**5. Conclusions**

The present paper has described the results of dyeing behaviour for plasma treated nylon, polyester and cotton fabrics. Mainly air, nitrogen and oxygen gases were used together with vapours of acrylic acid in a low pressure atmosphere. There is substantial enhancement in the dye uptake of nylon fabrics. This result is similar to the observation when plasma processing is done in APGD. In case of polyester and cotton, however, the enhancement in the dye is not substantial. Rather the type of dye (acid, disperse or natural) played an important role.

The survey of literature as well our own work regarding the effect of plasma on dyeing behaviour shows that whereas there is always enhancement in the dye uptake of wool fibers, it is not necessarily so for polyester, cotton and other fibers. Although etching of surface, creation of voids and formation of C=O, COOH, OH groups occurs to facilitate higher dye uptake, there exist competing processes of increased crystallinity and crosslinking on the surface which may not allow the diffusion of the dye molecules. Therefore the selection of the fibre, nature of gas, process time and the type of dye all play a major role. Thus clear understanding of plasma process is of utmost importance to utilize the technology on the industrial scale. Further the type of plasma i.e plasma produced by different power sources like A.C., D.C., low pressure, atmospheric pressure gives more or less similar results as far as dyeing property is concerned, although morphology and structural differences are observed.
