Investigation of γ-Aminopropyltriethoxysilane (APTES)-Modified Halloysite Nanotubes on the Reinforcement of Halloysite/Polypropylene (PP) Nanocomposites

Halloysite was successfully grafted with silane APTES using both wet and dry modification methods. Among them, wet modification using aqueous solution possessed the highest modification efficiency and grafting ratio. Morphological observations demonstrated that APTES grafting on halloysite improved both the filler dispersion and interfacial compatibility in polymer composites. The rheology and crystallization behavior indicated that silane modification improved the halloysite dispersion in the polypropylene (PP) matrix and enhanced the interfacial bonding. Furthermore, the modified halloysite also improved the thermal stability of the PP composites, showing elevated decomposition temperatures of PP. The mechanical properties of halloysite/PP nanocomposites were apparently improved with APTES modification. The filler content of the nanocomposites was finally optimized to 2% by considering trade-offs of the tensile, flexural, and Izod impact properties.