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

• Published in: Journal of applied polymer science Vol. 93; no. 4; pp. 1501 - 1511
• Main Authors: Garcia-Leiner, Manuel, Lesser, Alan J.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.08.2004; Wiley
• Subjects: Applied sciences; Exact sciences and technology; extrusion; fluoropolymers; Physicochemistry of polymers; Polymer industry, paints, wood; processing; supercritical carbon dioxide; syndiotactic polystyrene; Technology of polymers; syndiotactic polystyrene; Propylene copolymer; Fluorine containing copolymer; Molten state; Tetrafluoroethylene polymer; Processability; Semicrystalline polymer; supercritical carbon dioxide; Morphology; extrusion; Ethylene copolymer; Supercritical solvent; processing; fluoropolymers; Plasticization
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.20619

CO2‐assisted polymer processing is proposed as an alternative route for intractable and high molecular weight polymers based on the plasticization effects of CO2 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 CO2. The system includes an extruder that was modified to allow for high pressures created by the injection of CO2. The new design includes a modified feed section that allows a given mass of polymer to interact with CO2 before and during the extrusion process. The inherent shear mixing and the presence of CO2 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 CO2 is related to the plasticization effect of CO2 that was quantified through a depression in the glass‐transition temperature according to the Chow model. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1501–1511, 2004