Prediction of the viscosity reduction due to dissolved CO 2 of and an elementary approach in the supercritical CO 2 assisted continuous particle production of a polyester resin

• Published in: Powder technology Vol. 170; no. 3; pp. 143 - 152
• Main Authors: Nalawade, Sameer P., Nieborg, Vincent H.J., Picchioni, Francesco, Janssen, L.P.B.M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2006
• Subjects: Extruder; Free volume theory; Nozzle; Static mixer; Supercritical CO 2; Viscosity; Viscosity; Extruder; Supercritical CO 2; Free volume theory; Nozzle; Static mixer
• ISSN: 0032-5910; 1873-328X
• DOI: 10.1016/j.powtec.2006.08.018

The dissolution of CO 2 in a polymer causes plasticization of the polymer and hence, its viscosity is reduced. A model based on the free volume theory has been used for a polyester resin, which shows a considerable reduction in the viscosity due to dissolved CO 2. Therefore, supercritical CO 2 has been used as a processing solvent in the continuous production of micron size particles of the resin. Despite the viscosity reduction caused by the dissolved CO 2, an excess quantity of CO 2 with respect to its solubility limit has been used for micronisation of the polymer due to its high viscosity. The mixing of CO 2 and the polymer has not been possible in an extruder at high gas to polymer mass ratios and consequently, a simplified Kenics type static mixer has been used for the mixing purpose. In this study, the effect of various parameters such as temperature, pressure, nozzle diameter and gas to polymer mass ratio on the particle morphology and size has been studied. The experimental results manifest the technological as well as the theoretical insight into the particles production from a high viscosity material. Supercritical CO 2 is used as a processing solvent in the continuous production of micron size particles of a polyester resin. Despite the viscosity reduction caused by the dissolved CO 2, an excess quantity of gas has to be used with respect to its solubility. The mixing of CO 2 and the polymer has been achieved by using a simplified Kenics type static mixer. [Display omitted]