Influence of Coupling Agent on Properties of Carbon Black-Reinforced SBR and NR/SBR Vulcanizates

Influence of the coupling agent on properties of carbon black-reinforced rubber compounds and vul- canizates was studied. Four styrene-butadiene rubber (SBR) compounds with different SBR types and five NR/SBR blend compounds with different rubber compositions were compared. Bis-(3-(triethoxysilyl)-propyl)-te- trasulfide (TESPT) was used as the coupling agent. For the SBR specimens, the modulus and tensile strength were enhanced by adding the coupling agent although the elongation at break was reduced. For the NR/SBR specimens, the crosslink density and modulus were enhanced by adding the coupling agent while the bound rub- ber content was decreased. The elongation at break and tensile strength of the NR/SBR specimens with higher SBR content were enhanced by adding the coupling agent. Change of the properties of the rubber specimens by adding the coupling agent was explained with modification of the carbon black surface and donation of sulfur from TESPT.