English Abstract
Mechanical Properties of Silica Particles-Filled Isoprene Rubber:
Effect of Surface Treatment by Silane Coupling Agent Containing Mercapto Group

Yoshinobu NAKAMURA*1, 2,
Hiroaki HONDA*1,
Atsushi HARADA*1,
Erina KAJI*1,
Syuji FUJII*1,
Takeo IIDA*1,
Kazuya NAGATA*1,
*1Department of Applied Chemistry, Osaka Institute of Technology, Asahi-ku, Osaka, Japan
*2Nanomaterials Microdevices Research Center, Osaka Institute of Technology, Asahi-ku, Osaka, Japan
*3Laboratory of Plastics, Asahi Kasei Chemicals Corp., Kawasaki, Kanagawa, Japan Nippon Gomu Kyokaishi,(2008),81(11),454-459 Original Paper in Japanese

The surface treatment of spherical silica particles with silane coupling agent (SCA) having mercapto group was carried out.
The treated silica particles were incorporated with polyisoprene, and then vulcanized. Effects of loading amount and alkoxy group number of SCA on the stress-strain curve of the filled composite were investigated. For this purpose, the SCAs with dialkoxy and trialkoxy structures were used. The loading amount of SCA on the silica surface was varied from one to thirteen times of the amount required for monolayer coverage. The stress increased by the SCA-treatment of silica, and it was higher in the dialkoxy structure than in the trialkoxy structure. There was no significant influence of loading amount on the stress for the trialkoxy structure.
The stress was influenced strongly by the loading amount for the dialkoxy structure, and the maximum stress was observed at four times of the loading amount required for monolayer coverage. The stress had the good relation with the crosslinking density of silica-filled isoprene rubber measured by a swelling test. It was found that the reinforcement effect by the SCA treatment of silica is affected strongly both by the entanglement of siloxane chain formed by the condensation of SCA and isoprene rubber matrix and the crosslinking reaction between mercapto group of silane and isoprene rubber at the interfacial region.

(Received on May 13, 2008)
(Accepted on August 25, 2008)

Silane Coupling Agent, Rubber Silica , Interfaces, Surface Treatment, Particle-filled Composite