Understanding the Behavior of the Coupling Agents TESPT and Si 363 in Short-cut Aramid Fibre Reinforced Elastomers

In this study the coupling agents Bis-(triethoxysilylpropyl) tetrasulfide (TESPT) and mercaptopropyl-mono-ethoxypolyether-silane (Si 363) are compared to each other in a standard SBR formulation for adhesion-activated epoxy-coated short-cut aramid fibres. Comparing TESPT with Si 363 with the help of a design of experiments approach gives a better understanding of the relevant factors, in order to judge and to quantify the relative importance of all varied factors on measured properties. Fibre loading, the vulcanization system and the coupling agent concentration control the Young’s modulus of the elastomers most significantly. A 200 % optimization towards a higher Young’s modulus of the elastomers can be obtained by use of TESPT alone.