Carbon black affects the vulcanization properties of reclaimed rubber

Carbon black can be used as a reinforcing agent in the production of reclaimed rubber products to improve the mechanical strength of reclaimed rubber products such as tensile strength and elongation at break. It will also affect the vulcanization performance of reclaimed rubber during use; vulcanization as the last main process in the production process of reclaimed rubber product. Vulcanization effect has a great influence on the quality of the finished rubber products. Understanding how carbon black affects the vulcanization performance of reclaimed rubber is of great significance to improve the quality of reclaimed rubber products.
Theoretically, the amount of carbon black used in recycled rubber products continues to increase, and more carbon black gels (Carbon black gel is a combination of rubber. It is a part of rubber that cannot be dissolved by benzene when the rubber is mixed with carbon black, and can reflect the reinforcing effect of carbon black on the rubber compound.) will be formed during vulcanization. These rubber molecules whose activity is reduced due to binding will increase significantly, thereby reducing the reactivity between the reclaimed rubber and the vulcanizing agent, and delaying the vulcanization.

From another point of view, carbon black itself has a strong adsorption effect, it will adsorb part of the vulcanizing agent and accelerator in the rubber compound, and the part of the vulcanizing agent and accelerator adsorbed by the carbon black will increase as the amount of carbon black increases , resulting in a reduction in the amount of vulcanizing agent and accelerator in the cross-linking reaction of reclaimed rubber. The reduction in the concentration of vulcanizing agent and accelerator in the rubber compound directly leads to a decrease in the vulcanization rate of the rubber compound, and the scorch time and positive vulcanization time are extended.
Rubber fillers can be divided into soft fillers, semi-rigid fillers and rigid fillers according to rigidity. Carbon black is a typical rigid filler, which is combined with the rubber molecular chain through physical adsorption and chemical bonding. Within a certain range, carbon black particles and rubber molecules, as the junction of the chain increases, the hardness and modulus of the reclaimed rubber will increase and the torque will increase. Before using carbon black to produce rubber products, the scorch time, positive vulcanization time and vulcanization speed of the rubber are shorter. As the amount of carbon black continues to increase, the torque of the reclaimed rubber will continue to increase. The vulcanization time is prolonged. Therefore, when using reclaimed rubber, rubber product manufacturers must reasonably control the amount of carbon black. The comprehensive effect of carbon black on the vulcanization performance and mechanical properties of reclaimed rubber is continuously improved by adjusting the amount of carbon black.
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