Evaluation of Performance of Natural Rubber Composites with Different Sizes of Waste Tyre Rubber (WTR) and Precipitated Silica on C-M-M

Effect of different sizes of waste tyre rubber on natural rubber-silica compounds was studied with a view to assess the mechanical performance of rubber articles. The WTR was intended as a filler material to blend with natural rubber and form a novel rubber composite material. In this work, WTR particles were prepared in three different sizes (150-250, 450-600, and 1200-1500 mu m) using pulverization method. Then, the particles were blended with natural rubber and silica compounds, and the blend was synthesized by two-roll mill and hydraulic press. The composite material samples ranged from 0 to 40 phr of WTR loading in each size, and silica loading was fixed at 20 phr. The various proportions of samples in all sizes were characterized in respect of their curing characteristics, mechanical properties, and morphology test (C-M-M). Curing results showed that scorch time and optimum cure time significantly decreased in all particle sizes. Minimum torque increased with the addition of WTR, and maximum torque was vice versa. The results of the mechanical properties showed that the particle size 150-250 mu m affected better enhancement in the mechanical properties than the other particle sizes. However, tensile strength and elongation at break decreased while WTR loading increased. Hardness increased up to 30 phr and tear strength increased up to 20 phr of WTR in rubber compounds for small particle sizes which were comparatively higher than other sizes. The morphology of the samples examined by scanning electron microscopy revealed that particles of small size got uniform dispersion and lesser torn surfaces. The results indicated increased life duration of rubber articles for potential applications.