Influence of aramid fibers modified by glycidyl polyhedral silsesquioxane assisted with supercritical carbon dioxide on the properties of aramid fiber-reinforced styrene butadiene rubber composites

The weak interfacial adhesion of aramid fibers (AFs) in rubber composites can be improved by modifying their surface structure. Herein, modified AFs with a high grafting rate were prepared by modification using glycidyl polyhedral silsesquioxane (POSS) assisted with supercritical carbon dioxide (scCO₂). X-ray photoelectron spectroscopy confirmed the chemical bonding between AFs and glycidyl POSS. Thermogravimetric analysis and scanning electron microscopy images showed that POSS was grafted uniformly and the surface roughness enhanced obviously. After grafting the rubber with 5 wt% glycidyl POSS assisted with scCO₂, the surface grafting rate reached 12.26% and surface crystal spacing increased. The grafted layer on the modified AF surface was uniform, and the tensile strength of the modified fiber increased by 7.98%. Short AF-reinforced carbon black/styrene butadiene rubber (AF/CB/SBR = 2/50/100 phr) composites were prepared to investigate the adhesion strength between modified AFs and SBR. The reduction in tan δ of the composites confirmed the improvement in the interfacial adhesion strength. The tensile strength and modulus at 100% elongation of the composites increased by 15.13% and 25.77%, respectively, and the relative interface slip increased by 23.26%. Moreover, the cutting resistance of the composites showed a dramatic improvement, particularly for grafting with 5% glycidyl POSS assisted with scCO₂. © 2024 Society of Industrial Chemistry.