聚丙烯挤出发泡中的关键技术——发泡体系的性能和发泡机理研究

从聚丙烯挤出发泡体系的性能包括聚丙烯熔体的黏弹性、发泡剂的溶解度和扩散系数、聚丙烯的结晶行为和成核剂的性能以及聚丙烯挤出发泡的气泡成核机理和气泡增长机理系统介绍了聚丙烯挤出发泡中的一些关键技术。研究表明：具有显著应变硬化行为和高熔体强度的长链支化聚丙烯是获得优质PP发泡材料的前提；发泡剂的溶解度和扩散系数、聚丙烯的结晶行为和成核剂的种类和性能对发泡材料的泡孔密度、泡孔尺寸和泡孔尺寸分布有显著影响；气泡成核和气泡增长机理对于聚丙烯挤出发泡的配方设计、工艺确定和设备选型具有极其重要的意义。

Key Technologies Used in Extrusion Foaming of Polypropylene--Review on Properties of Foaming System and Foaming Mechanisms

The key technologies used in the extrusion foaming of polypropylene were introduced based on the properties of foaming system and foaming mechanisms, focusing on the viscoelasticity of polypropylene melt, solubility and diffusivity of blowing agents, crystallization behavior of polypropylene, as well as cell nucleation and bubble growth mechanisms. The research results showed that the long-chain branched polypropylene with remarkable strain hardening behavior and high melt strength was the premise in the production of excellent polypropylene foam. The cell density, cell size and cell size distribution of polypropylene foam were influenced remarkably by the solubility and diffusivity of blowing agents, crystallization behavior of polypropylene, kinds and properties of nucleating agents. It was very useful of the appropriate cell nucleation and bubble growth mechanisms for formula design, processing technologies and extrusion line selection.