Preparation and molecular dynamics simulation of 3-isocyanatopropyltrimethoxysilane-modified sisal microcrystalline cellulose/natural rubber composites

As a biodegradable and renewable polymer with excellent physical and chemical properties, cellulose occupies an important position in the preparation of environmentally friendly bio-based composite materials. In this study, microcrystalline cellulose (MCC) was extracted from sisal and modified using 3-isocyanatopropyltrimethoxysilane (IPMS) to obtain MCC-g, which was used to partially replace silicon dioxide (SD) in natural rubber (NR) composites. Modification reduced hydroxyl groups on the surface of cellulose and introduced aliphatic chains, which enhanced the interfacial interaction between MCC-g and NR. Experimental characterization and molecular dynamics simulation results demonstrated that this modification method effectively improved both MCC dispersion in the NR matrix and interfacial bonding. When MCC-g replaced up to 50% of SD at a filler loading of 20 phr, the mechanical properties of the composites were maintained or enhanced. Notably, the hardness, tensile strength, tear strength, and 100% tensile strength of the composites exhibited increases of 11.11%, 15.74%, 20.71%, and 43.95%, respectively. This behavior indicates that the partial substitution of SD by MCC-g has a strengthening effect on NR composites. These findings provide new design ideas for cellulose surface modification and broaden the applicability in preparing green composites. Graphical abstract