The most important things that should have been considered in the Rubber industry is the formation of crosslinking between the main chain of the elastomeric compounds. There are several factors which could have effect on the density of the crosslinking through the vulcanization with sulfur, as instance we can mention on respect of the accelerator to the sulfur, temperature and time of vulcanization, kinds of preparative modes for incorporation of additives, kinds of catalyst (activator) that used. Rubber goods usually require a combination of properties that cannot be provided by one elastomer only and then two or more polymer components have to be mixed to meet specific requirements. In such cases, the additives normally employed in rubber formulations are unevenly distributed, depending on the affinity of each compound to each polymeric phase. Thus, the dispersion of each one of these ingredients in the different rubbers will influence the rate and degree of vulcanization and, in consequence, the performance of the final composite. For better heat conductivity and reinforcement in heavy-duty pneumatic tires, high loadings of zinc oxide are used, since heat-buildup is a critical problem at their higher operating speeds. But some adverse environmental effects of zinc exposure have been reported, which include decline in earthworm population densities, species diversity and the development of tolerant grass species. Hence, ZnO nanoparticles might help in reducing the level of ZnO in conventional formulations. We try to investigate The effects of particle size of zinc oxide (ZnO) on mechanical, thermal and morphological properties of compound. nanocomposites with varying concentration of ZnO were prepared by a melt mixing technique in a two roll mill. The effect of ZnO nanoparticles as cure activator was studied for the first time in NR/BR and NR/SBR blending compounds. In the compounds that consist of NR/BR blending without carbon black, observed special property in the high loading of nano zinc oxide (10phr) which have distinct properties in compare with 5phr and 15phr loading. The study on a rheograph confirmed that the ZnO nanoparticles gave a better state of cure and higher maximum torque with a marginal decrease in scorch time. The mechanical properties such as tensile strength ,modulus at 300% , elongation at break also showed an improvement for the vulcanizate cured with ZnO nanoparticles, as compared with the one containing rubber grade ZnO. ZnO nanoparticles were found to be more uniformly dispersed in the rubber matrix in comparison with the conventional rubber grade ZnO as evident from scanning electron microscopy/X-ray dot mapping analysis. The swelling ratio was found to decrease in the case of both NR/BR and NR/SBR blending compounds. From the current investigation it was found that by substitution of common grade zinc oxide with nano zinc oxide an increase in crosslinking density detected.
