Influence of the Silica Specific Surface Area and Ionic Liquids on the Curing Characteristics and Performance of Styrene–Butadiene Rubber Composites

Abstract

In this work, we present the effect of silica’s specific surface area (180 m2·g−1 and 380 m2·g−1, respectively) on the crosslinking of styrene–butadiene rubber (SBR) composites, as well as their crosslink density and functional properties, such as thermal stability, damping behavior, resistance to thermo-oxidative aging, and tensile properties. Ionic liquids (ILs) with a bromide anion and different cations, i.e., 1-butyl-3-methylimidazolium (Bmi), 1-butyl-3-methylpyrrolidinium (Bmpyr), and 1-butyl-3-methylpiperidinium (Bmpip), were used to enhance the cure characteristics of SBR compounds and the functional properties of SBR vulcanizates. It was proven that apart from the silica’s specific surface area, the filler–polymer and filler–filler physical interactions have a significant impact on the vulcanization kinetics of silica-filled SBR composites. Additionally, the performed studies have shown that ILs positively affected the dispersion of silica’s particles and reduced their ability to form agglomerates in the elastomer matrix, which enhanced the functional properties of the SBR vulcanizates.

The Potential Application of Starch and Walnut Shells as Biofillers for Natural Rubber (NR) Composites

“…It is known that NR composites have poor resistance to thermo-oxidative aging as compared to most synthetic rubbers [ 67 ]. It has also been proven that some additives such as ILs or silanes can significantly affect the resistance of vulcanizates to the aging process [ 42 , 68 , 69 ]. Hence, the influence of biofillers, APTES and BmiCl on the resistance of NR vulcanizates to thermo-oxidative aging was studied in the next step of the research.…”

Bromide and Chloride Ionic Liquids Applied to Enhance the Vulcanization and Performance of Natural Rubber Biocomposites Filled with Nanosized Silica

“…According to Xue et al [ 75 ] imidazolium salts showed higher thermal stability than ILs with other cations. We have also confirmed that the presence of the unsaturated heterocyclic imidazolium ring in the cation facilitated the thermal stability compared to ILs having a saturated heterocyclic ring, i.e., a pyrrolidinium or piperidinium ring [ 56 , 64 ]. Thus, ILs with pyrrolidinium and piperidinium cation reduced the T 5% by 12–20 °C as compared to the vulcanizate without ILs.…”

“…Moreover, the crosslinking of the silica-filled rubber compound proceeded in a wider range of temperatures compared to the unfilled NR. The endset crosslinking temperature was approximately 2 °C higher than that of the unfilled benchmark, which was probably due to the fact that the filler network hampers the diffusion of heat and the components of the curing system through the elastomer matrix during vulcanization [ 53 , 55 , 64 ]. Considering the measurement error, nanosized silica did not significantly affect the enthalpy of crosslinking process compared to the unfilled NR.…”

“…Both the elastomer matrix and the additives, especially organic compounds, can decompose when heated to high temperatures, which affects the thermal stability of elastomer composites. It is known that pure ILs exhibit different thermal stability, which is mainly dependent on the structure of their cation [ 41 , 56 , 64 , 75 ]. Therefore, it was reasonable to explore the impact of ILs and their structure on the thermal stability of NR vulcanizates.…”

The Synergistic Effect of Dibenzyldithiocarbamate Based Accelerator on the Vulcanization and Performance of the Silica-Filled Styrene–Butadiene Elastomer

“…As the presented work focuses on examining the synergistic effect of accelerators in silica-filled SBR composites, the methodology typically used for elastomer composites was used in the research [31][32][33].…”