1. Aggregation Properties of Rubber The state in which rubber molecules are brought together is called the aggregation state. Aggregation states can be divided into three states: solid, liquid, and gas. Rubber has liquid properties because the molecular segments of rubber can move relatively freely like low molecular liquids. Rubber has the property of being solid, because the molecular chain cannot be relatively displaced from the viewpoint of the entire macromolecular chain, and can maintain a certain shape and a large strength. Rubber also has the property of gas, such as the modulus of elasticity increases with the increase of temperature, and heat is generated when stretching, as if the gas is compressed, the heat is converted by energy.
2. The viscoelastic rubber of rubber has good elasticity. In addition, it also has certain characteristics of obvious viscous liquid. It is mainly manifested in the fact that after the rubber is stressed, its deformation develops linearly with time like the viscous liquid. . Therefore, rubber is considered to be a viscoelastic material, resulting in a series of viscoelastic phenomena such as creep, stress relaxation, and internal friction.
3. Rheological properties of rubber Although rubber has high elasticity, its molding process, such as mastication, mixing, extrusion or calendering, needs to be deformed under flowing conditions. Therefore, the molding process necessarily involves the fluidity of rubber. Viscosity is an important parameter to characterize liquid fluidity. The viscosity of rubber is different from that of plastic. Plastic can greatly reduce the viscosity of the melt by increasing the temperature. The viscosity of rubber is little affected by temperature, which depends mainly on the relative molecular mass. Reducing the relative molecular mass can reduce the viscosity and elasticity, which will be beneficial to the molding process of rubber.