of PC Products Based on Chemical-stress Coupled Rheological Test

基于化学探测法检测聚碳酸酯(PC)制品残余应力的原理,为确定退火后PC试件的环境应力开裂时间,开展了一系列化学溶液浸渍-四点弯曲应力松弛耦合状态下的流变试验。采用自主研制的可进行四点弯曲松弛和蠕变试验的流变试验仪,获得了不同松弛初始应力下PC退火试件在空气、正丙醇及正丙醇-甲苯混合溶液等不同环境中的开裂时间,建立了不同溶剂环境下流变松弛初始应力与开裂时间之间的非线性回归方程。研究结果表明:PC试件的开裂时间与流变松弛初始应力、外界化学环境有关;残余应力主导着PC注塑制品内部结构的劣化,而外界化学环境将加剧其劣化。该耦合流变试验法可快速获取退火试样在某一溶液环境中的开裂时间,能满足残余应力高精度测试的要求。

In order to determine the environment stress cracking time of PC products after annealing,a series of chemical solution impregnation-stress relaxation coupling rheological experiments were carried out based on the principle of chemical detection. Cracking time of PC annealed products with different initial stress were obtained by adopting the self-developed rheological test instrument which can be used for four-point bending relaxation and creep test,which was in air,n-propanol and mixed solution of n-propanol and toluene. Then,non-linear regression equations between initial stress and cracking time were established under different solvent environment. Results show that the cracking time of PC products are related to initial stress and external chemical. Residual stress dominates the deterioration of the internal structure PC injection molding products,while the external environment will aggravate the deterioration. The coupling rheological test can quickly obtain cracking time of annealed products in solution environment,which can meet the requirement of high-precision test of residual stress.