Electrolyte effect to copolymer grafting of starch onto natural rubber using glow discharge electrolysis plasma (Gdep) method

Natural rubber has an important role in many applications such as tyre products due to excellent elasticity and high friction causing wear on the tire and leading to energy dissipation in the form of heat and noise. Although reinforcing both inorganic and organic fillers can be a solution, it generally needs expensive coupling agent. Finding an excellent coupling agent by considering to environmentally friendly materials and economic aspect, is an interesting study. This study reported modification of natural rubber through copolymer grafting of starch onto natural rubber latex using Glow Discharge Electrolysis Plasma (GDEP) with varying of electrolyte. The experimental indicated that the electrolytes generally give significant effect to percent yield of the hybrid natural rubber-starch product. The highest percent yield is obtained from adding KCl. Addition of the divalent salts such as MgCl2 and CaCl2 disturbs the process due to reaction the salts with stabilizing system in natural rubber latex. Addition of NaOH is able to enhance the reaction performance with considering the radical elements recombination. The starch part as polar part and the natural rubber as non polar part building up the hybrid natural rubber-starch products, correlate with hydrophilicity and degradation of the both parts. This study results in the lowest contact angle of 54.8, the highest percent yield of 8.6 %,, and the highest starch content in the product of 1.6%.