Material propertiesDevelopment of eco-friendly coupling agent for precipitated silica filled natural rubber compounds

An environmental friendly surface modification of precipitated silica with zero emission of free alcohol during the mixing process was carried out by the use of a xanthate reaction. After modification, the result was a zinc salt of dixanthated silica (ZMS). The success of ZMS preparation is evidenced by Fourier transform infrared spectroscopic results, in which a new absorption peak of the CS stretching vibration of dixanthate is observed, and by energy dispersive X-ray spectrometer (EDS) results in which the two new elements (sulphur and zinc) can be detected. Compared to the unmodified silica (UMS), the ZMS possesses smaller agglomerate size and gives superior dispersion when incorporated into a natural rubber matrix. The enhancement of filler dispersion increases with increasing degree of xanthation. Moreover, the systems reinforced with ZMS demonstrate significant increase in cure efficiency, and thus enhancement in mechanical properties of the rubber vulcanisates.