专外-专业外语chapter14fiber identification

Joseph’sIntroductory

TextileScience(6thEd.)XudongYang杨旭东

Ch.14FiberIdentificationWordslistKeywords全部Newwords1，3，4，7，10，11，15，17，18，24，25，29，30，33，39，42，49，50，57，58，77，78，81，87。Table14.11，8，10，11，19-21。Consumersusuallycouldidentifythefibercompositionoffabricsmadeof100percentrayonoracetate,blendsofsomefibersweredifficulttoidentify.Asmorefiberswereintroduced,thetaskbecameprogressivelymoredifficult.Today,sophisticated(复杂的，高级的)techniquesareusuallyrequiredforaccuratefiberidentification.

Formostindividuals,theonlyinformationneededisaqualitativeanalysisoffibercontent:whatfiberorfibersarepresentinthisproduct?Forothers,aquantitativeanalysisoftheproductisalsoimportant:inwhatpercentagesarethefiberspresent?Withthenumbersoffibersavailabletodayandthevarietyofblendsbeingproduced,neitheranalysisiseasy.Methodsforqualitativeidentificationoffibersincludesuchproceduresasburningtests,microscopy,densitydetermination,moistureregainanalysis,dyestaining,chemicalsolubility,meltingpointdetermination,infraredspectroscopy(红外光谱学),andchromatography（色层分离法）.Simplifiedversionsofthefirstsixproceduresarerelativelyeasytoperforminmostlaboratories.Theyrequiretheuseofadryingoven,onanalyticalbalance分析天平

sensitiveto.005gram,acompoundlightmicroscope（复显微镜）capableof200×magnification,laboratoryglassware（玻璃器皿）,andasupplyofchemicals.Thefirstsectionofthischapterdescribesthesimpleproceduresforfiberidentificationandincludescharts(图，图表)andphotographsthataidininterpretingthedatacollected.Thesecondsectiondiscussesthesignificanceofsomeoftheotherfiberidentificationprocedures.如何在科技文献的开头（Introduction）的最后一段表述整篇文章的组织方式。SimpleFiberIdentification-BurningTestTheburningtestisagoodpreliminarytestforcategorizingfibers.Observationofburningprovidesinformationonbehaviorinaflame,smokegeneration,odorduringburning,andashorresidue.Itnevershouldbeusedastheonlymethodofidentifyingafiber,butitprovidesvaluableinformationthatmaybeusedwithotherevidencetomakeapositive（确定的）identificationofanunknownfiber.BurningTestProcedureThesampletobetestedshouldbeinfiberform.Asingleyarnfromawovenorknittedfabricshouldbeuntwistedtoproduceatuft(毛撮，簇绒)offibersfortesting.Usethefollowinginstructions,andobservethereactionsoftheburningfiberverycarefully.Step1:Holdthetuftoffiberswithapairoftweezers.Step2:Movethetuftclosetothesideoftheflame,donotplacethefibersaboveorbelowtheflame.Observecarefullytoseeifthefibersmelt,shrink,ordrawaway（离开）fromtheflame.Step3:Slowlymovethefibertuftintotheflametoobserveitsburningbehavior,andthenslowlyandcarefullyremovethetuftfromtheflametoobservethereactiononceflamesourceisnolongerpresent.Carefulobservationprovidesananswertothesefourquestions:(a)Whenintroducedtotheflame,doesthefiberburnrapidlyordoesitshownosignofignition（点燃）?(b)Doesthematerialbegintomelt?(c)Doesthematerialproduceasputtering（飞溅、爆裂）flame,asteadyflame,ornoflameatall?(d)Whenthefiberisremovedfromtheflame,doesitcontinuetoburnordoesitself-extinguish?Step4:Ifthematerialisstillburningwhenitisremovedfromtheflame,blowout（吹熄）theflame.

