Investigating the aspect ratio and concentration of ZnO nanoparticles as a filler to improve the electrical, thermal and mechanical properties of rubber composites

This study investigates a novel method to produce ZnO nanoparticles with different aspect ratios by controlling the stirring time. As the synthesis scale increases, the size of the reaction mixture influences the particle morphology. This study further examines the impact of ZnO nanoparticles, specifically when coated with Si-69, on natural rubber (NR) composites’ mechanical and electrical properties. Characterisation through FTIR, PXRD and SEM reveals successful synthesis of ZnO nanoparticles with varying morphologies. Aspect ratio analysis indicates that reaction kinetics and temperature influence nanoparticle morphology. Si-69 surface modification is confirmed through FTIR, PXRD and SEM. Incorporation of the synthesised nanoparticles into rubber composites demonstrates enhanced electrical and thermal properties. Electrical resistivity decreases with ZnO np concentration and aspect ratio, highlighting tunable electrical conductivity without compromising mechanical performance. Si-69 capped ZnO nps consistently exhibits superior thermal conductivity across concentrations. Furthermore, compared to commercial ZnO, it exhibits improved mechanical properties and cross-linking density. Tensile and tear strength exhibit significant relationships with type and concentration of ZnO nps. Interestingly, aspect ratio has a minimal influence on mechanical properties of rubber composites. TGA shows similar breakdown patterns, with inorganic residues suggesting that ZnO and carbon black may have been present after 650 °C. The findings offer insights into tailoring ZnO-reinforced rubber composites for diverse rubber-based applications.