可注塑成型的隔离结构导电聚合物复合材料研究

The formation of segregated structure has been well demonstrated to reduce the electrical percolation threshold and improve the electrical conductivity of conductive polymer composite (CPC). Nevertheless, the available segregated CPCs could be only developed via compression molding and always presented poor mechanical performance due to the existence of interface defects between polymer domains, limiting their expansive application. In this work, a second ultralow-melt-viscosity polymer (ultralow-molecular-weight polyethylene, ULMWPE) is chosen as the flow accelerator to improve the processing fluidity of classical segregated carbon nanotube/ultrahigh-molecular-weight polyethylene (CNT/UHMWPE) composite and obtain the injection molded CNT/ULMWPE/UHMWPE composite. The segregated structure would be developed with continuous CNT/ULMWPE conductive channel surrounding the isolated UHMWPE domains, by means of the manipulating the phase morphology of the injection molded composite. The UHMWPE domains without CNT would act as “excluded volume” to significantly increase the efficient utilization of CNT to establish conductive networks, contributing to the superior electrical conductivity of the composite. The favorable compatibility between ULMWPE and UHMWPE would enhance the interface bonding of UHMWPE domains and thus improve the mechanical properties of the composite. The electrical and mechanical performance of the composite can be further optimized via the elaborative adjustment of the CNT distribution and segregated structure. Finally we can reveal the relationship between injection processing field–segregated structure–performance of the CNT/ULMWPE/UHMWPE composite, providing theoretical guidance and technical support for the preparation of high-performance segregated CPC.

导电聚合物复合材料（CPC）中形成隔离结构能明显降低导电逾渗值和提高电导率，但目前隔离结构CPC仅限于模压成型制备，且存在界面缺陷，力学性能通常不高，限制其应用。本项目拟在经典隔离结构碳纳米管/超高分子量聚乙烯（CNT/UHMWPE）中引入极低粘度第二相聚合物（超低分子量聚乙烯，ULMWPE）作流动改性剂，实现复合材料注塑成型。调控复合材料相形态结构使CNT/ULMWPE形成连续相将UHMWPE微区连接起来，构建隔离结构，其中不含CNT的UHMWPE微区起体积排除作用能提高CNT有效浓度以提高复合材料电性能，ULMWPE与UHMWPE较好的相容性能改善微区界面粘结作用以提高复合材料力学性能。精细化调控CNT分布形态及复合材料隔离结构形态，实现复合材料电性能和力学性能的进一步优化，最终建立复合材料注塑加工-隔离结构形态-性能关系，为高性能隔离结构CPC材料的开发应用提供理论基础和实验依据。

本项目针对目前隔离结构导电高分子复合材料(CPCs)存在的基本问题，设计了高压固态成型和注射成型方法，用以调控半晶型聚合物（聚丙烯PP）中隔离结构的形成，所制备的复合材料具有高电导率及优异的电磁屏蔽性能（EMI SE）。通过研究导电粒子扩散动力学过程实现隔离结构的精细化调控，探明隔离结构形态对复合材料电性能及力学性能的影响规律，建立复合材料注塑加工-隔离结构-性能关系，最终获得了具有隔离结构的导电高分子复合材料(CPC)，并在低导电粒子含量情况下实现高电导率、高EMI SE和优异力学性能，为新型隔离结构CPC的开发和应用奠定理论和实验基础。此外，考虑到可穿戴电子器件发展对高效柔性电磁屏蔽材料的需求，拓展研究了高柔性、高韧性电磁屏蔽复合材料制备及电磁屏蔽织物研究，研制了耐水洗的高性能电磁屏蔽材料。