紡織材料學(xué)課件：第8章 常用纖維簡(jiǎn)介與纖維鑒別

1、第八章 常用纖維簡(jiǎn)介與纖維鑒別 第一節(jié) 纖維素纖維（棉、麻、粘膠）第二節(jié) 天然蛋白質(zhì)纖維第三節(jié) 常用化學(xué)纖維第四節(jié) 纖維鑒別Fibers and their propertiesNatural protein fibershigh resilienceability to do work against restraining forces during returning from deformed stateHygroscopic or hydrophiliclikes water and absorbs waterHigh heat of wettingMost mechanical p

2、roperties change when absorbing waterFibers and their propertiesNatural protein fibersHarmed by alkalis, e.g. NaOHHarmed by chlorine bleach & perspirationWeakened & yellowed by UV lightNot readily flammableFibers and their propertiesNatural cellulose fibersHigh moisture absorptionMechanical properti

3、es change up on water absorptionSwells in water but reversible upon dryingHigh resistance to alkaline degradationLow resilienceFibers and their propertiesManufactured cellulose fibersLow tenacityMuch weaker when wet than dryLow abrasion resistance Medium resistance to UV lightDry cleaning or gentle

4、cycleFibers and their propertiesSynthetic fibersLow moisture regainLowest softening temperaturesHighly oleophilic (love oil) & hydrophobic (hate water)Highest electrical resistivityHighest toughnessMedium to high resilienceHigh resistance to moths, meldew & fungi第一節(jié) 纖維素纖維（棉、粘膠） Cotton Fibers Introdu

5、ctionCotton: seed hair obtained from the boll of the cotton plant 4000 fibers/seed, max 20,000 fibers/seed250,000 fibers/bollTypes: Commodity: UplandLong staple: Pima-Su PimaSea islandEgyptianOther: naturally coloredIntroductionApplication: 55% of apparel fibers are cotton70% of mens apparels made o

6、f cotton40% of womens apparels made of cotton65% of all cotton fibers were used for apparels in 1990Additional 27% of cotton for sheets and towels or other non-apparel household applications7% for industrial useStructureCotton fiber: single plant cellMacrostructureStaple length: 1/8” - 2.5” (0.32 -

7、6.35 cm)Cotton fibers used in textile yarns: 7/8” - 1.25”Diameters: 16 - 20 mm but varies from fiber to fiber: longer fibers are finerLength to breadth ratio: 6000:1 to 350:1Relatively uniform along its lengthColor: never truly white but creamy white to grayStructureMicrostructureFlat, twisted ribbo

8、n125 twists/inch (convolutions)The twists reverse in direction along the lengthCross-section: kidney-bean shaped with a lumenStructureSubmicrostructure5 distinctive regions:Cuticle: out layer of wax, a few molecules thick to protect seeds but can be removed by wet processing and laundering.Primary w

9、all: composed of fibrils: a sheath of spiraling fibrils 20 - 30 degree to the fiber axisMature fibers - thicker primary walls; immature fibers thinner primary walls and entangles: forming clumps called neps: leading to nonuniform dye properties and irregular surface of fabricsStructureSubmicrostruct

10、ure5 distinctive regions:Secondary wall: bulk of the fiberconcentric layer of spiraling fibrils similar to rings of trees20 rings and each corresponding to 1 days growth.outmost layer of secondary wall: winding layerLumen: hollow canal running through the length of the fiberStructurePolymer systemLi

11、near celluloseAverage Degree of Polymerization 6,000 to 10,000Functional side group: -OH Crystallinity: 65 - 70% but depends on how to define.H-bonding sites: not -OH to -OH but OH to the O group between the neighboring two rings: confers strength and additional rigidity to the fiber.-OH: reacting w

12、ith a variety of chemicals: thus finish can be applied easily, also attract and hold water.StructurePolymer system-C-O-C- bonds are more susceptible to oxidation than C-C-C bonds20 41% unoccupied space, 1/3 by lumenPropertiesMechanical PropertiesTenacity and initial modulus: mediumElongation at brea

