As an important reinforcing agent for rubber, carbon black has driven the vigorous development of the rubber industry. It is mainly used to improve the wear resistance, tear strength, and tensile strength of vulcanized rubber. The following editor will introduce the reinforcement of carbon black in detail. mechanism and influencing factors.
There are many theories about the mechanism of carbon black reinforcement, such as weak bond and strong bond theory, shell model theory, Bueche's theory of finite elongation of carbon black particles and rubber chains, etc. With the continuous improvement of the concept, rubber The macromolecular sliding theory is a comprehensive and perfect theory. The core of this theory is that rubber macromolecules can move on the surface of carbon black. Due to the different surface activity and energy of carbon black, the rubber chains adsorbed on the surface of carbon black have different energies, and will slide and elongate under stress, which improves the rubber fracture. strength.
The particle size, structure, and surface activity of carbon black are called the three reinforcing elements of carbon black. The dispersion of carbon black is an important indicator to determine the reinforcing effect of rubber.
Among them, the particle size of carbon black has the greatest influence on the dispersion performance of rubber. Carbon black with small particle size has strong internal adsorption energy and poor wetting ability, so the dispersion speed in rubber is slow. , can indeed form a dense structure, so carbon black with fine particle size can improve the tear resistance and wear resistance of rubber.
The steric effect of branched chains of high-structure carbon black reduces the cohesive energy between particles, making it easier to be dispersed into rubber.
Affected by the raw materials and production process, the oxygen-containing groups on the surface of carbon black are more likely to form chemical cross-links with rubber macromolecules during the mixing process, which in turn affects the dispersion speed and diffusion direction of carbon black.