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Heat shrink Principle of Heat Shrinkable Cable Accessories

2022-10-31
Physical states of polymers:

Heat Shrinkable Cable Accessories Organic compounds are actually hydrocarbons and their derivatives, from low molecular organic matter as raw materials, through polymerization reaction to produce long chain macromolecules, such as polyethylene, called polymers. Polymer molecules are usually in an irregular curling shape. Due to the length of the molecular chain and the different motion states of the chain and chain segments, the polymer has three different aggregation states. Under certain external force, the deformation of polymer increases with the increase of temperature.

Although the physical state of polymers has a certain stability, but because the general polymer is linear structure, under the action of heat and solvent is soluble and fusible state, can not be used as cable accessories materials. Therefore, the linear structure of the polymer must be changed to make it more stable.

Mode of crosslinking:

Heat Shrinkable Cable Accessories Cross-linking is the process of cross-linking linear polymers into bulk polymers, usually radiation cross-linking. Radiation cross-linking has the following advantages:

1. Because radiation cross-linking does not need to add crosslinking agent, there is no excess substance in the reaction system, and the product is pure.

2. The reaction speed has little dependence on temperature, and the quality of crosslinked products is stable through radiation dose control.

3. The polymer reaction can be initiated uniformly by radiation, and the shrinkage rate of radiation cross-linking is greater than that of chemical cross-linking. Therefore, radiation crosslinking is better than chemical crosslinking for heat shrinkable materials used in cable accessories.

Principle of thermal shrinkage of Heat Shrinkable Cable Accessories:

The cross-linked polymer is less elastic at room temperature, and exhibits a high elastic state when the temperature is higher than the glass transition temperature. At this time, an external force is applied to make it produce elastic deformation, and then it is cooled under the condition of keeping the type change. 

Because the temperature decreases the polymer molecular chain segment, the deformed shape is retained. As soon as the temperature is raised above the glass transition temperature again, the polymer chain suddenly relaxes, restoring elasticity. Under the action of elasticity, the material returns to its pre-deformation state, and this property is used to produce various heat-shrinkable accessory materials for cable terminals.
Heat Shrinkable Cable Accessories

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