摘要
PE气体管材在室温低应力长期作用下发生开裂破坏的过程是由较长时间的裂纹慢速增长(SCG)阶段和较短时间的快速增长阶段(FCG)构成的.通过预测SCG阶段的持续时间可以预测PE材料的使用寿命,而SCG阶段可由PE的拉伸试验和三点弯曲试验进行模拟并用Dugdale理论处理.用弯曲试验来模拟预测PE开裂破坏时间的式子为■PE的这种开裂破坏是由连结分子的解缠滑脱作用造成的.在宏观上表现为脆性断裂.它受应力、温度、试样切口深度以及分子量与分子量分布、支化情况和结晶情况等因素的影响.改变这些因素能够使断裂机理发生改变,从而改变PE材料的使用寿命.
Polyethylene gas pipe undergoes cracking and brittle failure in the neighbourhood of room temperature when a low stress is applied for a long period of time. The cracking process includes two stages, e.g. the slow crack growth (SCG) stage which takes most of the cracking period and the fast crack growth (FCG) stage which is a relatively very short period. The lifetime of PE pipe can be estimated by predicting the persistence time of the SCG stage. The SCG process can be simulated by conventional tensile test and three—point bending test of which tht failure time can be predicted using Dugdale model:
The mechanism is that the cracking, which is a brittle failure,is caused mainly by the disentanglement of the tie molecules in the amorphous zone and by the slipping out of them from the crystalline zone. The SCG process is influenced by external factors such as applied stress, temperature, and the notch depth of the sample as well degree of branching, branch length,and crystallinity.
出处
《高分子通报》
CAS
CSCD
1992年第4期218-227,共10页
Polymer Bulletin
关键词
聚乙烯
管材
裂纹
脆性断裂
polyethylene pipe
crack growth
kinetics
brittle failure
Dugdale model
