Everyone knows that carbon black has reinforcing properties, but few people know what the reinforcing mechanism of carbon black is. This article introduces the reinforcing mechanism of carbon black through various aspects. , vulcanized rubber, natural rubber, what is the content of the reinforcement mechanism, this article will introduce to you.
Briefly describe the reinforcement mechanism of carbon black
The reinforcing effect of carbon black is mainly that the addition of carbon black changes the structure of the rubber and produces a C-phase structure. In the vulcanized rubber, if the carbon black is well dispersed and the surface of each carbon black particle forms a C-phase structure , Phase C plays a skeleton role to connect phase A and phase B. Forming an overall network of rubber macromolecules and fillers changes the structure of the vulcanized rubber, thus improving the physical and mechanical properties of the vulcanized rubber.
Reinforcement Mechanism of Carbon Black Surface Adsorption Layer Theory
According to the theory, carbon black and rubber form a microscopic heterogeneous structure, which belongs to a reinforcing mechanism of composite materials.
Nuclear magnetic resonance studies have confirmed that there is an adsorption layer composed of two kinds of rubber macromolecular structures on the surface of carbon black. The inner layer of about 0.5nm adjacent to the surface of carbon black is glassy; the rubber within 0.5-5.0nm away from the surface of carbon black is somewhat mobile and sub-glassy. This layer is called the outer layer. These two layers constitute the double-shell layer on the surface of carbon black, and the thickness of the double-shell layer is basically the above-mentioned range. The binding energy in the interface layer of this cool shell must continuously decrease from the inside to the outside, that is, the surface of carbon black is relatively large. The restraint of molecular mobility descends continuously, and finally reaches the free state where the rubber molecules are not restrained.
Reinforcement Mechanism of Carbon Black to Rubber
During mixing, the rubber molecules are broken into free radicals, which combine with the active centers on the surface of carbon black, or the oxygen-containing groups and free radicals on the surface of carbon black are cross-linked with rubber molecules to form chemical bonds during vulcanization.
Reinforcement Mechanism of Carbon Black Molecular Chain Sliding Theory
The core of this theory is that rubber macromolecules can slide on the surface of carbon black, thus explaining the reinforcement phenomenon. The activity on the surface of carbon black particles is not uniform, there are many strong 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 at least slightly strong chemical adsorption. Adsorbed rubber segments slide and elongate under stress.
Why do silica and carbon black have good reinforcing properties?
Jiululing Carbon Black Network believes that because rubber is an organic substance, it is mainly composed of C atoms and H atoms, and C in carbon black and Si in white carbon black belong to the same column in the periodic table of elements, and their nuclei There are 4 electrons on the outside, that is to say, they may be able to participate in the chemical reactions that take place inside during the rubber mixing and vulcanization process, and can form bonds with rubber molecules, thereby enhancing the bonding force between rubber molecules and achieving complementary strong effect.