Linear structure: the general structure of unvulcanized rubber. Due to its large molecular weight, it is in the shape of fine ball without external force. When the external force is removed, the entanglement of the fine particles changes, and the molecular chain rebounds, resulting in a strong recovery tendency, which is the origin of rubber’s high elasticity.
Branch chain structure: aggregation of branch chains of rubber macromolecules to form gel. Gel is unfavorable to the properties and processing of rubber. When mixing rubber, various compounding agents often cannot enter the gel area, forming a local blank, which can not be reinforced and cross-linked, becoming the weak part of the product.
Cross linked structure: linear molecules are connected with each other by bridging some atoms or atomic clusters to form a three-dimensional network structure. With the process of vulcanization, this structure is continuously strengthened. In this way, the free mobility of the chain segment decreases, the plasticity and elongation decrease, the strength, elasticity and hardness increase, and the compression permanent deformation and swelling decrease.
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