The viscosity of raw rubber or mixed rubber can be used to characterize the forming performance of semi-finished products before vulcanization. It affects the production efficiency and quality of finished products. The appropriate viscosity is very important to the process of rubber mixing, calendering, pressing and vulcanization. High viscosity adhesive, poor fluidity, vulcanization filled model for a long time, easy to cause product appearance defects; And the glue with too small viscosity, the shear force generated by mixing and processing is not enough, it is difficult to make the coordination agent dispersed evenly, and it is easy to stick to the working parts of the equipment when calendering and pressing.

The viscosity of raw rubber mainly depends on the molecular weight and molecular weight distribution of rubber. The larger the molecular weight, the narrower the molecular weight distribution, the greater the viscosity of rubber. The viscosity of raw rubber can be adjusted by adjusting the molecular weight and molecular weight distribution of rubber. Plasticizing can reduce the viscosity of the compound. At present, most rubber has a wide range of Mooney viscosity, which can meet the performance requirements of different rubber materials. Raw rubber with certain Mooney viscosity can be selected in a wide range. Adding human plasticizer to raw rubber can improve plasticizing effect, reduce energy consumption and adjust the viscosity of rubber material. Such as adding plastic solution M or DM in plasticizing, can reduce the cat degree of natural rubber.

The properties and dosage of filler have great influence on the viscosity of adhesive. With the decrease of particle size of carbon black, the viscosity of rubber increases with the increase of structure and dosage. The smaller the particle size is, the greater the influence on the viscosity is. When the amount of carbon black in the rubber is increased, especially when it is more than 50, the effect of carbon black structure becomes significant. At high shear rate, the influence of carbon black type on adhesive viscosity decreases greatly. Increasing the dispersion degree of carbon black (prolonging the mixing time) can also reduce the viscosity of rubber.

Softening plasticizer is one of the main factors affecting the viscosity of the adhesive, which can significantly reduce the viscosity of the adhesive and improve the process performance of the adhesive.

Different softening plasticizers have different effects on the viscosity of various rubber compounds. To reduce viscosity rubber, natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, epdm rubber and butyl rubber non-polar rubber, add oil base class better soften plasticizer, and polarity of nitrile rubber, neoprene rubber, often adopt esters plasticizer, especially in cool phthalic acid and sebacic acid ester of esters plasticizer is better. In the requirement of flame retardant neoprene rubber rubber, liquid chlorinated paraffin and phosphate ester plasticizer are often used.

The use of petroleum softening plasticizer and ester plasticizer has little effect on the use of fluorine rubber, and these plasticizers are volatile at high temperature, so it is not suitable for use. Using low molecular weight fluororubber and chlorofluorocarbon liquid can reduce the viscosity of fluororubber by 33%~50%.

In isoprene rubber, styrene butadiene rubber, nitrile rubber, EPDM rubber and diethylene propylene rubber, the use of unsaturated acrylate oligomer as temporary plasticizer can reduce the viscosity of the rubber, and after vulcanization can form a spatial network structure, improve the hardness of vulcanized rubber. Using liquid rubber such as low molecular weight polybutadiene, liquid nitrile rubber, etc., can also achieve the purpose of reducing the viscosity of rubber.