Mixed surfactants for silica surface modification by admicellar polymerization using a continuous stirred tank reactor

The objective of the present study was to investigate the use of mixed surfactants of centyltrimethyl ammonium bromide (CTAB) and polyoxyethylene octyl phenol ether (OPEO10 or Triton X-100) for admicellar polymerization using a continuous stirred tank reactor to modify the silica surface for rubber compounding application. The effects of the molar ratio of CTAB to OPEO10 and the surfactant adsorption structure were investigated to relate them to the mechanical properties of the rubber compound. For any given structure of surfactant adsorption (monolayer or bi-layer coverage), a mixed surfactant system having any molar ratio of CTAB to OPEO10 gave better mechanical properties of the rubber compound than those of the pure surfactant system of CTAB or OPEO10. From the rubber testing results, the best mechanical properties of the rubber compound were achieved at a 1:3 molar ratio of CTAB to OPEO10 with the monolayer coverage structure of surfactant adsorption. The use of the mixed surfactants was found to provide better physical properties of the rubber compound as well as to reduce the significant amount of surfactants required as compared to the pure CTAB system.