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Application of scrap rubber and worn out tires in natural rubber compounds has been studied. The scrap rubber can, however, be recycled and compounded with natural rubber and thus can be generated as a rubber composite. In this work, recycled rubber particles (RRP) were prepared using pulverization process. Then, RRP was blended with natural rubber and silica compounds, and it was synthesized by two-roll mill and hydraulic press at specified operating conditions. The samples ranging from 0 to 40 phr of RRP loaded with silica were used as constant filler. The mechanical properties and morphological analysis were carried out. The results showed that tensile strength and elongation at break gradually decreased with increasing RRP loading in natural rubber and silica compounds. Tensile modulus went down at 10 phr of RRP and then showed an increasing trend. Hardness increased up to 30 phr of RRP and tear strength increased up to 20 phr of RRP. A comparative study was also carried out with virgin natural rubber vulcanizates. The incorporation of RRP and silica up to 20 phr in natural rubber did not lower the performance of rubber articles. Morphological studies revealed that better filler dispersion, interfacial adhesion, and cross link density could increase the tensile and tear strengths.

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Friction stir welding produces better joint strength comparing with other conventional fusion welding techniques as the complete metal joining operation is executed in solid state itself. Even though the quality of weld is comparatively good, this joining technique has its own disadvantages. Improper material flow along the weld line may result in weld defects. Usage of polygonal pin geometry in tool pin rather than using conventional cylindrical pin geometry enhances flow of plasticized metal under the tool shoulder in the stir zone. Major problem associated with polygonal shaped tool pin is poor tool life. Yield strength of material under the tool shoulder creates opposing force for the movement of tool pin, which is submerged inside the workpiece for the entire joining process. Uneven stress distribution along the outer surface of the polygonal tool pin shape leads to premature tool failure. As the strength of material is a temperature dependent property, the heat input during the process has to be optimised with respect to the geometrical shape of the tool pin to improve tool life without compromising the weld quality a lot. In this paper, the variation in thermal field based on the geometrical shape of the tool pin was analysed using MATLAB based on the moving coordinate system. Rosenthal equation was used to estimate variation the peak temperature and temperature distribution with respect to pin shape in the view of optimising thermal environment towards better weld quality.