Compatibility enhancement of silica and natural rubber compound using UVA-induced silane-grafted saponified skim natural rubber
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Silane coupling agents are potential reagents widely used to improve the compatibility between silica and less polar rubber, especially natural rubber (NR). Nevertheless, high temperature is generally required to generate the interaction between the components during the mixing process. Accordingly, an alternative method by grafting the silane coupling agent onto the rubber molecules would be a desirable approach to develop a compatibilizer for the silica-filled NR compound. In this work, skim NR was used as a starting material due to its linear structure. The optimal conditions of the grafting reaction were found to be 1 phr of an alkoxy silane and 5 phr of benzoyl peroxide under 8 min of UVA irradiation time. These conditions were applied for producing the rubber material used in the mixing process of STR 5L and silica. The cure characteristics, silica dispersion and mechanical properties of the rubber compounds were improved, suggesting that the modified rubber was an efficient material for increasing the compatibility between silica and NR.
KeywordsSkim natural rubber Silica Silane coupling agent UVA-induced grafting reaction
The authors would like to acknowledge for the financial support from the Thailand Research Fund (TRF) through IRG5780009 and the basic research grant: BRG5780002. The Center of Excellence for Innovation in Chemistry, Commission on Higher Education (PERCH-CIC) is also acknowledged. Sincere appreciation is extended to Thai Rubber Latex Co., Ltd. for kind support the NR latex.
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