Optimization of silane modification and moisture curing for EPDM toward improved physicomechanical properties

The silane modification by melt mixing and the subsequent moisture curing of ethylene propylene diene terpolymer (EPDM) was optimized based on the Design of Experiments (DOE). The optimum moisture-cured Si-EPDM samples displayed a 101.7% and 36.5% improvement in the tensile strength and modulus, respectively, compared to the pristine EPDM. The cured Si-EPDM even had higher tensile strength than the conventionally sulphur-vulcanized EPDM. Overall, the mechanical properties of the cured Si-EPDM mainly depended on the crosslinking density. However, when there was too much crosslinking, the uneven distribution, byproduct-induced defects and restrictions to the chain re-orientations would negatively affect the tensile strength. The optimum moisture-cured Si-EPDM also displayed higher thermomechanical properties than the pristine EPDM.