Effects of sol-gel modification on the interfacial and mechanical properties of sisal fiber reinforced polypropylene composites

Abstract

In order to prepare high performance sisal fiber reinforced polypropylene composites, this paper pays special attention to the changes of intrinsic mechanical properties of the sisal fiber so as to achieve the maximum reinforcing effect of the fiber. For achieving this aim, the sisal fibers were modified by tetraethylorthosilicate (TEOS) sol-gel method to form SiO2-based organic-inorganic hybrid materials. For a better result, a novel combined modification method by TEOS precursor solution and γ-aminopropyltriethoxysilane solution for the fibers was put forward and performed. Then the relevant mechanism was also analyzed in detail. The corresponding composites were prepared by melt blending with polypropylene matrix and polypropylene-graft-maleic anhydride (MAPP) compatibilizer, and the interfacial and mechanical properties of composites were studied by single fiber fragmentation test and mechanical test, respectively. The results show that the mechanical and thermal properties of the modified fiber composites are improved compared with the untreated fiber composite. The combined modification composite presents the highest interfacial shear strength, which increases by 259.49% compared with the untreated fiber composite. A good interfacial bonding is obviously observed in the combined modification composite by the analysis of scanning electron microscope (SEM). The tensile strength and modulus of the composite with the combined treatment (20 wt% fiber loading) increase by 21.72% and 28.18%; the flexural strength and modulus increase by 3.61% and 16.02%; and the impact strength increases by 21.28%.