The Structure And Dyeing Properties Of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate/poly Lactide Blended Fibers

To improve the heat resistance and flexibility of polylactic acid(PLA)fiber,poly(3-hydroxybutyrate-co-3-hydroxyvalerate/polylactic acid(PLA/PHBV)blended fiber attracted attention of researchers.Therefore,it was necessary and meaningful to study its dyeing properties.In this paper,the microstructure and thermal properties of PLA/PHBV blend fiber were analyzed and compared with PLA fiber.Commercial disperse dyes with low-energy,medium-energy and high-energy were used to study their dyeing properties,including dyeing rate,build-up property and color fastness.Five novel disperse dyes containing different characteristic groups as well as bearing the same chromogen were synthesized in the laboratory for the dyeing of PLA/PHBV blended fibers.The dyeing rate curve with increasing temperature,adsorption isotherm,chroma properties and washing fastness were measured respectively,to reveal the influence of characteristic groups on the adsorption properties.The two components in the PLA/PHBV blend fiber were in the form of a microphase separation,the PLA parts show similar crystal structure but higher crystallinity than the PLA fiber,and the PHBV phases form lower crystal structure.Therefore,the glass transition temperature of the blended fiber was slightly lower and the melting point was slightly higher as compared with that of the PLA fiber.The decomposition temperature of the PHBV segment in the blend fiber was lower,while the decomposition temperature of the PLA segment was higher than that of the pure PLA fiber.The lower glass transition temperature of the blended fiber enabled the disperse dyes in different energy levels to reach the dyeing equilibrium at a temperature of 100 °C,which was lower than the dyeing equilibrium temperature of the PLA fiber(110 °C).Meanwhile,the blended fibers dyed with high-temperature disperse dyes showed lower dyeing transition temperature at 70 °C than that of PLA fibers at 80 °C.Five new disperse dyes with different characteristic groups showed different dye uptake rates and adsorption behaviors on the blended fibers.The three disperse dyes with larger molecular volumes,including urea group,carbamate and ester group,showed lower dyeing rate.The dyes exhibited increased color uptake after 90 °C,then reached the dyeing equilibrium after helding for 30 min at 110 °C.However,the two dyes containing amino and hydroxyl groups showed obvious color uptake at 50 °C,and reach the dyeing equilibrium at90 °C.In terms of adsorption isotherms,the dyes containing urea group and carbamate group followed a complex adsorption models of Nernst and Langmuir,the adsorption of three dyes containing ester group,amino group and hydroxyl group were accordance with the Nernst type.When the concentration of the dye solution was low,the three dyes containing hydroxyl,carbamate and amino groups exhibited the similar adsorption ability,the dyes containing ester group was lower,and the lowest was the dyes containing urea group.With the increased concentration of the dye solution,the two dyes containing ester and amino groups reached saturation,and the adsorption amount of three dyes containing urea groups,carbamate and hydroxyl groups increased continually.The hydroxyl-containing dyes had more serious aggregation,whose adsorption capacity was higher.The ester-containing dyes also aggregated in certain extent.However,dyes containing carbamate,urea and amino groups were relatively less aggregated.The change fastness to washing of the PLA/PHBV blended fiber fabrics dyed using 5dyes was generally low.Dyes containing ester group showed the lowest change fastness to washing,dyes containing carbamate and amino groups were better,and dyes containing hydroxyl group were the best.Dyes containing urea group showed better color fastness to washing,which was attributed to their less adsorption.The staining fastness of ester-containing dyes was relatively the best,and hydroxyl-containing dyes were the worst.Other dyes showed better fastness performance except severe staining on nylon.The results of dyeing performance showed that carbamate-containing dyes exhibited good adsorption performance on PLA/PHBV blended fibers,and further in-depth research on the structure-activity relationship was necessary to obtain more ideal structural model,which was suitable for PLA/PHBV blended fibers.