The Improvement Of Wool Performance By Laccase Catalyzed Reaction Of Phenolic Compounds

Wool is a kind of keratin fiber,which has excellent properties such as soft,warm,moisture absorption,etc.,and is favored by consumers.However,wool fibers are easily damaged during processing,thus reducing its strength and performance.In particular,the dyeing processing of protein fiber is up against the urgent problems of fiber damage and large amount of sewage discharge.Therefore,this paper intends to establish a new enzymatic dyeing system by using biocatalyst laccase,which can improve the performance and function of wool fiber,and realize the ecological low-carbon dyeing of textiles at the same time,and finally widen the application range of wool fiber.First,the chemical reagent catechol was polymerized under the catalysis of laccase,and cross-linked with amino and hydroxyl groups in protein macromolecules.The optimum parameters of enzymatic dyeing of wool fiber were investigated and the effects of different pretreatments on enzymatic dyeing properties of wool fibers were discussed.Then the optimal technological parameters of enzymatic treatment were obtained: reaction time 5 h,reaction temperature 40 ℃,p H 5.5,laccase concentration 50U/m L,catechol concentration 0.04 mol/m L.It was found that with the cooperation with pretreatment process,the diffusion and deposition of enzyme oligomer on the yarn surface were more uniform,and the dyeing depth increased,and the tensile strength increased by 17 % and 26 %,respectively.Compared with dyed wool fibers without pretreatment,the tensile strength of the wool fibers pretreated by plasma was increased by 10 %,and the elongation of fiber was not affected.Secondly,tea polyphenol which extracted from green tea was oxidized under the catalysis of laccase,and then dyed wool.The differences between tea polyphenol and catechol in dyeing,strength and thermal properties of wool fibers dyed by enzymatic were discussed.And the structure of dyed wool was also characterized by SEM,XRD and Raman spectra.The results showed that using catechol and tea polyphenol as the target substrates,and under the catalysis by laccase,wool yarn could be dye into dark brown or brown yellow.When the concentration of catechol and tea polyphenol was 0.15 mol/L and 0.05 mol/L,the tensile strength of dyed wool reached the maximum value,which was increased by 21 % and 32 % compared with the raw wool,respectively.And the abrasion resistance and heat resistance of wool were also improved,but the elongation decreased.Compared with catechol,tea polyphenol is extracted from tea resources,green and non-toxic,and achieve higher strength enhancement to wool yarn and less elongation loss,so it is the optimization substrate for enzymatic dyeing reaction.The Raman and XRD analysis showed that the content of β microcrystals in the secondary structure of the fibers increased after enzymatic treatment,while the content of α microcrystals decreased,resulting in the increase of strength and decrease of elongation of the fibers.Thirdly,the repair ability of enzymatic treatment to damaged wool was further studied.The damage of wool fiber in blenching or anti-felting finishing by chemical and biological was simulated by pretreatment using sodium dithionite and proteinase reagent.Then,tea polyphenol catalyzed by laccase were used to cross-link damaged wool fiber,and the effects of enzymatic treatment on strength,disulfide bond and alkali solubility of the damaged wool fiber were discussed.The results show that the fiber flake layer and internal structure are damaged after sodium dithionite and proteinase pretreatment,resulting in disulfide bond fracture and strength reduction.But the crosslinking using tea polyphenol catalyzed by laccase significantly increased the tensile strength and elongation of the fiber,and the disulfide bond concentration increased,which could effectively repair the chemical or biological damage of the fiber in processing.Finally,due to the disadvantages of strength enhancement and elongation reduction of enzymic dyed wool fiber,tyrosine was used as fiber elongation enhancement agent to coordinate tea polyphenol oxidation and crosslinking with wool.Fluorescence and FTIR spectra showed that under the catalysis of laccase,the cross-coupling reaction between tea polyphenol and tyrosine occurred,and the content of tyrosine in the cross-linked wool macromolecular increased,and the molecular quantity of wool protein increased.With cooperation of tyrosine,the strength of cross-linked wool fiber was 24 % higher than that of raw wool,and damage of elongation was reduced to 4 %,so the tyrosine effectively improved the damage of fiber elongation.At the same time,the presence of tea polyphenol endows the fiber with better oxidation resistance,UV resistance and hydrophilicity.