PROCESSING OF INTRACTABLE POLYMERS USING HIGH-PRESSURE CARBON DIOXIDE

摘要

A modified extrusion system is used to process a variety of polymers (HDPE, LDPE, FEP, PTFE, s-PS) in the presence of high-pressure CO_2. The extruder's design includes a modified feed section that allows a given mass of polymer to interact with CO_2 prior to the extrusion process. This alternative design provides a new and easy route to melt process high melt viscosity polymers of commercial importance such as PTFE, FEP and s-PS. The inherent shear mixing and the presence of CO_2 allow for a specific control over the extrudate morphology. Some of the relevant parameters in the process are analyzed and related to the nucleation and plasticization effects brought about by the presence of CO_2.