纳米网状结构PTFE/PPC复合材料的制备及其微孔发泡结构与性能研究

Poly(propylene carbonate) (PPC), derived from CO2 and propylene oxide (PO), is known as an inexpensive and biodegradable polymer. However, the practical application of PPC has been limited by its low mechanical properties. Physical modified PPC is an important method to increase its properties. To achieve high performance PPC products, the well dispersion of reinforced filler in PPC matrix by controlled process is required. Based on our pervious research, PTFE/PPC composites with improved comprehensive properties can be obtained by forming a situ-network nanofiber structure via special mixing flow field. However, the mechanism of situ-network nanofiber structure formation is still unclear. Therefore, the aim of this project is explored forming mechanism of nanofibers, network structure nanofiber and densification of PTFE fiber during the prepared process by triple-screw extruder and microcellular foaming process, respectively. Effects of mixing flow field and foaming process on the size and dispersion of PTFE nanofiber will be investigated. Furthermore, the influence of network structure nanofibre on the mechanical properties of PTFE/PPC composites and their foaming products will be evaluated. All these research will result in illuminating the relationship between the processing conditions, morphological structure and macroscopic properties of PTFE/PPC composites. The purpose of this project is to develop a new process method to fabricate high performance PTFE/PPC composites with network structure nanofibre. Its scientific and practical valuation will promote the thermal process technology and theory of polymer.

新型生物降解材料聚碳酸亚丙酯（PPC）因其机械性能低而难以广泛应用。通过加工成型新方法调控共混改性PPC复合材料的结构与性能，是实现PPC及其制品高性能化的重要途径。在我们的前期研究中发现，加工过程中原位形成的纳米网状结构聚四氟乙烯（PTFE）纤维能有效提高PTFE/PPC复合材料的综合性能，但是具体的形成机制还有待深入开展研究。因此，本项目拟在前期的研究基础上，探究PTFE/PPC复合材料在三螺杆挤出制备和微孔发泡过程中的PTFE纤维纳米化、网状化和致密化的形成过程及演变规律，探讨制备加工流场及成型过程对复合材料中PTFE纳纤尺寸与分布的影响机制，研究纳米网状结构PTFE纤维对PPC复合材料以及微孔发泡制品力学性能的影响，阐明加工条件-形态结构-宏观性能之间相互关系，从而对纳米网状结构PTFE/PPC复合材料制备成型过程中的基本科学问题及结构性能调控提供理论依据。

针对聚碳酸亚丙酯（PPC）等新型生物降解材料因其机械性能低而难以广泛应用，本项目通过加工成型新方法调控共混改性PPC基复合材料及其发泡制品的结构与性能。研究中，首先利用高效混合设备及动态成型技术，通过加工力场和工艺参数调控，促进纳米网状结构的形成，实现网状结构PTFE纤维的纳米化，制备得到了纳米网状结构PTFE复合材料。并通过复合材料的微观结构、热性能、结晶性能、流变性能及力学性能等测试分析，阐明了纳米网状结构的形成机理及对复合材料性能的影响，证实了网状结构PTFE纤维可显著增强了PPC基复合材料的综合性能，实现聚合物材料的高性能化。进而通过超临界气体微孔发泡新方法制备高强度纳米网状结构PTFE/PPC基复合材料发泡制品，研究发现，纳米网状结构PTFE纤维有效提高了PPC等生物材料的熔体强度，极大地改善了其发泡能力，且分别采用超临界气体间歇、挤出和注塑发泡等发泡技术成功制备了PTFE/PPC基复合材料微孔制品，初步实现了高强度微孔塑料的制备。项目结合发泡理论，深入探讨了微孔发泡过程中PTFE纳米网状结构细长化致密化机理，以及纳米网状结构纤维对泡孔成核长大及结构性能的影响，并通过纳米网状结构与发泡工艺调节很好实现了PTFE复合材料微孔发泡形态结构与性能的有效调控。项目研究成果对原位纳米网状结构纤维形成，高性能聚合物材料及其微孔发泡制品的加工成型新方法，以及丰富和发展高性能纳纤增强复合材料提供了理论指导。