13、k: low: spiral fibrils: makes it relatively brittleElastic recovery: low, only 75% at 2% extension: due to H-bondPropertiesComfortFiber ends and convolutions: comfortable to touchHydrophilic: max water absorption: 25-27% regain due to -OH group and fibrilsUpon water absorption, fibers become softer

14、and collapses on to skin, dries slowlyWhen it is dry: comfortable because of water absorption, water vapor transfer and no static chargePropertiesComfortWater resistant fabric possible: swelling of fibers in water: no liquid water penetrationMaintenanceSoiling: easy to be soiled and desoiled due to

15、-OH groupsLaunderability: dimensionally stable and tenacity increases when wet (10-20%) due to improvement of fibril orientation and thus molecular orientation.PropertiesMaintenanceNo special precautions for laundering, high temperature, any detergents, and bleaches can be used.Shrinkage likely due

16、to relaxation of yarn tension induced by processingPropertiesOther propertiesacids cause degradation of cotton or cellulose: acid free paper for long lasting itemsnot affected by most of organic solventsdamaged by fungi and bacteriaprolonged exposure to sunlight: yellowheat resistantlow lusterhigh c

17、over powerPropertiesOther propertiesno pill but linthighly flammable and can smolder without fire for hours: need flame-retardant treatment for many end usesbiodegradablecan be boiled and sterilized: good for hospital useMercerized cottonProcess:(applied to either fibers or yarns)cold bath of 18-27%

18、 NaOH for 1 minute or lessrinsed and neutralized by a cold acid bathtension applied to break H-bondspolymer rearranged and reoriented: untwistrounder cross-section and the convolutions are nearly goneStronger, more lustrous and easier to dye第一節(jié) 纖維素纖維（棉、麻、粘膠） 一、結(jié)構(gòu) 1.大分子結(jié)構(gòu)（1）化學(xué)組成 纖維素 （C、H、O組成）伴生物-棉：蠟質(zhì)

19、、糖份、果膠、灰分，占5%左右 麻：比棉含量要高（各種麻不同） 粘膠：無(wú)（2）單基 特征基團(tuán)：氧六環(huán)；6個(gè)-OH；氧橋-O- 單基連接方式：1-4甙鍵連接，在空間轉(zhuǎn)180,因?yàn)榇蠓肿觾?nèi)有氫鍵。（3）空間形態(tài)：椅式結(jié)構(gòu) 單基上的21個(gè)原子不在一個(gè)平面上。 1、3、5在下平面， 2、4、6在上平面；兩平面平行。 2. 超分子結(jié)構(gòu)大分子間作用力：強(qiáng)大的氫鍵力，還有范 德華力。結(jié)晶度：棉-60-70%左右；麻70%； 粘 膠-30-40% 取向度：棉-20-30；麻-7-8； 粘膠-看抽伸倍數(shù)，可人為控制，普通粘纖 30左右?？p隙空洞：棉-較小；粘纖-較大 3. 形態(tài)結(jié)構(gòu) 棉 ：腰圓形，有中腔，扁平帶

20、狀，有天然轉(zhuǎn)曲。 苧麻：腰圓形，有中腔裂縫。 粘膠：縱向有構(gòu)槽，截面呈鋸齒形，有皮芯層。 二. 性質(zhì)1.機(jī)械性質(zhì) 棉麻粘纖強(qiáng)度（g/d）3-4.9更高2.5-3.1 g/d濕強(qiáng)/干強(qiáng)1140-50%伸長(zhǎng)率3-7%較小16-22%初始模量較大最大較小2.吸濕染色性 20, 65%20, 100%公定W棉7-8%23-27%11.1%(紗線8.5%)苧麻7-8%12-14%粘纖13-15%29-35%13%3.耐酸堿性 與酸作用氧橋斷裂，氧化裂解； 與堿作用堿纖維素。4.其它 易燃燒，150分解； 棉、麻易霉； 5. 絲光棉 絲光通常是指棉織品（紗、布）在緊張狀態(tài)下經(jīng)濃堿液(NaOH或液氨)處理，

