2013 Volume 49 Issue 4 Pages 112-119
The influences of alkoxy group number and loading method of silane coupling agents on the mechanical properties of a styrene-butadiene ruber/silica composite were investigated. The pre-treatment method and the integral blend method were compared. In the case of mercapto functional silane, the 200% modulus was higher in the pretreatment than in the integral blend for dialkoxytype. However, it was higher in the integral blend than in the pre-treatment for trialkoxytype. The binding of rubber molecular chains by the silane chains on the silica surface was higher in the pre-treatment for dialkoxytype, where as it was higher in the integral blend for trialkoxy type. In the pre-treatment for dialkoxy type, a linear silane chain formed in the case of multi-layer coverage. The silane chain entangled with the rubber chain and improved the reinforcement effect. In the integral blend for trial koxy type, the formation of the silane network and the entanglement progressed simultaneously during the preparation process. A well entangled interfacial region was formed. In the case of polysulfide –type silane, the pre-treatment of silane with four sulfur atoms was more effective than that with two sulfur atoms for improving the 200% modulus. The sulfur atoms in the silane should contribute to the crosslinking of rubber in the vulcanization process. The silane with much sulfur atoms strengthens the interface effectively and raises the 200% modulus. The 1H pulse nuclear magnetic resonance spectroscopy was measured for the unvulcanized rubber/silica mixture. The measured relaxation time was found to be in good correlation with the 200% modulus.
