Modification of Natural Rubber using Grafting Technique
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Date
2011
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
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With growing demands for new products and technologies there has been continued interest in the field of modification of rubber. A considerable amount of published information is available on the modification of synthetic and Natural Rubber (NR). Further, with increase in price of products based on petroleum, some of the synthetic rubbers which were commercially available subsequently replaced by modified natural rubbers.
Carboxylated synthetic rubbers mainly Nitrile Butadiene Rubber (NBR) and Styrene Butadiene Rubber (SBR) exist in the market. Main advantage of introducing extra carboxylic link on the synthetic rubber could be explained in terms of mechanical and physical properties of the final product.
The aim of this project was to introduce such a system (extra carbonyl group) to natural rubber, which is not available at present. The properties of natural rubber have been modified by several methods. These include, either change the chemical nature of the rubber molecule or alter its structure. A useful method of modification involves the grafting of monomers on to natural rubber backbone.
This study is based on the graft copolymerization of Methyl Methacrylate (MMA) and acrylic acid on to NR by emulsion polymerization using Tertiary Butyl Hydroperoxide(TBHP)/ Tetra ethylene Pentamine (TEP) and Potassium persulfate/ Sodium thiosulfate initiator systems, respectively. Introduction of COOH groups using monomers on to the main back bone of the polymers would create new sites for cross links to be formed by metal oxides (ZnO, MgO etc.) or any other chemicals present in the formulation. Those new cross links formed in the system would enhance mechanical properties of the final product compared to C-S-C cross links formed by conventional sulphur vulcanization.
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Keywords
Science & Technology, Agriculture, Industrial Management, Entrepreneurial Agriculture