21、以獲得持久的光澤，并提高對(duì)染料吸附能力的加工過(guò)程。結(jié)構(gòu)變化：天然轉(zhuǎn)曲消失成為棒狀； 無(wú)定形區(qū)有所增加，結(jié)晶區(qū)有所下降； 取向度視張力變化而定。性能變化：光澤、染色性改善；強(qiáng)力增 大，延伸度下降；化學(xué)性能活潑。 第二節(jié) 天然蛋白質(zhì)纖維Wool Fibers MorphologyStructures of wool fibersSubmicrostructureCotexcore of the wool fiber: 90% of the fiber volume, consists of countless long, spindle-shaped cells held together by

22、intercellular cementWool fibers under polarized optical microscopeStructures of wool fibersSubmicrostructureCotexcan be divided into 2 sections: Orthocotex containing less cystine, and thus less S-S bondsParacortex containing more cystine, absorbing less water.two sections spiral around each other a

23、long the fiber length.the two sections respond to heat and moisture differently forming 3-D crimp.Structures of wool fibersSubmicrostructureCotex: each cortex cell composed ofmacrofibrilsmicrofibrilsprotofibrils - keratin polymer molecules (polypeptide)Structures of wool fibersKeratin polymer: helix

24、 of amino acidsStructural characteristics18 different amino acids: each with -N-C-C- backbonea helix: 3 amino acids per turn (right-handed helix)Diversity of amino acids: good for dyeingPolar groups in amino acids: hydrophilicityCystine amino acid: contains sulfur: degradation by moths and beetlesBi

25、g side groups and spiral molecular configuration: hard to be packed well leading to low crystallinity (only 25-30%)Structures of wool fibersIntermolecular bondingCross-linking: 2 cystine amino acids one on each of the two adjacent chains form a cystine link, a covalent bond (S-S bond), increasing st

26、rength and elasticity.Ionic bond: salt linkage formed when two amino acids are in close proximity: responsible for reacting with acid dyes.Hydrogen bonds: between amide groups but have relatively low density due to more amorphous phase and packing difficulties.Properties of wool fibersMechanical pro

27、perties:relatively low strength or tenacityhigh elastic recoveryhigh flexibilityhigh resiliencelow initial modulus low abrasion resistancelow stiffnesslow toughnessproperties change as water absorption changesProperties of wool fibersComfort properties:high heat of wetting due to more amorphous phas

28、e than many other fibers)slow the rate of evaporation of body waterwater repellent due to epicuticle3-D crimp traps more air reducing thermal conductivity air space 2/3 of total volume low luster due to crimp and scalesodor absorbenthigh pilling but easy to removeMaintenance of wool fibersSoil can b

29、e easily removed, but may absorb large quantities of oily soilWashing:wool fibers are weaker in water and have a lower modulus thus will be easily stretchedshrinks when agitated in water: felting shrinkagedegrades in mild alkaline solutions, e.g. detergent solutions because alkalinity weakens salt &

30、 cystine linkages and increase felting: dry cleaning recommendedMaintenance of wool fibersWashing:Bleaches degrades wool and should not be used.Dry heat makes fiber brittleRelatively high resistance to acidDecomposition due to bacteria & enzymes, moths and beetles harm wool esp. when stained: moth b

31、alls and cedar chests recommendedLow flammability: self-extinguishes due to high water content (need high energy to get rid of water)chemical absorption: easily absorbs large amount of oil: good for remove oil spillage or toxic chemicals. Production of wool fibers55% produced in Australia, former US

