SYNTHESIS OF THERMOPLASTIC ELASTOMER USING POTASSIUM PERSULFATE AND AMMONIUM PEROXYDISULFATE INITIATOR

Abstract

Thermoplastic elastomer is polymeric material that has elastomer and thermoplastic properties. This material can be easilymolded into finished and recyclable goods, thus environmentaly safe for long term application. In this study we synthesize thermoplastic elastomer using two initiator that are potassium persulfate and ammonium peroxydisulfate with natural rubber to monomer (styrene/methyl methacrylate) ratio of 50 : 50 and 60 : 40 (v/v). The process of thermoplastic elastomer synthesis was conducted with emulsion grafting polymerization method for 6 hours at 65 °C. We used sodium dodecyl sulfate as emulsifier. FT-IR analysis result shows that grafting process had already occured shown by new peaks that were observed in 1743 and 1519 cm -1 . These peaks was assigned to carbonyl (C=O) group of methyl methacrylate and C=C benzene of styrene respectively. From 1H-NMR new peaks at δ = 7.1 ppm was aromatic proton from phenyl group of styrene, at δ = 3.5 ppm was methoxy proton of grafted methyl methacrylate acrylic group, and at δ = 5.1 ppm that is resonance of isoprene methyne proton. This result showed that methyl methacrylate and styrene had alrady grafted onto natural rubber backbone. Initiator influenced grafting efficiency. Potassium persulfate gave 97.6% grafting efficiency while ammonium peroxydisulfate gave 90.2% grafting efficency. Keywords: Thermoplastic elastomer, Grafting, Emulsion polimerization, Initiator, Emulsifier.