Plasma treatment for improvement in dye uptake to enhance sustainability of natural fibres: a review

Nowadays, textile materials cannot be restricted to only clothing and apparels but they find a variety of applications as technical textiles in construction, agriculture, medicine, aerospace and defence services. Natural fibers, in general, are not suitable to be used unprocessed for any application, for e.g., cotton consists of about 10% non-cellulosic impurities like waxes and pigments, similarly, silk fibroin is covered with sericin which needs to be degummed prior to any functional use. Thus, surface modification of natural fibers becomes immensely important as it leads to an improvement in surface properties like wettability, dyeability, crystallinity, softness and many more. Demand for eco-friendly finishing process to develop functional textiles has been gaining popularity in recent times to replace the conventional wet processing techniques which are energy-intensive along with being environmentally harmful and economically expensive. Plasma treatment being a dry, non-toxic, environmentally and worker-friendly option to achieve surface modification without altering bulk properties of the material has assumed profound importance among all available surface modification methods. Plasma which is considered as the fourth state of matter can be defined as a mixture of electrically neutral ionized gas consisting of positive, negative ions, charged particles, and metastable species. In nature, 99% of the matter exists in plasma state but they can also be effectively generated in laboratory and industries. According to various studies, conventional dyeing processes have a low yield of dyeing along with a loss of more than 50% dye effluents in water bodies without proper waste-water treatment. It leads to an aesthetic loss as well as environmental degradation over a period of time affecting the humankind, animals and aquatic life. Plasma treatment has been reported to increase the dye uptake rate of fabric with better diffusivity of dye molecules and better wash fastness of the fabric which ultimately reduces the amount of dyestuff and water necessary for a particular shade. In this study, we present a short review of how various types of plasma treatments can enhance dye uptake of different types of dyes on textile materials. (author)