32、SR and New Zealandclipped wool or fleece wool: sheared from the sheep (annually done early spring), better qualitypulled wool: pulled from hide.chemically shed: falling off in 2 weeks of feeding the chemical to the sheepscoured: remove wool grease, suint, sand and some plant materials (could be 50%

33、of the raw wool)Lanolin in grease: good for making pharmaceutical or cosmetic productsStructure of woolMolecular structureHydrogen bondAmino AcidsCystine bondTensile behavior of natural fibersSilk Fibers IntroductionThe larva of certain insects for use in their building webs, climbing ropes and coco

34、onsSpiders Commercial silk industry: use larva of silkwormApplication: Mostly apparel, was also used for parachutes.StructureMacrostructure:Length: 1000-1300 yds (915-1190 m)/cocoon Max 3000yds (2750m)/cocoon, 1 fiber/cocoon.Thickness: 9-11 mm or 1.2-1.5 denier.Varies: thickest in the middle thinnes

35、t inside (maybe running out of raw material, or maybe just make itself comfortable).StructureMicrostructurecross-section: 2 triangular filaments co-extruded by a worm. The two are called brins held together by sericin (gum or silk glue).Wild silk worms produce ribbon-like silk fibersStructureSubmicr

36、ostructureSilk from cultivated worm: no identifiable submicrostructure.Wild silk or Tussah silk has internal fibrillar structure.StructureFibroin protein polymerA chain of amino acids forming a protein called fibroin composed of 15-18 different amino acids.Glycine, alanine and serine occupy 86% of t

37、he polymerThe side groups of the above 3 amino acids are small compared with those in wool:glycine: R = Halanine: R = -CH3Serine: R = -CH2OHCrystallize readily: 70-75% StructureFibroin protein polymerPack well: lots of H-bonds, small number of ionic bondsNo cystine: no S-S bondsConfiguration: pleate

38、d b-sheetDegree of polymerization of silk DPsilk DPwoolPropertiesFor silk producers, i.e. silk worm, spider etc., silk fibers are for protection, transport and food captureMechanical propertiesMedium tenacity but higher than woolresulted from molecular structure: zigzag b-sheet of silk vs a-helix of

39、 wool extruded instead of grown as a cellhigher crystallinity than woolPropertiesMechanical propertiesMedium elongation at breakHigh elastic recovery at low elongationWhen elongated 2%, 90% elastic recovery Medium modulusMedium abrasion resistanceMedium resilience: (cotton silk wool) pleated sheets

40、can slide over one-another.PropertiesComfortHigh heat of wetting: lots of polar groups availableHigh water absorption: up to 1/3 of its weightSmooth and softHigh luster: high crystallinity and triangular cross-sectional shape.Scroop: rustling sound due to an acid treatment that hardens fiber surface

41、.PropertiesOther propertiesIgnites and burns but sometimes selfextinguishingDry-cleaning preferred due to:lower tenacity and initial modulus when wetdegraded by alkaline solutionsmay be hand-washed using mild detergentsLowest UV light resistance: avoid prolonged exposure to sunshineProductionMoth: B

42、ombyx fed on mulberry tree leavesWorld production: 70 million kg/yrOriginally from ChinaTypes: Raw silk: silk with gumTussah: wild silkDuppioni: 2 silk worm spin their cocoons together: having special appearance similar to wild silk but better color第二節(jié) 天然蛋白質(zhì)纖維一. 結(jié)構(gòu) 1. 大分子結(jié)構(gòu) （1）化學(xué)組成羊毛：蛋白質(zhì)角朊；C、H、O、N、S

