Application Of Ultrasonic To The Dyeing With Natural Dyes

This paper studied the mechanism of ultrasound dyeing on PTT and PLA fabrics,from the effects of the ultrasound radiation on dissolution and dispersion properties of emodin natural dyes,fiber micro-structure respectively. The optimum dyeing process on PTT and PLA fabrics with natural dye and ultrasound,the effect of ultrasound on the fastness of dyed fabrics were studied in this article.Firstly, the effects mechanism of ultrasound on emodin dyestuff was studied by solubility and grannlarity in aqueous solution of emodin dyestuff through UV-vis Spectrophotometer and Laser particle size analyzer. Morphology,chemical structure,crystalline morphology,thermal performance of PTT and PLA fibers subjected to ultrasound radiation through SEM,FTIR,XRD,TGA and etc The results showed that the ultrasound reduced the size of emodin dyestuff,and improved the solubility of emodin dyestuff in water; Short time of ultrasound treatment cannot change the chemical structure of PTT and PLA fibers, but the content of oligomers on the surface of PTT and PLA fibers decreased after ultrasound treatment. The ultrasound treatment couldn't change the crystal structure of PTT and PLA fibers,but their crystallinity decreased slightly. The thermal properties of PTT and PLA fibers had a little change. The breaking strength of PTT and PLA fibers decreased after ultrasound radiation,but the degree of strength lost not large and still meet the need of fibers.Second,the effect mechanism of ultrasound on dyeing process was studied by the kinetics of PTT and PLA fiber dyed with emodin. The paper found that, when the PTT fiber dyed with emodin at 65℃,the ultrasound dyeing rate constant showed 22.9% higher than conventional dyeing,half-dyeing time shorten by 65.09%,diffusion coefficient increased 3 times,activation energy decreased by 34.07%. While the PLA fiber dyed with emodin at 65℃,the ultrasound dyeing rate constant showed 25.38% higher than conventional dyeing,half-dyeing time shorten by 62.42%,diffusion coefficient increased near 2 times,activation energy reduced by 42.25%.The dyeing rate constant and diffusion coefficients of dyes were increase with ultrasound treatment,and decreased the dyeing activation energy and half-dyeing time.Lastly,this paper took the PTT and PLA fabrics as the research objects for ultrasound dyeing. The optimum dyeing process on PTT and PLA fabrics with ultrasound were established by the single factor analysis. Meanwhile,the effect of ultrasound on the fastness of dyed fabrics with the optimum dyeing process,such as rubbing fastness,washing fastness and light fastness was analyzed. The research results indicated that the optimum dyeing process of PTT fabrics was that,0.3875W/cm2 of the ultrasound power and 40kHz of the ultrasound frequency,dyeing with 3%(owf)of emodin natural dyes at 65℃for 60min. The optimum dyeing process of PLA fabrics was that,0.3875W/cm2 of the ultrasound power and 40kHz of the ultrasound frequency,dyeing with 5%(owf)of emodin natural dyes at 65℃for 60min.Compared with conventional dyeing process ,ultrasound dyeing process can increase the uptake and K/S value of dyed fabric significantly and save dyeing time.The ultrasound can raise 0.5 grades of light fastness of dyed fabric,but has a little effect on the rub fastness and washing fastnes of dyed fabric.