The influence of accelerator/sulphur and co-agent/peroxide ratios on cure characteristic and vulcanisate properties in mixed vulcanisation of styrene butadiene rubber (SBR) was investigated in this work. Accelerator/sulphur ratio was investigated with three alternative sulphur curing systems, namely conventional, semi-efficient and efficient vulcanisation (EV) systems. Zinc dimethacrylate (ZDMA) was used as a co-agent to enhance the performance of peroxide and to provide ionic linkages. Ionic linkages contributed by ZDMA create bridges between two polymer chains. The ZDMA/peroxide ratio was varied from 2 to 10. The concentration of dicumyl peroxide was held fixed while the ZDMA content was varied. Cure characteristics, mechanical properties, dynamic mechanical properties and heat aging resistance were investigated in relation to the crosslink structure. Increasing the ZDMA/peroxide ratio significantly increased density of ionic linkages, especially in combination with the EV system. The combination of EV system with high ZDMA/peroxide ratio provided the highest ionic crosslink density and the lowest polysulphidic crosslink density: this enhanced the mechanical properties, the dynamic mechanical properties and the thermal stability of SBR vulcanisates.
In the present work, the influences of filler type and content on cure characteristics, mechanical and dynamic mechanical properties, and heat aging resistance of filled styrene butadiene rubber (SBR) compounds cured with a mixed vulcanisation system were assessed. A new mixed curing system was developed to obtain vulcanisates with excellent mechanical properties and heat aging resistance compared to those with a commercial EV cure system. The results show that filler has stronger effect on scorch time, cure time and cure rate index with the EV system than with the mixed curing system. The torque difference of filled SBR compounds depends on the filler content. With mixed vulcanisation, it is easier to control the conditions during moulding when the formulation is altered, particularly with a change in filler content. The mixed vulcanisation gave overall improved mechanical properties, heat build-up and heat aging resistance compared to the EV system, even though reinforcing fillers were used in the SBR compounds.
In this work, to study the utilization of zinc dimethacrylate (ZDMA) in sulfur vulcanized styrene butadiene rubber (SBR). The compounds were prepared by two roll mill mixer. Crosslink density and crosslink types were determined with an equilibrium swelling method. Physical properties and heat aging resistance were studied. The results shows that increase of ZDMA will decrease cure rate index and crosslink density which lead to decreased in 300% modulus and hardness. However, the addition of ZDMA can improve tensile strength, tear strength, elongation at break and heat aging resistance.
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