Meaning
Chemical crosslinking of polymer insulation for high-voltage cables is initiated by an organic compound that generates free radicals upon thermal decomposition. In cable manufacturing, dicumyl peroxide crosslinks low-density polyethylene, transforming it into crosslinked polyethylene with superior thermal and mechanical properties. The reaction raises the maximum continuous operating temperature of the cable insulation.
Curing Action
Thermal activation of the additive occurs during the extrusion process at elevated temperatures. Once activated, dicumyl peroxide generates alkoxy radicals that abstract hydrogen atoms from the polyethylene chains, creating reactive sites that bond to form a robust three-dimensional network. This crosslinked structure resists deformation under high electrical and mechanical stress.
Byproduct Management
Volatile compounds remaining after the curing process must be removed to prevent electrical treeing under high-voltage conditions. The breakdown of dicumyl peroxide generates acetophenone and cumyl alcohol, which accumulate at material interfaces. Manufacturers run a degassing step in a heated vault to drive off these byproducts before the protective jacket is applied.
Quality Testing
Verification of the degree of crosslinking is performed using solvent extraction tests to measure gel content. A high gel fraction confirms that the reaction achieved the density required for long-term thermal stability. This test represents a critical release criterion before shipment.
