What are the Crosslinking Methods for Chlorinated Polyethylene (CPE)?

1. Peroxide Crosslinking
Method:

Uses organic peroxides (e.g., dicumyl peroxide) as crosslinking agents.

Upon heating, peroxides decompose to form free radicals that initiate crosslinking.

Mechanism:

Free radicals generated from peroxide decomposition react with polymer chains, forming crosslinks.

Advantages:

High chemical resistance.

Good mechanical properties.

Applications:

Cable insulation.

Automotive parts.

Seals and gaskets.

2. Silane Crosslinking
Method:

Involves grafting silane compounds (e.g., vinyltrimethoxysilane) onto the polymer chain.

The grafted polymer is then exposed to moisture (typically in the presence of a catalyst) to form crosslinks through hydrolysis and condensation reactions.

Mechanism:

Silane groups react with hydroxyl groups, forming siloxane crosslinks (Si-O-Si).

Advantages:

Enhanced adhesion.

Improved durability.

Suitable for ambient curing.

Applications:

Coatings.

Adhesives.

Cable insulation.

3. Radiation Crosslinking
Method:

Uses high-energy radiation (e.g., gamma rays or electron beams) to generate free radicals within the polymer.

Mechanism:

Free radicals formed by radiation induce crosslinking between polymer chains.

Advantages:

High thermal stability.

Improved mechanical properties.

No need for chemical additives.

Applications:

Industrial hoses.

Roofing membranes.

Medical devices.

4. Sulfur Crosslinking
Method:

Involves the use of sulfur or sulfur compounds as crosslinking agents, typically in the presence of accelerators and activators.

Mechanism:

Sulfur atoms form bridges (crosslinks) between polymer chains, enhancing durability.

Advantages:

Improved tensile strength and elasticity.

Enhanced resistance to abrasion and wear.

Applications:

Automotive hoses.

Conveyor belts.

Rubber linings.

5. Azo Compound Crosslinking
Method:

Uses azo compounds (e.g., azobisisobutyronitrile) as crosslinking agents.

Upon heating, azo compounds decompose to generate free radicals.

Mechanism:

Free radicals from azo decomposition initiate crosslinking.

Advantages:

Effective at low temperatures.

Improved resistance to heat aging.

Applications:

Heat-resistant cables.

Industrial seals.

High-performance rubbers.