%0 Journal Article
%T Effects of Polarity on the Filler-Rubber Interaction and Properties of Silica Filled Grafted Natural Rubber Composites
%A Wanvimon Arayapranee
%A Garry L. Rempel
%J Journal of Polymers
%D 2013
%R 10.1155/2013/279529
%X The grafting of an olefinic monomer like acrylonitrile (AN), methyl methacrylate (MMA), and styrene (ST) onto natural rubber (NR) was carried out to enhance the polarity of the new chemical groups on the NR backbone and, in turn, to improve the filler-rubber interaction. The grafted natural rubber (GNR) produced was compounded and then vulcanization was carried out in the presence of silica as a reinforcing filler. The physical properties and aging resistance provided by the presence of the polar functional groups of the GNR composites were investigated and compared with other rubbers such as SBR, NBR, and NR. The GNRs provided significant improvements in resistance of the composites to thermal, oil, and ozone while maintaining the mechanical properties of the rubber. Therefore, these properties can be controlled as a function of the polarity of functional groups on the NR backbone. Morphological studies confirmed a shift from ductility failure to brittle with the presence of the polar group on the rubber chains. 1. Introduction Natural rubber (NR) obtained from Hevea brasiliensis is a natural biosynthesis polymer possessing excellent characteristics such as high tensile strength due to its ability to crystallize upon stretching. However, NR is highly susceptible to attack by atmospheric oxygen and ozone, and hence, its heat and ozone resistance are very poor, mainly due to the presence of the double bonds in the main chain [1]. In addition, it does not perform well when exposed to oils and hydrocarbon solvents, as a result of its nonpolar character [2]. In general, the improved products from natural rubber (NR) have potentially wide applications as a result of reinforcing by fillers such as carbon black or silica [3, 4], as well as physical blends with other polymer particles [5, 6] or chemical modification [7], thus enabling these materials to compete with synthetic rubbers. In order to increase polarity and widen the application of natural rubber, natural rubber was modified by graft copolymerization with a polar functional monomer to produce grafted natural rubber (GNR) having good thermal, oil, and ozone resistance and high tensile strength. Several studies have been carried out on the grafting of NR with various olefinic monomers like acrylonitrile (AN), methyl methacrylate (MMA), and styrene (ST) which are capable of being polymerized to produce hard plastic materials [8¨C14]. The combination of high strength and oil resistance properties of GNR with a polar functional monomer is being evaluated in such applications as oil-resistant oil handling
%U http://www.hindawi.com/journals/jpol/2013/279529/