Dyeing behaviour of poly(ethylene terephthalate) fibres in supercritical carbon dioxide

A new type of poly(ethylene terephthalate) fibre was developed via a high-speed spinning technique, The dyeing behaviour of this fibre in supercritical carbon dioxide was compared with that of a fibre produced by conventional methods. At lower temperature and pressure, the high-speed spun fibre, which had inherently larger crystallite sizes and lower birefringence, showed a larger dye uptake. However, when the supercritical conditions were elevated to 125 degreesC and 230 bar, the dye uptake of both types of fibre increased markedly and the difference in dye uptake between the fibres was reduced, The new type of fibre showed slightly higher grades in sublimation fastness tests.