Investigation of zinc oxide surface effect on polydienes vulcanization

Tests were carried out of complex vulcanization activators containing 30 wt. % zinc oxide based on P1T2 bentonite and zinc oxide with different specific surface areas. Vulcanization and elastic-strength properties of experimental and reference rubber compounds based on SKI-3 rubber and their vulcanizates were investigated. The experimental rubber compounds were obtained by replacing the traditional activator system (zinc oxide (5 parts by weight) and stearic acid (2 parts by weight)) with a complex vulcanization activator (5 parts by weight). It was found that the minimum torque in the experimental compounds was lower, which indicates good technological properties of the experimental rubber compounds. The optimum time and vulcanization rate were higher in the reference samples. Samples of complex vulcanization activators containing zinc oxide particles with a specific surface area from 5.2 to 18.1 m2/g were characterized by greater resistance to premature vulcanization. It has been established that the use of complex vulcanization activators allows to reduce the total time of manufacturing rubber compounds and vulcanizates. The elastic-strength indicators of the experimental rubbers in the presence of complex vulcanization activators were at the level of the reference ones. It is worth noting the best indicators of relative elongation at break for the experimental samples. It has been established that a complex vulcanization activator with a reduced content of zinc oxide and a specific surface area of zinc oxide particles from 4 to 7.5 m2/g mm provides the best set of physical and mechanical properties and can be recommended for practical use in rubber compounds, which will reduce the content of toxic zinc oxide for the environment and improve the technical and operational indicators of rubber products.