RECYCLING OF RUBBER CHIPS INTO COMPOSITE ELASTOMERS

Abstract

This research work focused on standardizing and optimizing the current localmethods of recycling tread tyre chips that are generated as waste in re-treadingindustries. Existing factory processing methods, such as used in wheelbarrowtyre and car mat production were analysed and their shortcomings highlighted.These shortcomings were used as improvement areas in the research. Physicalproperties such as size and weight of various samples of scrap chips from differentre-treading companies were compared and a grading code generated usingmeshes. The graded chips were surface treated with potassium permanganate togenerate hydroxyl groups on the rubber surface, in order to facilitate a reactionwith virgin natural rubber (NR). Various chips/NR volume ratios were prepared,processed and cured using conventional industrial procedures. The mechanicalproperties of the samples, such as tensile strength, hardness, elongation at break(%), resilience (%) and abrasion resistance were tested and compared with thoseof specimens prepared using existing manufacturing methods. Blend cost analysisand mechanical properties optimization are among the areas that were givenextra emphasis due to their importance in this research. New formulations weregenerated to produce superior products that will create a new market for thisplastic pollutant thereby reversing the effect it has on the environment.The results showed that tread particle size form the fundamental basis forthe control of most mechanical properties(toughness, elongation and abrasion)of recycled rubber vulcanizates. For a natural rubber based formulation suchas used in wheelbarrow tyre manufacture, the tread buffings were found to begood extenders of natural rubber while still imparting moderate improvementson the mechanical properties. Also, the buffings were found to improve thetensile properties of virgin NR vulcanizates through blend aging