Notetheodorandcolorofthesmoke,or

notethatnosmokewasproducedwhenthe

fiberwasremovedfromtheflame.Step5:Observetheresidueremainingafterburning.Doesaresiduedropfromthetweezers?Doesthatresiduecontinuetoburn?Howmuchresidueisleft?Doestheresidueremainred,indicatingthatitisstillveryhot?Whatcoloristheashthatremains?Istheashtheshapeofthefiberlightandfluffy,orisitbead-shaped（小串珠状，小球状）?Step6:Afteritcoolsoff,touchtheresidueorash.Is

itsoftorbrittle?Canitbecrushedeasily

betweenthefingers,orisithardtocrush?RESULTSItisdifficulttodetectthepresenceofblends

withaburningtest.Onefiberinablendmay

completelymaskthepropertiesofanotherfiber.Dyesandfinishesaffecttestresults.Flame-

retardantfinishes（阻燃整理）

areespeciallymisleading（误导）.Coloredfibers,especiallythoseproducedwithpigments,mayretainthecolorintheashorresidue.LIGHTMICROSCOPYAcompoundmicroscopecapableofatleast200xmagnificationisrequiredforfiberidentification.Amagnificationof100xmaybeadequatefortentative（试验性的，假设的）identification,especiallyofthenaturalfibers,butisnotadequateforviewingthedetailsoffiberstructure.Amicroscopewithbothlow-powerandhigh-powerobjectives(目标、对象、物镜)(usually10×and20×)anda10×eyepiece（目镜）

issatisfactory.Itislessdifficultforanovice（新手，初学者）tolocateasinglefiberat100×magnificationandthenchangetheobjectivetoprovidethe200×magnificationthanitistolocateasinglefiberat200×.Longitudinalmounts（载片）offibersareeasytomake.Withalittlepractice,crosssectionsusingacork（软木）asamountingmediumareeasytoproduce.Thelens（透镜，镜片，镜头）

andobjectivesofthemicroscope,aswellastheslides（载玻片）

andcoverglasses.（盖玻片)mustbecleanandfreeofscratches.Thelightsourceshouldbeadjustedformaximumvisibilitypriortolookingatpreparedslides.

Havematerialsathandtosketch(草图、概略)thefibersviewedandhaveaccesstoasourceofphotographsofknownfiberstomakecomparisonsforidentification.Figure14.2(pp.142-46)showsthelongitudinalandcross-sectionalviewsofthemostcommonfibers.LongitudinalMountsItispossibletomountasinglefiber,butitislessfrustrating（挫败）formostmicroscopiststouseseveralfibers.Aminimumof10fibersisusefulwhenthematerialtobestudiedisablend.Toomanyfibersonaslidemakesitdifficulttofocusonasinglefibertoobservethedetailsofitssurfacecontour.Whentakingasamplefromayarninafabric,untwisttheyamcompletelytoseparatethefibers.Thebasicstepsformakingalongitudinalmountareasfollows.（如何表述做某个试验时的步骤之前的开头语“步骤如下”）1.Placeasingledropofwater,glycerine（甘油）,ormineraloilonthecenteroftheglassslide.Mineraloilprovidesthebestdefinition（清晰度、精确度）,buttheothermaterialsareadequate2.Carefullyplacethefibersinthedropof

liquidwiththelengthofthefibersparallelto

thelongdimensionoftheslide.3.Placethecoverglasslightlyoverthedropof

liquidandthespecimen.Tap（轻打）thecoverglassgentlytoremoveairbubbles.4.Withtheobjectiveinitshighestposition,placetheslideonthestage（载物台）ofthemicro-scope.Lowertheobjectivecarefullybeforetryingtofocustheslide.Itisveryeasytodamagetheobjectivebyscratching（刮、擦）itorsmearing（涂抹、污点）itwithoil.5.Focusonlowpowerandobservethefiberbeforefocusingonhighpower.Notethegeneralshapeofthefiber,thenlookatitcarefullyforsignsofscales（鳞片）,convolutions（卷曲）,pockmarks（斑点）,striations(条痕，条纹),andotherfeatures.Lookcarefullytoseeifmorethanonetypeoffiberispresent.6.Withthemicroscopefocusedonhighpower,movethefineadjustment（微调）veryslowlytoseeifvariationsinsurfacecontour（轮廓）arevisible.Again,lookcarefullytoseeifmorethanonefibertypeispresent,7.Sketchthefibersasseenthroughthemicroscope,thencompareyoursketchwithstandardphotographstoconcludewhichfibersmightbepresent.Cross-sectionalMounts

