CO₂‐assisted polymer processing: A new alternative for intractable polymers

CO 2 ‐assisted polymer processing is proposed as an alternative route for intractable and high molecular weight polymers based on the plasticization effects of CO 2 and its direct effect on the melting behavior of semicrystalline polymers. A modified processing system was used to process a variety of polymers in the presence of high‐pressure CO 2 . The system includes an extruder that was modified to allow for high pressures created by the injection of CO 2 . The new design includes a modified feed section that allows a given mass of polymer to interact with CO 2 before and during the extrusion process. The inherent shear mixing and the presence of CO 2 allow for a specific control over the extrudate morphology. Results suggest that this alternative design provides a new and easy route to melt process high melt viscosity polymers of commercial importance, such as polytetrafluoroethylene (PTFE), fluorinated ethylene propylene copolymer (FEP), and syndiotactic polystyrene (s‐PS). The increased processability of these systems in CO 2 is related to the plasticization effect of CO 2 that was quantified through a depression in the glass‐transition temperature according to the Chow model.