การเสริมแรงยางธรรมชาติอิพ็อกซิไดซ์ด้วยอินซิทูซิลิกาผ่านกระบวนการโซล-เจล / ภาสวุฒิ แก้วกนกวิจิตร = In situ silica reinforcement of epoxidized natural rubber via sol-ge process / Passawut Kaewkanokvijit
The aim of this work was to synthesize the in situ silica in epoxidized natural rubber (ENR) latex using a sol-gel reaction. The effects of various parameters for the sol-gel reaction such as pH, reaction temperature, mole ratio of water to tetraethoxysilane (TEOS) and TEOS content on the silica content were investigated. ENR was prepared by the in situ epoxidation of natural rubber latex. Then, the ENR was reinforced with in situ silica via the sol-gel reaction using TEOS as a precursor. The results show that the sol-gel reaction under basic condition resulted in the ring-opening of epoxy groups whereas the sol-gel reaction under acid condition did not affect that one. The increase of the reaction temperature and TEOS content provided the increase of in situ silica content and the increase of mole ratio water to TEOS resulted in a fast equilibrium of in situ silica content and good dispersion of in situ silica in ENR matrix. The optimum condition for the sol-gel reaction in ENR was the use of TEOS 90 phr and mole ratio water to TEOS of 57.77:1 under 40 ºC for 5 days. The in situ silica content was up to 19.25% (23.85 phr). Moreover, the effects of the commercial silica and in situ silica on the physical properties (i.e. cure time, tensile properties, hardness, tear strength, heat buildup and oil and ozone resistance) of ENR vulcanizates were also investigated and compared with ENR vulcanizates. The physical properties of in situ silica filled ENR vulcanizates were higher than those of ENR vulcanizates with and without commercial silica.