The process of dyeing poly(ethylene terephthalate) - PET films at 50, 60 and 65ºC and poly(hydroxybutyrate) - PHB granules at 60, 70 and 80ºC using supercritical carbon dioxide (scCO2) as solvent and ethanol as cosolvent was studied by DSC, TGA analysis and measurements of shrinkage to determine the morphological modifications caused by the scCO2 treatment of these materials. A comparison of the effects of annealing both polymers in scCO2 provided evidence that PHB had plasticization activity due to its crystallinity and that PET favored the dyeing process at high pressure when its temperature was raised to close to the Tg value. DSC and TGA measurements were obtained for all the samples. The DSC results showed that there was no significant structural change and the TGA data showed that thermal stability was not affected in the samples analyzed.
Supercritical CO2; PET films
