INFLUENCE OF THE NETWORK ON THE INTERACTION PARAMETER IN SYSTEM EPDM VULCANIZATE-SOLVENT

Swelling measurements in six organic solvents were carried out on samp les of dicumyl peroxide crosslinked ethylene-propylene-diene (EPDM) ha ving various crosslink densities. The Flory-Huggins interaction parame ter chi was determined for EPDM vulcanizates 312 and 812 as well as th eir mixture 312/812 using the Flory-Rehner equation. The results show that the chi parameter for the crosslinked polymer is greater than for the uncrosslinked one and is a linear function of the crosslink densi ty. The swelling behavior of the networks were also interpreted by the Flory-Erman theory using the structural factor F-4' to characterize t he network and its behavior during the swelling. The obtained chi valu es indicate that broadening of the molecular mass distribution, in the Gaussian region of distribution, mixture 312/812, increases interacti ons with solvents. (C) 1997 John Wiley & Sons, Inc.