湖工院纺织材料学课件02天然纤维

Chapter2Naturalproteinfibers

Allproteinfibersarecomposedofaminoacidsthathavebeenformedintopolypeptidechainshavinglargermolecularweights.

Fibersinthisgrouphaveexcellentabsorbance.Theirstandardmoistureregainishigh,andtendtobewarmerthanmostotherfibers.Animallifeisthesourceofnaturalproteinfibers.2.1Wool

Woolwasprobablythefirstanimalfibertobemadeintocloth.Theartofspinningwoolintoyarndevelopedabout4000B.C.andencouragedtradeamongthenationsintheregionoftheMediterraneanSea.2.1.1MolecularstructureChemicalcompositionandmolecularstructureofwool（1）化学组成蛋白质角朊；C、H、O、N、S元素组成。（2）单基R侧基—多、复杂，约25种氨基酸。（3）空间形态：羊毛的稳定结构是α型，α型加外力——β型，β型去外力——α型；分子间力——羊毛：范德华力、盐式键、氢键、硫键力2.1.2WoolstructureThewoolfibercrosssectionmaybenearlycircular,butmostwoolfiberstendtobeslightlyellipticalorovalinshape.Woolfibershaveanaturalcrimp,abuilt-inwaviness.Thecrimpincreasestheelasticityandelongationpropertiesofthefiberandalsoaidsinyarnmanufacturing.Woolisanextremelycomplexfiberthathasevolvedfromnatureovermillionsofyears.Thefibersthatmakewoolsousefularegeneticallybuiltintoeveryfiberonthesheep,andhencedependlargelyonthebreed.Noman-madefiberhaseverbeenabletoduplicateallofwool'sspecialcharacteristicsatonetime.形态结构：

羊毛由鳞片层、皮质层、髓质层组成。Theinnerlayerofwoolfiberisdividedintohalves-theparacortexandortocortex.Thesetwocellsabsorbmoisturetodifferentextentshencetheyexpandandcontractbydifferentamountscausingbendingofthefiber,whichresultsinacrimppatternalongthelengthoffiber.Athighermagnificationofwool

2.1.3Woolproperties1.Chemicalproperties:

Woolprotein,keratin,ishighlysusceptibletodamagebyalkalies.Solutionsof5percentsodiumhydroxideatroomtemperatureandsodiumhypochloritebleach(fullstrength)willdissolvethefiber.Woolisconsideredresistanttoactionbymildordiluteacids,butstrongconcentratedmineralacids,suchassulfuricandnitric,causebreakdownanddecompositionofthefiber.(1)酸的作用:稀酸对羊毛的强力几乎无损害,但不耐强酸,有机酸更缓和,常用作促染剂.(2)碱的作用:碱对羊毛将的作用比较剧烈.弱碱则比较缓和,在染色工艺中常使用.2.Finenessofwoolfiber:7-240µm(1)细度的表示方法ａ．品质支数：原：羊毛实际可能纺得的支数．现：直径在某一范围内的羊毛．ｂ．平均直径：Or:N=∑ni

纤维总根数均方差:Or:变异系数CV：c.公制支数Nm:而:S----纤维截面积(µm2)γ----纤维密度(g/cm3)故:(2)羊毛细度与成纱质量及产品性能关系1)成纱强度:纤维细,成纱强度大.2)成纱条干:纤维细,成纱条干较均匀.3)成纱支数:纤维细,成纱支数高.4)产品性能:视用途TheEnglishorspinningcountsystemTheEnglishsystemofgradingwoolprovidesnarrowerrangesandamoreexactnomenclaturethantheAmericansystem.Itusesameasurementcalledthe“spinningcount”andisbasedonthenumberof“hanks”ofyarnwhichcouldbespunfromonepoundofcleanwoolontheequipmentavailableatthetimethesystemwasdeveloped.Aswoolbecomesfiner,morehanksoryardsofyarncanbespunfromapoundofcleanwoolandthespinningcountbecomeslarger.Intheory,onepoundofclean62sspinningcountwoolcouldproduce62hanksor104,160feetofyarn.(Ahankofyarnis560yardsinlength.)Althoughwoolisseldomspuntoitsmaximumcount,thereisalimittothenumberoffiberswhichwillholdtogetherinyarn.TheEnglishorSpinningCountsystemofgradingwoolprovidesanumericaldesignationoffineness.EnglishorSpinningCountgradesofwoolcommonlyusedintheChinatodayare:80s,70s,64s,62s,60s,58s,56s,54s,50s,48s,46s,44s,40s,and36s.SymbolsofqualityusedonmerchandisemeetingthespecificationsoftheWoolBureau.2.2SilkSilkwormsareusuallycultivatedandareraisedundercontrolledconditionsofenvironmentandnutrition.Theirfoodconsistssolelyofmulberryleaves.Thesewormsproducethefinest,silkiestfibers.Tokeepthesilkinonecontinuouslength,thewormsinthecocoonsarekilledbyheatbeforetheyarereadytoleave.Somemoths,however,areallowedtobreakoutofthecocoontoproducetheeggsforthenextcropofsilk.Cocoons蚕的发育与蚕茧的形成蚕的发育：经过卵、幼虫、蛹和成虫（蛾）四个阶段。茧的形成：

由外→里分三层茧衣（外层）：蚕吐丝时，最初吐出的凌乱的丝缕，成为茧的蓬松外廓。（丝缕细，强度差，丝胶含量多，绢纺原料）茧层（中层）：茧衣里面，丝缕绕成丝圈，结构紧密，排列规则，是丝的主体。（丝较粗，强力好）

蛹衬（内层）：

吐丝将近终了时叠合成的疏松层。（丝最细，发脆，丝胶含量少，绢纺原料）

蚕丝细度分布不匀

外层：中层：内层＝1.1：1.5：0.82.2.1蚕丝的品种2.2.2蚕丝的形成和形态结构丝：蛋白质丝素（70-80%），少量丝胶（20-30%）；

柞蚕丝——丝素85%蚕丝;丝素外包有丝胶；

纵向平滑，截面为不规则三角形Longitudinalviewandcrosssectionofsilk2.2.3蚕丝的分子结构C、H、O、N元素组成。蚕丝：少、简单，约18种氨基酸。蚕丝的稳定结构是β蚕丝：范德华力、盐式键、氢键结晶、取向——羊毛的结晶度、取向度低，而蚕丝的较大。2.2.4茧的加工1.混茧:将性能近似的原料混合,保持性能稳定,提高生丝质量.2.剥茧:剥去茧衣,一般茧衣约占蚕茧的2%,它可作绢纺原料.3.煮茧:用水或药剂使丝胶适当溶解,使茧丝从茧上层不乱地退解下来.4.缫丝:将煮熟的茧子经过理绪,找出正绪,使蚕丝由茧层离解,使茧丝从茧层上几曾依次不乱地退解下来.复整:在复摇机上,把缫制的生丝,制成一定规格的丝绞.2.2.4蚕丝的性能1.长度:春蚕900-1200m,夏秋蚕650-900m,柞蚕400-1000m.平均800m.2.细度和均匀度(1)实际纤度Da(2)平均纤度

____低于平均纤度的小绞丝的平均纤度.n1____低于平均纤度的小绞数.3.强伸度:断裂长度22-23km,断裂伸长15%-25%.吸湿后,桑蚕丝强度下降,而柞蚕丝强度上升.断裂伸长均明显增加.4.吸湿性:较强9%-13%,丝胶的吸湿>丝素的吸湿.5.触感与光泽:光滑有弹性