Effect of Helium-Oxygen Plasma Treatment on Physical and Chemical Properties of Cotton Textile

Plasma, an ionized gas composed of ions, electrons, photos, UV radiation and neutral active species, can be used for nano-scale surface modification of textile substrates without using water. Among the various types of plasma, only atmospheric pressure cold plasma (non-thermal plasma) is suitable for surface modification of heat sensitive textile substrates in a continuous manner. Atmospheric pressure cold plasma was generated in the presence of helium-oxygen (He/O₂) mixture and cotton fabric was plasma treated for 30 s to 4 min. Upon ionization, helium (He) emits photons at wavelengths of 706 nm, 667 nm, 587 nm, 727.5 nm and oxygen at 776 nm and 844 nm. After plasma treatment, cotton became more hydrophilic due to generation of hydrophilic groups resulting better water wicking. Plasma treatment increases the surface crystalline index (CI) from 1.09 in the untreated sample to 1.65 in the 2 min He/O₂ plasma treated sample. Scanning electron microscope (SEM) images showed etching of fibre surfaces. In the 2 min and 4 min He/O₂ plasma treated samples, there was an improvement in colour value in terms of K/S, a* and c*. Surface crystalline index (CI), numbers of hydroxyl and carbonyl groups play an important role in colouration of cellulosic textile using reactive dye.