Recycling of EPDM waste. I. Effect of ground EPDM vulcanizate on properties of EPDM rubber

Processing, cure characteristics, and mechanical properties of EPDM rubber containing ground EPDM vulcanizate of known composition were studied. Moone y viscosity increases and Mooney scorch time decreases by the addition of t he ground vulcanizate. At higher loadings of the ground rubber, the maximum rheometric torque decreases. On addition of ground waste, stress-strain pr operties and tear resistance increase, whereas heat buildup marginally incr eases, resilience marginally decreases, low-strain modulus remains constant , and abrasion resistance decreases. The interplay between the filler effec t of the ground EPDM and the crosslink density changes of the EPDM matrix i s believed to be the reason for the variation in mechanical properties. It is believed that sulfur migration occurs from the raw EPDM matrix (R-EPDM) to the ground waste EPDM (W-EPDM) particle while accelerator migration occu rs from W-EPDM to R-EPDM. (C) 2001 John Wiley & Sons, Inc.