Meaning
Dialkyl peroxide compounds function as highly efficient free-radical initiators for the controlled degradation of polypropylene during extrusion compounding. This specific chemical agent, 2 5-dimethyl-2 5-di tert-butylperoxy hexane, decomposes at melt temperatures to generate tertiary alkoxy radicals. Compounders feed it to achieve a targeted melt flow rate.
Thermal Activation
Temperature-dependent decomposition of the initiator determines the rate of free radical generation. This organic peroxide requires a high activation energy to cleave its peroxide bonds. Extruder zones must be carefully calibrated to ensure complete decomposition before the melt exits the die.
Viscosity Reduction
Peroxide addition narrows the molecular weight distribution of the polymer and reduces its melt elasticity. The active radicals generated by 2 5-dimethyl-2 5-di tert-butylperoxy hexane extract tertiary hydrogen atoms from the polypropylene backbone, which initiates a fast beta-scission reaction that cleaves the long chains. Moulders rely on this viscosity reduction to fill multi-cavity moulds at lower temperatures.
This modification reduces injection pressure requirements and clamp forces, preventing flash and shortening cycle times for high-volume parts.
Volatile Release
Residual breakdown products can cause defects in the finished plastic part if they are not removed during extrusion. Gaseous byproducts from 2 5-dimethyl-2 5-di tert-butylperoxy hexane often cause odour issues or plate out on the polished mould surface. Intense vacuum degassing in the extruder removes these volatiles.
