Polymer plasticization using supercritical carbon dioxide

Abstract

The plasticizing effect of supercritical CO2 (scCO2) during the extrusion of polymers was investigated. A modified extrusion system was used to demonstrate the viscosity‐reducing effect of scCO2 together with a capability to produce foam‐free extrudate with selected polymers, including poly(vinyl chloride). Samples of extrudate and materials prepared off‐line by using a pressure vessel were characterized by thermal, mechanical, and X‐ray techniques. After gas diffusion from the polymer, there was no long‐term effect on polymer structure and properties. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.

Fabrication of highly expanded thermoplastic polyurethane foams using microcellular injection molding and gas‐laden pellets

“…This is because of the plasticizing effect of the CO 2 injected during extrusion. It is well known that CO 2 is able to serve as an effective plasticizer during melt processing [30][31][32][33]. Once CO 2 is injected and blended into the melt, the viscosity, shear stress, and shear heating of the melt flow can be significantly reduced during melt processing, and thus the molecular weight and melt strength can be better preserved after processing.…”

Effect of pressurized CO2 and N2 on the rheology of PLA

“…In general, it has been shown that CO 2 acts as a molecular lubricant when it is absorbed into a polymer, increasing segmental and chain mobility and also increasing interchain distance [29]. Due to this local increase in mobility, the glass transition temperature is dramatically reduced and the polymer flows more easily.…”