CURE CHARACTERISTICS OF ETHYLENE-PROPYLENE DIENE RUBBER-POLYPROPYLENEBLENDS .1. CALCULATION OF STATE OF CURE IN BLENDS CONTAINING CONVENTIONAL SULFUR CURING SYSTEM UNDER VARIABLE TIME-TEMPERATURE CONDITIONS

Various blends of polypropylene and ethylene propylene diene terpolyme r were prepared. In these blends, rubber phases were compounded with a n optimum sulfur curing system. The equivalent cure time and state of cure of the mixes were studied in the temperature range from 120 to 19 0 degrees C by a rheometer. The temperature-independent parameters (E- 1, E-2, S-1, and S-2) and specification of the temperature dependence curing rate constant (k) and induction period (t(0)) were determined. The activation energies of the crosslinking reaction are almost simila r for the virgin EPDM and EPDM/PP mixes. The value 9 Kcal/mol was cons idered sufficiently accurate for these mixes. A discussion of temperat ure-conversion factor of the mixes is also provided. (C) 1997 John Wil ey & Sons, Inc.