What is the role of each index of silica in the application

Introduction: The main component of white carbon black is SiO2, which is named because it is white, and its main physical properties and uses are similar to carbon black.


According to different production methods, white carbon black can be divided into precipitated white carbon black (precipitated hydrated silica), gel method white carbon black and fumed white carbon black (fumed silica). The production methods of the three products are different. The nature and use are also very different.


The products introduced below are produced by the sulfuric acid precipitation method, that is, the precipitation method white carbon black. The following white carbon blacks are all precipitation method white carbon blacks.


 The role of each index of white carbon black in application


1. Specific surface area


The reinforcing effect of white carbon black mainly depends on its specific surface. Generally, with the increase of specific surface area, the various strength indexes of rubber products increase, but the resilience decreases, the tear strength decreases, and it is not abrasion resistant. Difficulty in dispersion during refining, high heat generation, high Mooney viscosity of the rubber, and easy scorch. Therefore, different formulations and different uses require different specific surface areas. The specific surface area has different effects on the physical and mechanical properties of vulcanized rubber.


2. Oil absorption value


The oil absorption value reflects the degree of structure, the oil absorption value is large, the structure degree is small, the elongation strength of the vulcanizate is generally large, the tensile strength and hardness are large, especially the wear resistance is small, but the elongation is low .


3. Loss on ignition at 900℃


The performance is that when there are too many surface hydroxyl groups, it is easy to cause the structure of the rubber composite material and make the material brittle. It affects the processing performance, and the vulcanized rubber is easy to fall off, and the surface hydroxyl has a strong adsorption effect on the vulcanization accelerator, which prolongs the vulcanization time.


4. Heating loss at 105℃


It reflects the amount of free water in the particle voids. When it is too small, the structure of the rubber compound will be high and it will be difficult to mix. If the heating loss is zero, the white carbon black is useless. Generally, it is more appropriate to control it at about 6%.


5. PH value


Generally around 7, the PH value increases (the acidity decreases), and the rubber vulcanization speed increases. ,


6. Soluble salt


The less the better, but the less the higher the cost.