聚丙烯/聚乙烯共混物超临界流体微孔发泡中黏弹性对泡孔结构的影响

Effect of Viscoelasticity on the Cellular Structure during PP/PE Blends Microcellular Foaming Using Supercritical Fluid

密度低、刚度-质量比高、冲击强度高等优点使微孔发泡塑料越来越多地应用在工程领域,然而微孔塑料加工中依旧存在着一些困难需要解决,尤其是如何控制泡孔形态。文章采用4种不同熔体指数的聚乙烯(PE)分别对PP进行共混改性,并测量其流变性能,然后利用高压釜进行微孔发泡,旨在研究不同发泡压力下,熔体黏弹性对泡孔形态的影响。结果显示:熔体强度和黏度低会使泡孔结构变差,尤其在较高的发泡压力下;而较大的熔体弹性和熔体强度更有利于形成较好的泡孔结构。

Microcellular plastic is used widly in engineering fields because of its low density,high impact strength, high stiffness-to-weight ratio and so on. However, there are still some difficulties in the foaming processing,especially in controlling the cellular morphology. Four kinds of polyethylene （PE） with different melt index were selected to investigate the effects of melt viscoelasticity on the cellular morphology under the different foaming pressure. The results showed that the low melt strength and viscosity make cellular structure deteriorative, especially under the higher foaming pressure;higher melt elasticity and strength were benefit for forming the fine cellular morphology.