Study On Biologically Refining Technology Of Jute Fiber

Jute fiber is a kind of natural cellulose fiber with excellent properties, which make it an ideal textile material.However,the single jute fiber is too thin and short to spin into yarns.Jute fibers have to be used in the form of technical fibers.There are high contents of noncellulose components in jute fiber,that is,hemicellulose,lignin,pectin,and others, which make the jute fiber quite coarser.Therefore,jute fibers have to be refined to utmostly decrease the contents of noncellulose components,so as to make the fiber thinner.At present,the main methods to refine jute fibers can be classified into three:mechanical method,chemical method, and biological method.The biological method,as well as biological-chemical method,is mainly discussed in this paper.The process used in this paper can be summerizied as:pretreatment→compound enzyme treatment→biological-chemical treatment→bleaching→refined jute fiber.The main conclusions achieved from the researches in this paper are summerized as follows.1.Four kinds of enzymes,i.e.laccas,cellulase,xylanase and pectinase,are used individually for biological treatment of jute fibers. Experimental results show that the treatment by laccas is most effective. In addition,the processing parameters of laccas treatment are optimized with solution pH of 5.0 and concentration of 1.5%,treating temperature of 65℃,treating time of 120min and bath ratio of 1:15.The fibers after treated have linear density of 24.71 dtex,breaking stength of 3.56 cN·dtex^-1,and breaking elongation of 3.10%.2.The effects of compound enzymes are studied by adding two alkaline enzyme,pectinase and xylanase,into the solution synchronously or step by step,which are called one-step processing and two-step processing,respectively.The experimental results show that one-step method is better than the two-step one,in terms of linear density, breaking strength and residual gum content of treated fibers.Furthermore, the processing parameters of compound enzymes treatment can be optimized as:the total concentration of pectinase and xylanase is 1.0% with their proportion of 2:1,solution pH is 8.0-8.5,treating temperature is 55℃,treating time is 120min and bath ratio is 1:15.The jute fibers after compound enzymes treatment have liner density of 23.55dtex,breaking strength of 3.73 cN.dtex^-1,breaking extension of 2.38%,and xylogen content of 8.25%.3.Jute fiber after compound enzymes treatment are further treated by chemcial method.The process parameters can be experimentally optimized as:NaOH concentration is 10g/L,Na₂SiO₃ concentration is 2g/L,Na₂SO₃ concentration is 1g/L,treating temperature is 90℃,treating time is 45min,and bath ratio is 1:15.With the optimized process condition,the jute fiber has improved properties,with the liner density of 16.32dtex,breaking strength of 3.61cN.dtex^-1,breaking extension of 2.32%,and xylogen content of 7.43%.4.The jute fiber after biological-chemical treatment are also bleached to improve their whiteness and spinnablity.The fiber are firstly pretreated by xylanase,and then bleached by H₂O₂.The experimental results show that the pretreatment with xylanase can reduce the concentration of H₂O₂ and NaOH when bleaching jute fiber.In addition, the pretreatment process can be experimentally optimized as:xylanase concentration is 0.4%,treating temperature is 60℃,treating time is 60min,pH is 8.5,and bath ratio is 1:15;and the bleaching process as: H₂O₂ concentration is 8 g/L,NaOH concentration is 6 g/L,Na₂SiO₃ concentration is 4g/L,JFC concentration is 1g/L,treating temperature is 60℃,treating time is 90min,and bath ratio is 1:20.With the optimized process condition,the jute fiber has modified properties,with the linear density of 15.31dtex,whiteness of 43.4,breaking strength of 2o42cN.dtex^-1, residual gum content of 5.23%,and xylogen content of 6.82%.