The Action Mechanism of Carbon Black in Rubber
Carbon black is a micron sized amorphous carbon particle obtained from incomplete combustion or pyrolysis of carbon containing substances. It is one of the most important fillers in the rubber industry and is widely used in rubber products such as tires, hoses, and tapes. Carbon black can not only improve the mechanical properties, wear resistance, aging resistance, and conductivity of rubber, but also reduce the cost and weight of rubber. So, how does carbon black play these roles in rubber? This article will introduce the mechanism of carbon black in rubber from the following aspects:
The reinforcing effect of carbon black
The strengthening effect of carbon black refers to the physical properties of rubber, such as strength, hardness, modulus, and wear resistance, which can be improved by carbon black, enabling rubber to have better load-bearing capacity and service life. The enhancement effect of carbon black mainly depends on the following factors:
Specific surface area of carbon black:
Specific surface area refers to the surface area of carbon black per unit mass or volume, which reflects the size and morphology of carbon black particles. Generally speaking, the larger the specific surface area, the smaller the carbon black particles, and the larger the contact area with rubber molecules, thereby increasing the friction and bonding force between rubber and carbon black, and improving the reinforcement effect of rubber.
The structure of carbon black:
Structure refers to the degree to which carbon black particles aggregate and form aggregates, reflecting the voids and pores between carbon black particles. Generally speaking, the higher the structure, the more voids and pores between carbon black particles, and the stronger the entanglement between rubber molecules, thereby increasing the friction and adhesion between rubber and carbon black, and improving the reinforcement effect of rubber.
Dispersion of carbon black:
Dispersion refers to the degree to which carbon black is uniformly distributed in the rubber matrix, which reflects the compatibility and flowability of carbon black with rubber during the mixing process. Generally speaking, the better the dispersibility, the finer, more uniform, and more stable dispersed phases formed by carbon black in rubber, allowing each carbon black particle to fully exert its reinforcing effect and improve the overall performance of the rubber.
The Conductive Effect of Carbon Black
The conductivity of carbon black refers to its ability to improve the conductivity of rubber, enabling it to have special functions such as anti-static, anti-interference, and corrosion resistance. The conductivity of carbon black mainly depends on the following factors:
Carbon black content:
Content refers to the mass or volume of carbon black contained in rubber per unit mass or volume, which reflects the proportion of carbon black in rubber. Generally speaking, the higher the content, the higher the concentration of carbon black in rubber, which increases the contact and connection between carbon black particles, forming a conductive network and improving the conductivity of rubber.
Resistivity of carbon black:
Resistivity refers to the resistance value of carbon black per unit length and cross-sectional area, which reflects the conductivity of carbon black particles themselves. Generally speaking, the lower the resistivity, the better the conductivity of carbon black particles themselves, thereby reducing the resistance between carbon black particles and improving the conductivity of rubber.
The form of carbon black:
Morphology refers to the shape and surface characteristics of carbon black particles, which reflect the contact mode and connection strength between carbon black particles. Generally speaking, the more regular the morphology, the larger the contact area between carbon black particles, thereby increasing the contact and connection between carbon black particles and improving the conductivity of rubber.
Anti aging effect of carbon black
The anti-aging effect of carbon black means that carbon black can delay the aging phenomenon caused by light, heat, oxygen, ozone and other factors during the use of rubber, so as to maintain good physical properties and appearance. The anti-aging effect of carbon black mainly depends on the following factors:
Absorbance of carbon black:
Absorbance refers to the ability of carbon black to absorb light, which reflects the protective effect of carbon black on light aging. Generally speaking, the stronger the light absorption, the stronger the absorption ability of carbon black to light, thereby reducing the breakage and cross-linking of rubber molecular chains caused by light, and improving the light aging resistance of rubber.
Oxygen absorption of carbon black:
Oxygen absorption refers to the ability of carbon black to absorb oxygen and ozone, which reflects the protective effect of carbon black on oxygen aging and ozone aging. Generally speaking, the stronger the oxygen absorption, the stronger the absorption capacity of carbon black for oxygen and ozone, thereby reducing the breakage and cross-linking of rubber molecular chains caused by oxygen and ozone, and improving the anti oxygen aging and ozone aging effects of rubber.
Carbon black surface activity:
Surface activity refers to the polar or functional groups contained on the surface of carbon black, which reflects the interaction between carbon black and rubber molecules. Generally speaking, the higher the surface activity, the more polar or functional groups the carbon black surface contains, thereby increasing the chemical or physical bonds between carbon black and rubber molecules, improving the interfacial adhesion between rubber and carbon black, reducing the migration or fracture of rubber molecular chains under stress, and improving the dynamic aging resistance of rubber.
