Increasing the interaction between starch and the rubber matrix by coupling agent addition

A previous study showed that the modulus of a starch filled natural rubber (nr) compound was low compared to the carbon black filled compound and probably insufficient for many engineering applications. hence,it was considered interesting to determine whether coupling agents such as bis-(3- triethoxysilylpropyl) tetrasulfane (tespt)/si 69,polybutadiene maleic anhydride (pbmah) and resorcinol formaldehyde (rfh) resin with a methylene donor could improve starch filled vulcanisate properties,particularly by increasing the modulus. in this study,tespt/si 69 (5 p.h.r.),pbmah (5 p.h.r.) and rf/hmt (3 p.h.r./2 p.h.r.) were used as coupling agents in the starch filled compounds. it was observed that the rubber adhesion was increased by adding pbmah and rfh coupling agents and,as a result,the stiffness and the elasticity increased whilst the water absorption decreased.