Graft Copolymerization Of Fluorinated Acrylate Monomer Onto Natural Rubber Latex

Abstract

The incompatibility and phase separation of fluorinated acrylate polymer/natural rubber (NR) blend was obtained due to polarity mismatch of polymeric constituents in the blend. To decrease the phase separation in the composite, the graft copolymerization was a favorite method to enhance the compatibility of the blends. In this study, 2,2,2-trifluoroethyl methacrylate (TFEMA) was grafted onto NR backbone, which was assisted by methyl methacrylate (MMA) acting as a co-monomer for enhancing the grafting efficiency (GE). The graft copolymerization was carried out by emulsion-grafting process via free radical using potassium persulphate (KPS) as an initiator. The grafting properties were investigated as a functions of initiator concentration, MMA/TFEMA wt ratio, reaction temperature and reaction time. Under the optimum conditions (condition: 50/50 (w/w) of MMA/TFEMA, 0.75 phr of KPS at 60 °C for 4 h) the obtained gross graft NR (GNR) contained the maximum %GE and grafted TFEMA content as 23.6% and 7.3 mol%, respectively, with 3.8% gel content. The chemical structure of GNR after soxhlet extraction was analyzed by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and nuclear magnetic resonance spectroscopy (NMR). The morphology of GNR latex characterized by using transmission electron microscopy (TEM) was core-shell type. The graft product was then blended with PTFEMA to form modified PTFEMA films. The compatibility testing between polymeric constituents in the films was observed via Molau test and atomic force microscope (AFM). Water and hexadecane contact angles, surface energy and analysis of mechanical and thermal properties of the obtained films were also examined. It was observed that the addition of GNR provided the better surface and mechanical properties of the modified PTFEMA films than that of non-grafted NR.