Enhanced mechanical properties, thermal behavior and foaming ability of PP‐g‐MAH modified PP/BF composites

Abstract The mechanical properties of fiber‐reinforced polymer composites strongly depend on its interfacial bond strength and fiber content, and their further lightweight is the current urgent demands for industry. Basalt fiber (BF), as an emerging natural and environmental‐friendly material, possess a broad application prospect as it can replace glass fiber. Herein, strong PP/BF composites with excellent heat deflection temperature and enhanced impact performance were successfully prepared, which augmented with the increase of BF content. The effect of PP grafted with maleic anhydride (PP‐g‐MAH) on the interfacial bonding properties between BF and PP was investigated based on the PP/20BF composite system, which was significantly improved due to the reaction of maleic anhydride polar groups with the hydroxyl groups on the BF surface. The incorporation of PP‐g‐MAH led to 24.7%, 46.9%, and 77.2% increase in tensile strength, flexural strength and impact strength of PP/20BF composites, respectively. Moreover, the crystallization properties, rheological behavior and thermal stability of the composites were significantly enhanced, which all contributed to the refinement and densification of cellular structure. The cell size was reduced from 36.38 to 13.41 μm after the addition of PP‐g‐MAH with an opening distance of 2 mm, and the cell density was enhanced by nearly one order of magnitude to 6.43 × 10⁷ cells/cm³. The cellular structure further lightens the weight of product and promotes the lightweight development of PP/BF composites.