The mobility of the amorphous phase in polyethylene as a determining factor for slow crack growth.

摘要: Polyethylene (PE) pipes generally exhibit a limited lifetime, which is considerably shorter than their chemical degradation period. Slow crack growth failure occurs when are used in long-distance water or gas distribution though being exposed to pressure lower the corresponding yield stress. This slow characterized by localized craze and fibril rupture. In literature, lifetime of PE often considered as determined density tie chains connecting adjacent crystalline lamellae. But this consideration cannot explain excellent durability recent bimodal grade for pipe application. We show paper importance length determining factor lifetime. The conclusions drawn from stress analysis. It found that longer fibrils sustain deformed lesser degree. mobility amorphous phase control amount material can be “sucked” thus fibrils. monitored dynamic mechanical analysis measurements. Excellent agreement between derived lifetimes materials FNCT (full notch creep test) given, providing an effective means estimate considering well-defined physical properties.