Dense Gas Processing of Polymers

Abstract

There is a growing global awareness about environmental pollution, and many sanctions and sustainable practices have been implemented. In particular, the use of volatile organic compounds (VOCs) is a practice that is being limited and minimized world-wide. These VOCs are not only damaging to the environment, but are also an occupational hazard. The polymer processing industry is known to use VOCs extensively for polymerization, fractionation, plasticization, degradation, extraction and purification. More environmentally-friendly methods to circumvent the use of these toxic and hazardous compounds are being explored. The use of dense gases in polymer processing can respond to the need for more environmentally-friendly industrial processes. Products with high-purity, sterility, and porosity can be achieved using dense gas technology (DGT). Currently, DGT has been used for different aspects of polymer processing including polymerization, micronization, and impregnation. Due to its high solubility in polymers and diffusivity, dense CO₂ can penetrate and plasticize polymers, whilst impregnating them with low-molecular weight CO₂-soluble compounds. The dense CO₂ properties of inertness, non-toxicity, and affinity for various therapeutic compounds are specifically advantageous to the medical and biomedical industries. Biodegradable polymers and other medical-grade polymers have benefited from the application of DGT. The aim of this review was to show the versatility of dense CO₂ for polymer processing applications, specifically polymerization, polymer blend preparation, drug loading and sterilization.

Keywords:

• polymer processing
• supercritical fluids
• dense gas
• supercritical CO₂
• dense CO₂
• polymer impregnation
• polymer blends
• dense gas technology

Acknowledgments

The authors would like to thank the Australian Research Council for financial support from the Discovery Grant (Reference DP0665514).