Different thermal analysis techniques were used to study the effect of fillers and ionic liquids (ILs) on the vulcanization process, thermal and dynamic mechanical properties of acrylonitrile-butadiene elastomer (NBR). The products of the studies were composites of NBR filled with hydrotalcite, nanosized silica or carbon black. ILs such as 1-butyl-1-methylpyrrolidinium (BMpyrrolBF 4), 1-butyl-4-methylpyridinium (BMpyrBF 4) or 1-butyl-1-methylpiperidinium (BMpipBF 4) tetrafluoroborates were applied to improve the dispersion degree of the curatives and filler particles in the elastomer and to increase the efficiency of vulcanization. The differential scanning calorimetry results indicated that ILs reduced the vulcanization temperature of NBR compounds and increased the homogeneity of cross-link distribution in the elastomer network. NBRs filled with carbon black or silica exhibited similar thermal stabilities, whereas hydrotalcite reduced the temperature of thermal decomposition. The lowest mechanical loss factors were determined for vulcanizates filled with nanosized silica.

This work concerns the effect of fillers and ionic liquids on the cure characteristics of natural rubber (NR) compounds, as well as the mechanical and thermal properties of the vulcanizates. Three types of white filler were applied, such as cellulose, nanosized silica and hydrotalcite, to modify the performance of NR composites. Additionally, ionic liquids (ILs) with bromide anion and different cations, i.e., 1-butyl-3-methylimidazolium (Bmi) and 1-butyl-3-methylpyrrolidinium (Bmpyr), were used to improve the cure characteristics of NR compounds and functional properties of the vulcanizates. The type of filler and the structure of ILs were proved to affect the rheometric properties and cure characteristics of NR compounds as well as the performance of the NR vulcanizates. Owing to the adsorption of curatives onto the surface, silica reduced the activity of the crosslinking system, prolonging the optimal vulcanization time of NR compounds and reducing the crosslinking degree of the elastomer. However, silica-filled NR exhibited the highest thermal stability. Hydrotalcite increased the crosslink density and, consequently, the mechanical properties of the vulcanizates, but deteriorated their thermal stability. ILs beneficially influenced the cure characteristics of NR compounds, as well as the crosslink density and mechanical performance of the vulcanizates, particularly those filled with silica. Cellulose did not significantly affect the vulcanization of NR compounds and crosslink density of the vulcanizates compared to the unfilled elastomer, but deteriorated their tensile strength. On the other hand, cellulose improved the thermal stability and did not considerably alter the damping properties of the vulcanizates.

Organic zinc salts and complexes were applied as activators for sulfur vulcanization of styrene–butadiene elastomer (SBR) in order to reduce the content of zinc ions in rubber compounds as compared with conventionally used zinc oxide. In this article, the effects of different organic zinc activators on the curing characteristics, crosslink densities, and mechanical properties of SBR as well as the aging resistance and thermal behavior of vulcanizates are discussed. Organic zinc salts seem to be good substitutes for zinc oxide as activators for sulfur vulcanization of SBR rubber, without detrimental effects to the vulcanization time and temperature. Moreover, vulcanizates containing organic zinc salts exhibit higher tensile strength and better damping properties than vulcanizate crosslinked with zinc oxide. The application of organic zinc activators allows the amount of zinc ions in SBR compounds to be reduced by 70–90 wt % compared to vulcanizate with zinc oxide. This is very important for ecological reasons, since zinc oxide is classified as being toxic to aquatic species.

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Ionic liquids (ILs) are increasingly used in elastomer technology due to unique physico-chemical properties, which are stable at the temperature of preparation and during processing of rubber compounds. The latest IL application concept is supported ionic liquid-phase (SILP) materials, where an IL film is immobilized on the solid phase. The main aim of this work was studying the influence of IL immobilized on the surface of solid supports, such as silica and carbon black, on the vulcanization process, mechanical properties, and thermal behavior of ethylene–propylene–diene (EPDM) elastomer. Application of the SILP materials enabled the control of EPDM vulcanization without deterioration of the crosslink density, damping properties, thermal stability, and resistance of the vulcanizates to thermo-oxidative aging. Slight improvements in the tensile strength and hardness of the vulcanizates were observed.

The goal of this work was to apply ionic liquids (ILs) with bis(trifluoromethylsulfonyl)imide anion (TFSI) for fine-tuning the cure characteristics and physico-chemical properties of elastomer composites based on a biodegradable natural rubber (NR) matrix. ILs with TFSI anion and different cations, such as alkylpyrrolidinium, alkylammonium, and alkylsulfonium cations, were applied to increase the efficiency of sulfur vulcanization and to improve the performance of NR composites. Thus, the influence of ILs on the vulcanization of NR compounds, as well as crosslink density and physical properties of NR vulcanizates, including tensile properties, thermal stability, and resistance to thermo-oxidative aging was explored. The activity of ILs seems to be strongly dependent on their cation. Pyrrolidinium and ammonium ILs effectively supported the vulcanization, reducing the optimal vulcanization time and temperature of NR compounds and increasing the crosslink density of the vulcanizates. Consequently, vulcanizates with these ILs exhibited higher tensile strength than the benchmark without IL. On the other hand, sulfonium ILs reduced the torque increment owing to the lower crosslinking degree of elastomer but significantly improved the resistance of NR composites to thermo-oxidation. Thus, TFSI ILs can be used to align the curing behavior and performance of NR composites for particular applications.

Ionic liquids (ILs) are widely used in elastomer composites, primarily as vulcanization activators or accelerators, crosslinkers, conductive additives, or dispersing agents of fillers. The aim of this work was to study the efficiency of ionic liquid immobilization on filler surfaces using different techniques of thermal analysis and scanning electron microscopy (SEM). Ionic liquid, such as 1-decyl 3-methylimidazolium bromide (DmiBr) was grafted on the surface of silica, calcium oxide, and carbon black to improve the dispersion degree of their particles in the elastomeric matrix. Thermal analysis and SEM microscopy revealed a key role in determining the efficiency of the filler modification with ILs dissolved in acetone. Identifying the weight loss associated with thermal decomposition of DmiBr in modified fillers, allowed the calculation of the efficiency of their modification and compare the surface reactivity of studied fillers with DmiBr. Silica and carbon black exhibited high and comparable ability for interaction with ionic liquid. SEM images showed that particles of DmiBr-modified fillers were quite homogeneously dispersed in the elastomer matrix and exhibited good adhesion to the elastomer.