The resultsshowed that the properties improvement of NR/silica compositescan be attributed to the ring-opening reaction between the epoxygroups of ENR chains and Si-OH groups on the surfaces of silicaparticles, which can improve the dispersion of silica in the rubbermatrix and enhance the interfacial interaction between rubber andsilica. The ring-opening reaction happens not only in vulcanizationprocess but also in mixing process, and that the latter seems tobe more important due to the dual effects of mechanical force andtemperature