Lightweight and Strong Pp/Talc/Ptfe Foams with Enhanced Flame-Resistant Performance Fabricated by Microcellular Foam Injection Foaming

With the ever-increasing demand of plastic structural components, weight reduction plays a critical role in material-saving and environment-protection. Foam injection molding (FIM) shows a promising prospect for manufacturing lightweight products, and thus, it has never been more essential in fabricating foamed polypropylene (PP) parts by FIM due to its huge usage. However, it is challenging to produce high-performance FIM-PP foams due to its low melt strength. Herein, a novel method to prepare lightweight and strong ternary PP foams with promoted flame-resistant properties by incorporating in-situ fibrillated PTFE and talc. Because the PTFE nanofibrils and talc effectively improved the melt viscoelasticity and crystallization of PP, both the regular and mold-opening foam injection molded (MOFIM) ternary PP foams exhibited refined cellular structures. Furthermore, the MOFIM-PP/Talc/PTFE foam presented unexpectedly mechanical performance, including a 300% increase in tensile toughness, a 352% increase in notched impact strength, and a 98% increase in flexural strength, ascribed to the enhanced brittle-to-plastic transition by PTFE nanofibrils and refined cellular structure. Additionally, the flame-resistance of the MOFIM-PP/Talc/PTFE foam was also increased. Thereby, this cost-efficient, scalable, and green process to manufacture lightweight and strong PP foams with advanced flame-resistant properties could greatly broaden potential applications of PP as structural components