In situ grafting onto silica surface with epoxidized natural rubber via solid state method

An in situ solid state grafting reaction between epoxidized natural rubber (ENR) and silica was performed in a Haake internal mixer. Resulting ENR-grafted silica was characterized by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) measurements. Based on these results, it was concluded the silanol groups (Si-OH) of silica caused the ring opening of ENR oxirane rings so that ENR was grafted onto the silica surface. Transmission electron microscopy (TEM) photographs showed ENR-grafted silica had better dispersibility and smaller aggregates compared with the original silica. Dynamical mechanical analysis (DMA) of vulcanized rubber compounds contained ENR-grafted silica showed the glass transition temperature (Tg) of grafted ENR molecules shifted to higher temperature, from -3 degrees C to 20 degrees C, indicating the mobility of ENR was greatly restricted. As a result, the compounds containing ENR-grafted silica have higher hysteresis, and can be applied in a much wider field, such as damping materials, tires of racing cars, and so on.