The Research On The Dyeing Property Of PLA Fiber And Its Textiles

A pillar-like diffusion model was proposed by studying the dyeing performance and mechanism of PLA fibers.A dyeing dynamics model was build up by using Fick's second law and two parameters,K and M,of this model were related to dyeing affinity and diffusion coefficient,respectively.Effects of dyeing conditions, such as dying rate,temperature,pH,electrolyte concentration and the auxiliaries,on dyeing performance was also investigated intensively.Linear Beer-Lambert relationship was established and the dye concentration was determined by spectrophotometer.The dyeing uptake ratios of 16 different dyes, such as C.I.Disperse Red 74,were also determined.Factors influencing the stability of disperse dye were also investigated systematically.Weight average particle size, Dw,and weight specific surface area,Sw,were measured.The dispersing stability of dyes in the presence or absence of auxiliaries was studied,showing that auxiliaries can promote the dispersing stability of dyes.The technological process of dyeing PLA and its blended fabrics with disperse dyes was developed by studying bleaching process of PLA/cotton blended fabric. Process conditions such as pretreatment,dyeing and reduction were also optimized. One-step and one-bath approach was applied to pretreat the fabrics.The particle size of Dytar Dianix Yellow XF dye was determined by using JL9200 laser particle size instrument.Results showed that average particle size is about 0.85μm and particle size obeys normal distribution.85%of dye particles are of size smaller than 0.98μm.By contrast,the particle size of three domestic dyes are found to be larger than 1.6μm and the cumulative average particle size is basically between Dav=8-10μm,which is 9 times of imported dyes.An homogeneous and stable disperse dye solution can be obtained by grinding the dye beforehand.The ratio of dye uptake can be increased by 10%after grinding dyes.The glass transition temperature of PLA fiber was determined to be 71.30℃by DSC thermal analysis.As shown in DSC curve,there are two large absorption peaks at 161.21℃and 168.68℃,suggesting the existence of two crystal phases in the fiber.CI Disperse Blue 56 has the lowest dye uptake ratio and the dye uptake ratio of C.I Disperse Red 74 follows the fall-rise-fall trend.DSC analysis also showed that PLA fiber has poor thermal stability,melted at about 158℃.As a result,it is necessary to avoid high temperature treatment in dyeing PLA fiber,preventing the deterioration of the fiber.The dye uptake ratio,half-dyeing time and diffusion coefficient of C.I disperse Red 74 on PLA fiber were determined.The results were validated by the Hill equation.The dyeing thermodynamics and dynamics on PLA fiber were investigated in the presence of auxiliary.The diffusion coefficient D of dyes on PLA fiber was measured at different times of dyeing process.The dyeing-rate curves and adsorption isotherm were plotted.The PLA dyeing thermodynamics parameters were studied at the different dyeing conditions,so their effective adsorption volume was measured and their dyeing affinity,heat and entropy were calculated.