The Significance of Indicators of Silica in Application for Rubber
Specific Surface Area
The reinforcing effect of specific surface area PPT silica mainly depends on its specific surface area, which generally increases with the specific surface area. The strength indexes of rubber products increase, but the resilience decreases, tear strength decreases, and wear-resistant. It is difficult to disperse when mixing, with high heat generation, high Mooney viscosity and easy to scorch. Therefore, different formulations and different uses require different specific surface area. Similarly, the effect of specific surface area on the physical and mechanical properties of vulcanized rubber is not consistent.
Oil Absorption
The oil absorption value reflects the structure degree, the oil absorption value is large, the structure degree is small, the elongation of vulcanizate is generally larger, the tensile strength and hardness are bigger, especially the wear resistance is smaller, but the elongation rate is lower.
Reduction of Calcination
The reduction of calcination at 900 C reflects the surface hydroxyl group. When the surface hydroxyl group is too much, it is easy to cause the structure of rubber composites and make them brittle. The processing property is affected, and vulcanizate is easy to fall off, and the surface hydroxyl group has strong adsorption effect on vulcanization accelerator, prolonging vulcanization time.
Heating Reduction
Heating reduction at 4 and 105 C reflects the amount of free water in the voids of particles. When too little, it becomes difficult to refine rubber with high degree of structure. If the heating reduction is zero, silica is useless. Generally, it is appropriate to control it at about 6%.
The PH value
The PH value is about 7, the PH value increases (the acidity decreases), and the vulcanization speed of the compound accelerates.
Soluble Salt Content
The less the soluble salt content, the better, but if we want to reduce the soluble salt content, the production cost will be greatly increased.