Melt Shear History and Contaminant Catalyzed Scission in Post Consumer Polyolefin Silo Blends
Deactivate metal catalysts and neutralize acid traces with targeted additives to stabilize viscosity drift and optimize landed cost per good recycled part.
Peroxide Reactive Compounding
Meaning
Chemical modification processes use organic peroxides during extrusion to alter the molecular weight and rheological behavior of polymer resins. Through peroxide reactive compounding, compounders can tailor the melt flow index of polypropylene or the degree of crosslinking in polyethylene. This process allows for the production of specialized grades of resin from a single base material.
It is a cost-effective method for modifying polymer properties on a large scale.
Polypropylene Cracking
In polypropylene processing, organic peroxides break down high molecular weight chains. During peroxide reactive compounding, this visbreaking reaction increases the melt flow rate.
Polyethylene Crosslinking
Polyethylene resins can be modified to improve their thermal and mechanical performance by creating chemical bonds between chains. In this application, peroxide reactive compounding generates free radicals that link the polymer molecules together. This crosslinking reaction increases the material’s resistance to environmental stress cracking and elevated temperatures.
It is commonly used in the manufacture of high-durability pipes and cable insulation. This chemical change requires careful dosing of the peroxide to prevent premature gelation in the extruder.
Extruder Control
The success of reactive compounding depends on precise control over temperature and residence time. When conducting peroxide reactive compounding, the extruder barrel temperatures must be set to ensure complete decomposition of the peroxide. If the temperature is too low, unreacted peroxide remains in the polymer and causes downstream defects.
If it is too high, the reaction occurs too early and leads to process instability. This balance is maintained by using advanced liquid-injection dosing pumps and screw profiles.