Analysis on the dyeing of polypropylene fibers in supercritical carbon dioxide

Polypropylene fibers were dyed in supercritical carbon dioxide system and t he results were compared with those of fiber dyed in water system. Dye upta ke value calculated by a UV spectrum indicated that polypropylene fiber dye ing was much better in carbon dioxide than in water. Optical microscopical analysis showed that dye molecules had diffused thoroughly into fiber in CO 2 because of the excellent compatibility between the dye and the CO2. X-ray and birefrigence analysis demonstrated that plastification caused by the i mplementation of CO2 made molecular chain more mobile and led to an increas e in the dyeing of polypropylene fibers. Moreover a mechanical test and DSC analysis indicated that the fiber structure was not damaged when the fabri c was dyed at 100 degreesC. Hence dyeing polypropylene using CO2 as a trans port medium was very feasible and worthy of further development.