43、元素組成。絲 ：蛋白質(zhì)絲素（70-80%），少量絲膠（20-30%）；C、H、O、N元素組成。 柞蠶絲：絲素85%（2）單基R側(cè)基羊毛：多、復(fù)雜，約25種氨基酸； 蠶絲：少、簡(jiǎn)單，約18種氨基酸。 （3）空間形態(tài)： 羊毛的穩(wěn)定結(jié)構(gòu)是型，型加外力變?yōu)樾?，型去外力變?yōu)樾停恍Q絲的穩(wěn)定結(jié)構(gòu)是型。 2. 超分子結(jié)構(gòu) 分子間力 羊毛：范德華力、鹽式鍵、氫鍵、硫鍵力； 蠶絲：范德華力、鹽式鍵、氫鍵結(jié)晶、取向 羊毛的結(jié)晶度、取向度低，而蠶絲的較大。 3. 形態(tài)結(jié)構(gòu)： 羊毛鱗片層、皮質(zhì)層、髓質(zhì)層 1)鱗片層：作用如下： 保護(hù)纖維，使羊毛內(nèi)層組織不受外界的生物、 化學(xué)、機(jī)械等作用；由于鱗片具有方向性，形成差微摩擦

44、效應(yīng)。鱗片形狀： 環(huán)狀、瓦狀、龜裂狀 2)皮質(zhì)層：羊毛纖維的主體，占90%左右。 皮質(zhì)細(xì)胞：正皮質(zhì)結(jié)構(gòu)疏松； 偏皮質(zhì)（副皮質(zhì)）結(jié)構(gòu)緊密； 雙邊結(jié)構(gòu)：細(xì)羊毛的正副皮質(zhì)細(xì)胞（結(jié)構(gòu)與性能不同）分布于纖維的兩側(cè)，并在長(zhǎng)度方向上不斷轉(zhuǎn)換位置，正皮質(zhì)一般在纖維卷曲處的外側(cè)，而副皮質(zhì)處于卷曲的內(nèi)側(cè)，使羊毛具有天然卷曲。這種結(jié)構(gòu)成之。 3)髓質(zhì)層存在于粗羊毛中；羊毛越粗，中腔髓質(zhì)層的比例越大，羊毛品質(zhì)越低。 蠶絲：絲素外包有絲膠； 縱向平滑，截面為不規(guī)則三角形。 2. 性質(zhì) 羊毛蠶絲強(qiáng)度小較大伸長(zhǎng)較大（25-35%）較小（1525%）初始模量小較大彈性好較差吸濕性好（15%）較好（11%）耐熱性較差耐微生物性

45、耐霉不耐蛀化學(xué)性質(zhì)耐酸不耐堿（蠶絲比羊毛稍差）比重（g/cm3）1.321.331.45特性縮絨性光澤、懸垂性、絲鳴 縮絨性 羊毛在濕熱及化學(xué)試劑作用下，經(jīng)機(jī)械外力反復(fù)擠壓，纖維集合體逐漸收縮緊密，并相互穿插，糾纏，交編氈化。這一性能稱之。利：縮絨使毛織物有獨(dú)特的風(fēng)格； 弊：縮絨使毛織物的尺寸穩(wěn)定性變差（洗滌后易收縮，變形）影響穿著的舒適性與美觀（起毛起球） 第三節(jié)常用化學(xué)纖維Rayon IntroductionRayon: ray of light onInvented 1884Definition: manufactured fibers composed of 100% regenera

46、ted cellulose, as well as manufactured fibers of regenerated cellulose in which substituents have replaced not more than 15% of the hydrogens of the -OH groups.IntroductionMade from 4 processes:Nitro cellulose: made in U.S. during 20s-40s and easy to explode.Viscose: 95% today spun in U.S.Cuprammoni

47、um: use cuprammonium hydroxide solvent as spinning solutionLyocell Introduction wrinkle freeCan be laundered but not easy to cleanVulnerable to degradation in acidslow resistance to sunlightmelts and drips Polyester Fibers IntroductionManufactured fibers in which fiber forming substance is any long-

48、chain polymer composed of at least 85% by weight of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic unitsGeneric group members:PET (polyethylene terephthalate) 95%IntroductionPCDT: poly(1,4-cyclohexylene dimethylene), Eastman KodakPEB: poly(ehtylene o

