Evaluation of sub and near critical carbon dioxide for low processing temperature of medical thermoplastic polyurethane

Incorporation of thermosensitive active pharmaceutical ingredients for manufacturing multifunctional polymeric medical device is still limited as they can be deteriorated in the hot-melt extrusion process. In this study, the potential of sub and near-critical carbon dioxide for use as a green plasticiser was investigated. Pellethane thermoplastic polyurethane was hot melt extruded and its thermal and rheological behaviour were evaluated. The resultant extrudates were characterised using parallel-plate rotational rheometry and differential scanning calorimetry. The process temperature decreased from 185 to 160 °C. The rheology indicated that the melt viscosity reduced to 36.36% and 40.04% at 600 and 1000 psi, respectively. The results indicate that the employment of scCO2 as a transient plasticiser is a viable aid to conventional hot-melt extrusion and offers more opportunities for thermosensitive drugs to be coextruded at lower processing temperatures.