Rubber carbon black reinforcement principle
Through the three stages of rubber molecular state change, the preparation process of carbon black filled rubber is completed. In the first stage, during the mixing process, the rubber molecules are very firmly adsorbed on the surface of the carbon black particles, even after the carbon black filler is vulcanized, it still maintains the bonded rubber and the non-crosslinked state of the bonded rubber; in the second stage, with With the increase of carbon black content, adjacent non-crosslinked bonded rubbers are bonded to each other to form a continuous network; in the third stage, under stretching conditions, the rubber molecules in the bonded rubber are stretched and oriented, and finally, become into a molecular chain bundle stretched to the limit state.
Three elements of carbon black to reinforce rubber
The three elements of carbon black reinforcement are particle size, structure and surface activity of carbon black.
The earliest use of carbon black to reinforce rubber
Carbon black was widely used as a reinforcing agent for rubber in 1920.
Two Reinforcing Effects of Carbon Black Reinforced Rubber
The mechanism of carbon black reinforcement can be divided into physical adsorption and chemical combination. Physical adsorption can be explained as ①, the rubber molecular chain is adsorbed on the surface of the filler particles, resulting in the formation of a two-dimensional state of orientation arrangement, which improves the mechanical strength ②, due to the adsorption under the action of stress, the chain segments adsorbed on the surface of carbon black particles can occur The sliding phenomenon promotes the redistribution of stress and improves the breaking strength of rubber.
Mechanism of rubber carbon black reinforcing agent
For nearly half a century, people have conducted extensive discussions on the mechanism of carbon black reinforcement and put forward a variety of reinforcement theories. Among them are: volume effect, weak bond and strong bond theory, Bueche's carbon black particle and rubber chain finite elongation theory, shell model theory and rubber macromolecular chain sliding theory.
Sliding theory of macromolecular chains in carbon black reinforced rubber
This is a relatively new and comprehensive carbon black reinforcement theory. The core of this theory is that rubber macromolecules can slide on the surface of carbon black, which explains the reinforcement phenomenon. The surface activity of carbon black particles is not uniform, there are a few active points and a series of adsorption points with different energies. The rubber chains adsorbed on the carbon black surface can have various binding energies, ranging from mostly weak van der Waals adsorption to a small amount of strong chemical adsorption. Adsorbed rubber segments slide and elongate under stress.