Development of high Mooney viscosity, homogeneous long-chain branched EPDM

A study was conducted to demonstrate the development of high Mooney viscosity, homogeneous long-chain branched EPDM. It was demonstrated that the design of EPDM for sponge bulb profiles was the most demanding of all applications in automotive weatherstrip. Developmental EPDM polymers made with an advanced postmetallocene catalyst system were produced in Dow's pilot plant to conduct the investigations. The polymers had monomer compositions of amorphous, high diene polymers containing 50-55 weight % ethylene, and 7-9 weight % of ENB where indicated paraffinic processing oil was included to facilitate processing and mixing. Melt rheology data shown were generated using small angle oscillatory shear performed using a TA Instruments ARES, equipped with '25 mm parallel plates' under a nitrogen purge. The experiments were performed at 190°C, over a frequency range from 0.1 to 100 rad/s. The EPDM polymers were evaluated to demonstrate the effects of homogeneous long-chain branching on the melt rheology and compounded rubber properties.