Plasticity of rubber

The ability of rubber to deform under external forces and maintain its deformation even after the external forces are eliminated is called plasticity. The process of increasing the plasticity of rubber is called plasticization. Rubber has plasticity in order to mix evenly with various additives during mixing; Easy to penetrate into textile fabrics during rolling processing; It has good fluidity during extrusion and injection. In addition, molding can also make the properties of rubber uniform, making it easy to control the production process. However, transition molding can reduce the strength, elasticity, wear resistance and other properties of vulcanized rubber, so the molding operation needs to be strictly controlled.
The plasticity requirement of raw rubber is appropriate, and either too large or too small can have adverse effects. Excessive plasticity of raw rubber can reduce the physical and mechanical properties of vulcanized rubber, affecting the usability of the product. If the plasticity of raw rubber is too low, it will cause difficulties in processing and make it difficult for the rubber material to be mixed evenly; Rolling, the surface of the semi-finished product is not smooth when pressing out; Large shrinkage penalty makes it difficult to grasp the size of semi-finished products; During rolling, it is difficult for the adhesive tape to rub into the fabric, causing peeling of the hanging adhesive cord fabric and greatly reducing the adhesion between the material layers. If the plasticity is uneven, it can also cause inconsistencies in the technological and physical mechanical properties of the adhesive.
Therefore, the rubber processing technology has certain requirements for the plasticity of raw rubber. Generally speaking, adhesives used for coating, dipping, scraping, and manufacturing sponge adhesives require high plasticity; Rubber materials and molding materials that require high physical and mechanical properties and good stiffness of semi-finished products should have low plasticity; The plasticity of the extruded adhesive is between the two.