Rubber Carbon Black is the main reinforcing agent in the rubber industry. For decades, people have extensively discussed the mechanism of carbon black reinforcement, and summarized the principle of carbon black as rubber reinforcement.
In this paper, Beilum Carbon Chemical (www.beilum .com) will introduce to you what is the reinforcing principle of carbon black in rubber ?
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, as the content of carbon black increases, adjacent non-crosslinked rubbers adhere to each other to form a continuous network;
In the third stage, under stretching conditions, the rubber molecules in the combined rubber are stretched and oriented, and finally, become molecular chain bundles 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.
Two Reinforcing Effects of Rubber 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, forming 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 slide, which 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, finite elongation theory of carbon black particles and rubber chain, 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.