Methacrylate-functionalized POSS influence on cross-linking and mechanical properties of styrene-butadiene rubber

The addition of methacrylate-functional polyhedral oligomeric silsesquioxane (MA-POSS) nanoparticles to styrene-butadiene rubber (SBR) composites was evaluated in terms of rheological, mechanical, and morphological properties. The aging process and cross-link density of rubber nanocomposites were examined in presence of MA-POSS. The MA-POSS could directly participate in the vulcanization reaction due to its methacrylate groups and its concentration affected the rheological and mechanical properties of rubber. The sulfur vulcanization characteristics of MA-POSS/SBR nanocomposites were determined by moving die rheometer. It was indicated that the addition of MA-POSS to SBR composites retarded the curing time and decreased the cross-link density. Due to an effective interaction between MA-POSS nanofiller and SBR matrix and excellent dispersion of POSS, the mechanical properties of nanocomposites were higher than those of the reference compound without MA-POSS. However, there was no significant change investigated in tensile retention in presence of MA-POSS. The presence and the random distribution of MA-POSS in SBR matrix was confirmed by TEM analysis. The cross-link densities of the composites, which were calculated using Flory–Rehner equation, decreased with increasing amount of POSS nanofiller. It was finally revealed that the thermal aging dramatically reduced the mechanical properties and cross-link density of MA-POSS/SBR nanocomposites.