**3.3 Effect of PET fabric dyeing conditions (High temperature conditions)**

Plasma treatment alone increases the hydrophilicity of PET fabric, demonstrated by the decrease in water contact angle from 80° to 45°. However, after 30 minutes of immersion in water at R.T.P there is an increase in water contact angle from 42° to 55°, and a considerable decrease in capillary weight from 360 to 80 mg. Thus, the polar species formed as a result of plasma treatment are gradually lost during washing even at R.T.P. Under dyeing conditions, that is washing at 90°C for 30 min, the wettability of the plasma treated PET reaches that of untreated PET fabric (water contact angle=80°) meaning that there is complete loss of all polar species formed by plasma treatment. Surface analysis of plasma treated PET subjected to hot aqueous dyeing conditions shows complete disappearance of the scaly shaped PET surface (Fig. 15b). Only traces or finger prints of the scales remain leaving a smooth surface (Ra = 38 nm). Moreover dyeing of plasma treated PET shows no increase in disperse dye uptake.
