An Illustration: Vulcanized EPDM Systems

The importance of selecting the right coupling agent with an organofunctionality complementary to the curing/polymer system is shown below. Comparative modulus values are shown for two filled EPDM (ethylene propylene diene monomer rubber) systems cured with sulfur and peroxide respectively. In the formulation, one part per hundred parts of resin (phr) of each silane indicated was introduced during compounding of 100 phr filler in a two-roll mill, and the composite properties were determined by standard (DIN 53504) methods. Modulus of sulfur-and peroxide-cured EPDM with different silanes With regard to the sulfur-cured system, the primary amino-functional silane and the mercapto-functional silane are able to participate in the cure mechanism to a far greater extent than the vinylsilane, as shown by the higher modulus values. In the peroxide-cured system, all silanes provide significant improvements in modulus, but to different degrees - depending on their relative reactivity.