Main structure of rubber
Linear structure: the general structure of unvulcanized rubber. Due to the large molecular weight, the macromolecular chain is in the form of a random coil curve without external force. When the external force acts, the removal force is removed, the entanglement of the coil changes, and the molecular chain rebounds, resulting in a strong tendency to recover. This is the origin of rubber high elasticity.
Branched structure: aggregation of branches of rubber macromolecular chains to form a gel. Gels are detrimental to the performance and processing of rubber. In the rubber mixing, various compounding agents often cannot enter the gel area, forming a partial blank, which cannot form reinforcing and cross-linking, and become a weak part of the product.
Crosslinked structure: Linear molecules are connected to each other by bridging of some atoms or groups of atoms to form a three-dimensional network structure. This structure continues to increase as the vulcanization process progresses. Thus, the free mobility of the segments is reduced, the plasticity and elongation are lowered, the strength, elasticity and hardness are increased, and the compression set and the degree of swelling are lowered.