Colour properties and colourfastness of polyester treated fabrics dyed with melastoma malabathricum L. using ultrasound assisted extraction & dyeing methods / Tengku Muna Shaheera Tuan Zainal Abidin

In this study, attempts were made to dye polyester fabric with natural colourants extracted from Melastoma malabathricum L. (or also known as senduduk). The fabric was first treated with sodium hydroxide and chitosan prior to dyeing in an attempt to increase the dye uptake on the structurally compact fibre of polyester. A comparative study in extraction and dyeing using ultrasonic and conventional techniques were investigated. The colour properties of the colourants were measured using colour spectrophotometer and the colour fastness of the dyed fabrics were evaluated for washing, crocking, light and perspiration. It was found that the extracts from ultrasound assisted extraction gave higher yield percentage and exhibited the original colour of the raw material, some 23.81% improvement in the dye yields as compared with the boiling technique. The utilization of ultrasound in dyeing also gave a significant improvement with increased dye uptake and shortened the duration of dyeing. Evaluation from the colour spectrophotometer indicated improvements in L* and K/S values for samples treated with alkaline and chitosan. The alkaline treated fabrics were darker in colour as compared with the untreated and chitosan treated fabrics. Polyester treated with chitosan only gave a significant effect when dyed with the powdered dyes of Melastoma Malabathricum L. The addition of mordant in dyeing polyester with Melastoma Malabathricum L. resulted in some shade variations, from beige to brown. The use of metal mordant, iron II sulphate, gave darker shades and changed the hue of the polyester fabric to grey colour. The ratings for colour fastness to washing were 3 to 5 indicating moderate to good ratings. The staining on polyester and cotton were 4 to 5, which is rated as good.