The current research studied the dyeing properties and spectroscopic characteristics of natural dyes on PLA and PET fabrics. The natural dyes used were the dyes extracted from turmeric and cassumunar powder and the commercial dyes viz. Natural Orange and Natural Red Brown. The water solubility and partition of the dyes in octanol and water (logP) were studied. It was found that the dyes with poor water solubility that were the turmeric and cassumunar dyes exhibited a high degree of exhaustion and visual color yield (K/S) than the readily water soluble commercial dyes viz. Natural Orange and Natural Red Brown. Turmeric and cassumunar dyes can be used for dyeing PLA and PET fabrics to a medium-deep shade with the turmeric dye providing a deeper shade. The fluorescence properties of the turmeric and cassumunar dyes were examined on the PLA and PET fabrics and it was observed that the dyes exhibited a stronger fluorescence emission on PLA than PET for both turmeric and cassumunar dyes. Cassumunar dye displayed less fluorescence properties than turmeric dyes on both fabrics. The fluorescence emission properties of the turmeric dyes at different K/S levels were also investigated.Index Terms-Natural dye, polyester, polylactic acid, turmeric, cassumunar, fluorescence.

This study investigated the effect of chitosan and turmeric dye on UV protection properties of polyester fabric. The results of chitosan treatment on undyed polyester fabric showed that the UPF values increased with increasing chitosan concentration. Apart from being a promising natural dye for polyester, turmeric dye was found to be an outstanding UV protection agent with almost 100% UV blocking. A study on the effect of chitosan on the properties of turmeric-dyed fabric indicated that chitosan caused a slight change of turmeric dye shade on the fabric but had no effect on UV protection properties of the fabric.