First, the reinforcing effect of carbon black on rubber depends on the properties of carbon black, such as particle size, shape of the focusing body and surface chemistry of the particles. It does not depend solely on a certain nature of carbon black, but the result of the combined effects of various basic properties of carbon black. Carbon black particle size is an important factor in the reinforcement of carbon black. The finer the carbon black, the better the reinforcing performance. The industry has determined that the high wear-resistant furnace black HAF is standard, the specific surface area is 80 square meters / gram, the relative reinforcement is 100, other carbon black is higher or lower than 100, experiments show that when the specific surface area is greater than 50 square meters, Only showed better reinforcement. When the carbon black particle size is below 50 μm, that is, between the cross-linking points of the vulcanized rubber and the length of the segment is of the same order of magnitude, it can show better reinforcement and fruit. The specific surface area of the carbon black particles is 150-200 square meters per gram, and the particle size is much smaller than the length of the segments between the cross-linking points. At this time, the rubber molecular segments can be fully adsorbed on the surface of the carbon black particles, and the two are firmly bonded to each other. together. The specific surface area of carbon black has a significant effect on the amount of carbon black gel produced by rubber. The specific surface area is large, and the amount of gel formation is more, and the amount of gel formation is an important indicator of the reinforcing effect of carbon black. Since the gel of carbon black is a combination of rubber and carbon black, it contributes to the formation of a reinforcing structure of carbon black. The particle size of carbon black has a significant effect on the physical and mechanical properties of vulcanized rubber. For example, the influence of particle size on the tensile strength of natural and styrene-butadiene vulcanizates, the tensile strength increases with the decrease of particle size, and the tensile strength also follows. The particle size decreases and decreases, but becomes a certain value to a certain extent, and the elongation decreases as the particle size decreases, and decreases to a certain extent. The carbon black particle size also has a significant effect on the wear resistance, resilience, hardness and permanent compression deformation of the vulcanizate. Experiments show that the smaller the carbon black particle size, the better the wear resistance of the vulcanizate, and the carbon black The variety has little to do with. An hourly particle size increases the heat build-up and hysteresis loss of the vulcanizate and exhibits less resilience. The particle size is increased and the tear strength is lowered. The carbon black particle size also has a significant effect on the hardness of the vulcanizate, and the hardness increases as the specific surface area increases. However, the hardness does not change after increasing to a certain value. The properties of tensile strength, elongation, hardness, tear strength, etc., all show significant turning points as a function of specific surface area.
Second, the influence of the degree of carbon black structure on the reinforcing property, the degree of carbon black structure has an important influence on the reinforcing property of vulcanized rubber, and has a significant correlation with the tensile strength of vulcanized rubber. Carbon black with different structural degrees can obtain the same reinforcing effect of vulcanizate. The amount of carbon black required is different. If the carbon black structure is high, the amount can be relatively reduced. This is mainly the reinforcing effect of carbon black and the particles of carbon black. There is a direct relationship between the containment volumes of aggregates. The structural degree has the most prominent influence on the tensile strength. Under the same particle size, the higher the structural degree, the greater the tensile strength. Increasing the structural degree of carbon black can lower the elongation, increase the tensile strength and hardness, and in particular, improve the wear resistance.
The degree of carbon black structure also has an effect on the dynamic properties of the vulcanizate. Under the same fatigue conditions, the high structure carbon black can improve the hysteresis loss and heat build-up of the vulcanizate. However, under the same deformation load, due to the large tensile strength, the deformation ability is small, and the hysteresis loss and heat generation are reduced.
The degree of carbon black structure has different effects on the reinforcing properties of crystalline rubber or amorphous rubber. High structural carbon black has a much greater effect on the tensile strength or tear strength of amorphous rubber than crystalline rubber. On the contrary, the low structural carbon black has higher tensile strength or tear strength and reinforcing effect on the crystalline rubber than the amorphous rubber.
The degree of carbon black structure has a great influence on the electrical conductivity of vulcanized rubber. The higher the structure, the stronger the electrical conductivity. For example, acetylene black has a high degree of structure, giving the vulcanized rubber maximum electrical conductivity.