Optimisation of nitrogen plasma exposure time for surface modification of cotton fibre

Surface modification via plasma treatment is useful in improving textile-based wound dressing functionality. This study was conducted to optimise the nitrogen plasma exposure time and its effect on the cotton surface (CS) properties at a constant nitrogen flow rate of 20 sccm for 5 to 30 min. The optimisation was done by analysing the alteration in morphology, functional group composition, crystallinity phase, electrokinetic potential, and colour of CS as subjected to nitrogen plasma. CS experienced an etching effect due to the presence of microcracks on its surface, with its electrokinetic potential becoming less negative, ranging from -5.51 to –8.05 mV. Then, the nitrogen functional group was detected on CS ranging from 2.9% to 4.5%, with its whiteness index reduced to 8.67% compared to the pristine cotton. As a result, 20 min was selected as the optimum exposure time for surface treatment. An exposure time of 30 min showed an early sign of degradation, which reduced its crystallinity index by 11.1%. Apparently, the CS is activated as exposed to the nitrogen plasma and experiences slight changes in its molecular structure without affecting its bulk properties.