INFLUENCE of MOLECULAR Weight of Dispersing Agent ON PROPERTIES of NATURAL RUBBER/Nanosilica Composites

This research aims to study influence of molecular weight of dispersing agent on mechanical and thermal properties of natural rubber/nanosilica composites prepared by self assembly nanocomposite and latex compounding techniques. The dominated interaction of this system is an electrostatic attractive interaction between positive and negative charges. The assembly of natural rubber latex and silica nanoparticle is core shell structure by using polyeletrolyte, polydiallydimethylammoniumchloride (PDDA) as a dispersing agent that has a different molecular weight: 100,000-200,000 (low), 200,000-350,000 (medium) and 400,000-500,000 (high). This work is divided into two parts, preparing silica/PDDA aqueous suspension and preparing natural rubber/nanosilica composites. In the first step, silica nanoparticle and PDDA are prepared in aqueous suspension by ultrasonic probe. The ratios of silica/PDDA aqueous suspension are studied in various concentrations. For each PDDA concentration, the optimum of silica/PDDA aqueous suspension ratio is determined. It is able to observe dispersion of silica in aqueous suspension by using particle size  distribution (PSD). The second step, silica/PDDA aqueous suspension and natural rubber latex are mixed together, and then casted on glass plate to obtain composite films with various ratios of natural rubber/nanosilica. The silica nanoparticles are uniformly distributed in natural rubber matrix. Dispersion of silica in the composites is investigated by using scanning electron microscope (SEM). Tensile and tear resistance of the composites are tested. In addition, thermogravimetric analyzer (TGA) is applied for thermal/thermooxidative resistance.