Use of a carbon dioxide laser for environmentally beneficial generation of distressed/faded effects on indigo dyed denim fabric: Evaluation of colour change, fibre morphology, degradation and textile properties

Abstract

Denim garments are particularly popular with the younger population of adults. Distressed or worn out effects have been and will continue to be popular with this market sector. These faded or worn effects have been achieved using a range of physical, chemical and mechanical finishes. Both wet and dry finishing of denim fabrics and garments pose severe environmental and health risks. Recently, environmentally beneficial decolourisation/ablation methods for denim fabrics have been investigated. Such methods have included plasma, laser, and ozone treatments. Researchers in this field have highlighted the potential of CO2 laser treatment of 100% cotton denim, however the textile performance post-treatment has not been properly investigated. In this study, light, medium and heavy weight indigo dyed 100% cotton denim fabrics were exposed to a CO2 laser at a range of power and intensity levels. Colour change was investigated using a Spectrophotometer, morphological structural analysis was carried using Scanning Electron Microscopy, and attenuated total reflectance Fourier transform Infrared spectroscopy (ATR-FTIR) was used to monitor the loss of indigo dye and degradation of the cellulose fibres. The thermal-oxidative degradation behaviour of fabrics was also studied using differential scanning calorimetry to obtain oxidation onset temperature. In addition, several fabric performance assessments were carried to evaluate tensile strength, colour fastness, air permeability and thickness. Findings reveal that the grayscale rating, which is the tone density and hence laser power affected the colour change and as the grayscale increased, the colour fading was higher and affected the fabric performance across all fabric weights. Based on this, the research recommends an optimum set of laser processing parameters to produce stressed or faded denim effects without compromising the fabric performance. This research demonstrates that faded effects on denim can be produced with low environmental and health risks.