Surface modification of cotton yarn with a DC glow discharge in ambient air

A direct-current atmospheric pressure glow discharge is used for surface treatment of cotton yarn. The envisaged plasma effect is an increase in the surface energy of the treated material, leading e.g. towards a better wettability, adhesion or dyeability. The electrode geometry is that of a negative corona with a plane anode and a cathode that consists of a single row of electrode pins in the direction of the yarn. In order to test the efficiency of the plasma treatment, the resulting degree of hydrophilic behaviour of the treated cotton is quantified by a wicking rate test. The influence of power, treatment time and yarn position on the plasma effect and its stability in time is assessed. The results show that the wicking rate increases with treatment time and discharge power. The wicking rate tends to be higher in the vicinity of the electrodes. The variation of the plasma effect in the direction of the air flow reflects the asymmetry in the plasma profile due to the transverse gas flow, which has a velocity of 40 m/s.