49、xybenzoate), produced in Japan, 70s and 80sPTT: poly(trimethylene terephthalate)PBT: poly(butylene terephthalate)Polymerization reactionsStep growth or condensation polymerizationStructureMolecular structuresStructureSmooth, even diameterdiameter generally 12-25 mmwhite or off-white colorsIntermolec

50、ular forces:dipole-dipole between benzene ringsLinear polymer: DP 115-140Crystallinity: 35%Orientation: very well oriented PropertiesPETHigh tenacity due to high orientationHigh failure elongationElastic recovery High with low stress: 97% at 2% strain. Low with high stress because dipole-dipole bond

51、ing is not strong enough to hold, leading to intermolecular slippageLow compressional resilience: not good for carpet fiberPropertiesVery low moisture regainLow level of wicking due to hydrophobic surfaceHigh electrical resistivity: static charge likely at low humidityMedium specific gravityPillingH

52、igh dimensional stabilityHigh Tm 265C for PET PropertiesResistant to acids, potentially degrades in concentrated alkaliesNo UV degradationFlammable with black smokeMelt dripBest thermal resistance among all general use syntheticsProductionPolymerizationForm chipsmelt spinningdrawingheat setting to i

53、ncrease crystallinity and orientation, reduce elongation and shrinkageModificationHigh tenacity for tire cord (higher DP and crystallinity)WickingSheath-core: polyester core, low melt polymer sheathDu Pont Coolmax: 20% more surface area and maybe hydrophilic treated for wickingDupont Thermax: hollow

54、 fibers: excellent thermal insulation and 20% weight reductionPTT fiber（彈性纖維）Polytrimethylene terephthalate（聚對(duì)苯二甲酸丙二醇酯） Condensation polymerization of 1,3-propanediol (PDO) and terephthalic acid Chemical structureConfigurationPTTPETPTT fiber propertiesPropertiesStress-strain curve of PTTElastic reco

55、very of PTTPTT fiber propertiesPTT fiber productsCarpet (as a substitute for nylon)Textiles (in the high value market as a substitute for nylon and polyester)Engineering thermoplastics From /sorona/home.htmlPTT polymer producersPTT Polymer Invented in 1941Commercialized in recent years byShell Chemi

56、cal: Corterra polymer through petrochemical route to 1,3-PDODuPont: Sorona polymer through biotech (corn) route to 1,3-PDOOlefin Fibers烯烴纖維 IntroductionPolypropylene and polyethylene or copolymer of ethylene and propyleneEnd uses:52% used in carpets and rugs4% interior textile products43% industrial

57、 and consumer products0.5% apparelPolymerizationAddition or chain growth polymerization from ethylene or propyleneStructuresIntermolecular forces:Van der WaalsCrystallinity: 50-65%Composed of fibrilsPropertiesTenacity: highlinear molecules: easy to orientElongation: medium but depends on orientation

58、Elastic recovery: highAbrasion resistance: high due to slick surface or low surface energyFlammability: low due to meltingPropertiesToughness (work of rupture): highInitial modulus: depends on orientation, in general mediumMoisture absorption: noneMelting and glass transition temperaturePE Tm = 130C

59、, Tg = -120 CPP Tm = 170C, Tg = -10 CSpecific density: 0.9 - 0.92Acrylic Fibers腈綸纖維 IntroductionInvented in conceptually in 1893Produced initially in 1944 and full scale in 1950End uses:75% in apparel18% household 7% Industrial and consumer textiles PolymerizationAddition or chain growthHomopolymer:

60、 polyarylonitrile strong but compact and highly orientedvirtually impossible to dyeCopolymers: other types of monomers are included for a dyeable fiber and easier to process: e.g. acrylic acid and vinylpyrrolidonemost acrylic fibers are copolymersStructureMicroscopiccross-section: dog-bone shapedkid