Effect of bis(diisopropyl)thiophosphoryl disulfide on the covulcanization of styrene–butadiene rubber and ethylene–propylene–diene (monomer) blends

Abstract

Covulcanization of elastomer blends constituting styrene-butadiene rubber (SBR) and ethylene-propylene-diene (monomer) rubber (EPDM) was successfully performed in the presence of reinforcing fillers like carbon black and silica by using a multifunctional rubber additive, bis(diisopropyl)thiophosphoryl disulfide (DIPDIS). The polarity of EPDM rubber was increased by a two-stage vulcanization technique, which allowed the formation of rubberbound intermediates. In this way the migration of both curatives and reinforcing fillers in the EPDM-SBR blend could be controlled and cure rate mismatch could be minimized. The process significantly improved the physical properties of the blend vulcanizates. The phase morphology, as evident from the SEM micrographs, was indicative of the presence of a much more compact and coherent rubber matrix in the two-stage vulcanizates. Different accelerator systems were studied to understand better the function and effectiveness of DIPDIS in developing homogeneity in the blends of dissimilar elastomers.

HNBR/EPDM blends: Covulcanization and compatibility

“…To date most research into the covulcanization of dissimilar rubber blends has focused on sulfur curing systems; for example, Ghosh et al studied the effect of a multifunctional rubber additive, bis(diisopropyl)thiophosphoryl disulfide (DIPDIS) on the covulcanization of SBR/EPDM, NR/EPDM, and NBR/EPDM blend systems to restrict the curative migration into the more unsaturated rubber. As a result, the cure‐rate mismatch problem could at least be ameliorated 11–13…”

Rheometric and Dynamic Mechanical Analysis of Complex Natural Rubber Based Composites

“…The lowering of the torque in the filled rubber compounds is a common fact when non-reinforcing clay, calcium carbonate and silica without silane coupling agent, such as in this case, are used as fillers [25]. The influence of the different fillers on the curing parameters is quite complex.…”

Compatibilizing effect and reinforcing efficiency of nanosilica on ethylene‐propylene diene monomer/chloroprene rubber blends

“…However, unluckily and most frequently, it has been found that the obtained material from covulcanization has a reduced mechanical strength in comparison with its expected values. [2][3][4] Ethylene-propylene diene monomer (EPDM) rubber is a terpolymer of ethylene, propylene, and a small amount of a nonconjugated diene. EPDM provides excellent resistance to weather, heat, and chemicals since it has a nonpolar structure and saturated main chain.…”

“…In order to transfer different features to a polymeric system, blending two or more rubbers can be carried out by covulcanization. However, unluckily and most frequently, it has been found that the obtained material from covulcanization has a reduced mechanical strength in comparison with its expected values 2–4 …”