Application of Grafting Method for Modification of Precipitated Silica in Rubber Compounds

Application of silica in green-tire tread compounds is limited due to polarity and hydrophilic nature of silica surface which leads to both poor rubber-filler and strong filler-filler interactions. Therefore, silica surface must be modified by organic material. In this work, liquid-rubber-grafted (LRG) silica was employed in an emulsion-SBR compound by melt mixing, and its properties were compared with commercial silane-modified and unmodified silica compounds. Using scanning electron microscopy, it was observed that both silane and LRG modified silicas disperse much better than unmodified silica due to reduction of filler-filler interactions. Mechanical properties in tension for the LRG silica compound showed higher elastic modulus at low strains, but lower values at large strains than those for silane-modified silica compounds. Tensile strength of both compounds is equally much higher than that for unmodified silica compound. Larger strain at break for LRG-silica compounds constitute higher fracture energy for the compound prepared by LRG-silica than saline modified silica. DMTA results in linear viscoelastic regime confirmed higher modulus of LRG compounds than that of silane modified compound. Loss factor in small strain mode could not differentiate filler-polymer interaction in different compounds

Keywords:

Silica , Surface Modification , Silane TESPT , Liquid Rubber , Grafting