【摘要】 系统地研究了退火工艺对聚乙烯(PE)管的结构和耐慢速应力开裂性能的影响。结果表明,常规PE管挤出过程中管道冷却速率不同导致管内外壁晶体完善程度不同,分布不均。通过退火处理,可有效消除管道加工过程中快速冷却造成的缺陷,促进PE晶片厚度增加,完善系带分子链。相比于未退火处理的PE管,经过3 h退火处理的PE管耐慢速应力开裂性能提高了40%。但过长的退火时间会导致系带分子由晶区拔出并重结晶,降低其在非晶区密度,使耐慢速应力开裂性能降低。更多还原

【Abstract】 This paper comprehensively investigated the effect of annealing treatment on the structure and slow cracking resistance of polyethylene( PE) pipes. The experiment results show that the different cooling rates across the thickness in the process of conventional PE pipe extrusion resulte in inhomogeneous distribution of crystals with various perfections. The annealing treatment effectively eliminates the crystal defects caused by the rapid cooling process during the pipe extrusion,increases the thickness and improves the tie chain. Compared to the unannealed PE pipe,the PE pipe annealed for 3 h has 40% increase in slow stress cracking resistance. But for too long annealing time,tie molecules are pulled from the crystal area and recrystallization,reducing its density in the amorphous zone,so that the resistance to slow stress cracking decreases.更多还原