Surface-treated short sisal fibers and halloysite nanotubes for synergistically enhanced performance of polypropylene hybrid composites

Polypropylene (PP) composites were prepared by reinforcing with suitable hybrid fillers such as short sisal fibers treated with an alkali and high-intensity ultrasound (HIU) and halloysite nanotubes (HNTs) modified with 3-aminopropyltriethoxysilane. The synergistic effect of surface-treated short sisal fibers and silane-grafted HNTs were systematically evaluated through morphological, mechanical, dynamic mechanical, and thermal characterization. Alkali and HIU treatments of short sisal fibers drastically enhanced the interaction between sisal fibers and silane-grafted HNTs, which improved the interfacial adhesion between the filler system and the PP matrix. Scanning electron microscopic images indicated the continuity and smoothness of the hybrid composite surfaces. Dynamic mechanical analysis confirmed improved interactions between the hybrid filler system and the matrix, leading to significantly enhanced storage modulus in the hybrid composites. Therefore, the interfacial adhesion between the fillers and the matrix plays a significant role in improving the mechanical, dynamic mechanical, and thermal properties of polymer composites.