“Radiation Vulcanization of Polymeric Blends Based on Ethylene Propylene Diene Monomer Rubber/ Waste Materials in Presence of Different Additives"

Abstract

In this investigation, the mechanical blending technique was applied for preparation of elastomeric blend of ethylene propylene diene monomer rubber (EPDM)and nitrile butadiene rubber (NBR) having a fixed ratio of (50/50) by weight. The prepared blend of EPDM/NBR (50/50) was used as a rubber matrix to be loaded with waste materials, namely rice husk (RH) as a natural waste filler and then with ground tire rubber (GTR) as an artificial one. The degree of loading varied from 5phr to 20 phr. Ionizing radiation, namely ,gamma rays were applied for inducing vulcanization of prepared and loaded rubber blends, in the range from 5 kGy to 250 kGy. Different properties of prepared composites were followed up as a function of degree of loading with the waste material and dose of irradiation. The mechanical properties, namely tensile strength and elongation at break percent of the composites slightly decreased as the filler loading increased over the whole range of irradiation .Tensile modulus and hardness, on the other hand, showed an opposite trend, i.e. the increased. Other properties, namely physical, thermal and morphological confirmed the mechanical ones. Obtained results were affiliated with lack of interface adhesion between the waste materials and the rubber matrix elastomers. The lack of interface adhesion was improved by filling the composite with a limited content, up to 7 phr, of the compatibilizer, namely, maleic anhydride (MAH). Measurements of different properties were carried out for composite loaded with 10 phr of waste material. It has been found that the tensile properties were significantly improved with addition of the compatibilizing agent. Further and significant improvement was attained in properties of prepared later composite by its loading with 40 phr of either HAF-carbon black or Hisil as reinforcing fillers that participates in chemical as well as physical bonding. Similarly and lastly 8 phr of N, N- methylene diacrylamide (MDA) were loaded as an enhancing polyfunctional monomer, i.e. co-agent Properties obtained showed further improvement due to its participation in gel formation.