Functionalized halloysite nanotube-reinforced SBR/NBR nanocomposites: advancements in curing, mechanical performance, and swelling resistance

Abstract

This study explores the development of composites based on a styrene-butadiene rubber/acrylonitrile-butadiene rubber (SBR/NBR) blend matrix, reinforced with halloysite nanotubes (HNTs) and compatibilized using glycidyl methacrylate-grafted styrene-butadiene rubber (SBR-g-GMA) in the presence of styrene comonomers (SBR-g-GMA-co-St). The modified HNTs include dodecyltrichlorosilane (DTCS)-modified HNTs (D-HNTs), triacontyltrichlorosilane (C30)-modified HNTs (T-HNTs), and (3-aminopropyl) triethoxysilane-modified HNTs (A-HNTs). This study evaluates the rheological, mechanical, morphological, and swelling resistance properties of the composites, incorporating filler contents ranging from 0 to 10 phr (parts per hundred rubber). Rheometric analysis shows that as the filler content increases, there is a corresponding rise in minimum torque, maximum torque, delta torque, and cure rate index, along with a decrease in scorch time and optimum cure time. A higher filler concentration leads to increased compound viscosity, crosslink density, abrasion resistance, and vulcanizate hardness, along with improvements in compression set and swelling resistance. Tensile strength peaks at 6 phr before declining at higher filler levels. Among the modified fillers, A-HNTs exhibit the most notable enhancements in curing behavior, mechanical properties, abrasion resistance, and swelling resistance. Composites containing A-HNTs show a 167% increase in tensile strength, a 67% improvement in stress at 100% elongation, and a 78% boost in tear strength. However, elongation at break decreases by 25%, and rebound resilience drops by 40%. Unmodified HNTs exhibit the best compression set performance across all filler levels.