Specialplasticandmetalplatesareavailableformakingfibercrosssections(Figure14.3).Specialfibermicrotomes(切片机，切片刀)areusedformoresophisticatedwork.Wheresuchaidsarenotavailableitispossibletomakeasectionusingapieceofcork,athreadedsewingmachineneedle,andasharpsingle-edge（刀口）razor（剃刀）blade(Figure14.4).Theinstructionsfollow.1.Useasmallpieceoffine-grain（成细颗粒的）corknomorethan1cm(0,5in.)thick.Cutsothatitisflatononeside.Thecorkwedge（楔）shouldbeofadiametersmallenoughtosliceeasily.2.Threadthesewingmachineneedle,andcarefullyforcethepointoftheneedlethroughthecorkuntilaloopofthreadcanbeformed(Figure14.5).3.Formathreadlooparoundyourfingerandpulltheneedlebackthroughthecork(Figure14.6).Theneedlemaythenberemoved;itwasneededjusttopushthethreadthroughthecorktoformtheloop.4.Makeasmallbundleoffibertofitthroughthethreadloop.Then,usingthefreeendsofthethread,carefullypulltheloopedfiberbackthroughthecork.Thefibershouldbepackedfirmlyintheholeofthecork,andfiberendswillbevisibleonbothsidesofthecork(Figure14.7).Afteralittlepracticeestimationoftheexactamountoffibertouseeseasier.5. Placetheflatsideofthecorkdownonacuttingboardandusetherazorbladetocutathinsliceperpendicular（垂直的）tothefiberembeddedinthecork.Thesliceshouldbenomorethan0.5mmthick.Makethecutwithasingle,continuousmotion,notasawing（锯）motion.6. Placethecorksliceonaglassslide.Donotuseamountingmediumorcoverglass.Focusthemicroscopeandobservethecrosssectionsofthefibers.CHEMICALSOLUBIUTYTESTSWhensolventsareusedatroomtemperature,thetestsmaybeperformedinawatchcrystal（表面皿）,a50-mlbeaker(烧杯).orasmalltesttube.Placeasmallamountofthefiberinthecontainerandaddthesolvent.Useabout1mlofsolventfor10mgoffiber.WatchcrystalMICROSCOPYOTHERTHANLIGHTSeveraltypesofmicroscopyotherthanlightmicroscopyareveryhelpfulinidentifyingfibers.Thepolarizing（偏光）microscopeisusedfrequently,andlaboratorieswithelectronmicroscopesfindthemusefulforinspectingfibersatveryhighmagnifications.Acousticalmicroscopeshavebeenusedinsomelaboratories.butwithlimitedbenefit.Smallvideounitswithacamera,amonitor,andacomputerarebeingusedtoscreen（拍摄、鉴别）textilesamples(Figure:14.8)Suchsystemshaveseveraladvantages.Themostobviousisthatmultipleindividualscansimultaneouslyviewasampleunderthemicroscope.Itiseasiertodiscussapictureonascreenthanatinyimage.Thezoomlens（镜头）inmanyofthecamerasallowsawiderangeofmagnifications.andthespecimencanbemovedabouttoallowallthosepresenttoscantheimage.Imagescanbestoredonvideofilmforfuturereference.TheunitshowninFigure14.8isawide-field（宽扫描场的）stereomicroscope(体视显微镜)forviewingfabrics,butitisquitesimpletomountacameraunitintheeyepiece（目镜）ofanylightmicroscope.PolarizingMicroscope(偏光显微镜)Apolarizingmicroscopeprovidesinformationonthechemicalstructureofafiberaswellasthephysicalstructure.Itisusedtodeterminetherefractiveindex（折射率）,birefringence（双折射）,andpolarizationcolors（偏振光颜色）ofafiber.Becausepolarizedlightmicroscopyisanondestructivetest—thatis,thesampleisnotdestroyedbythetesting—itispreferredbyforensic

（法院的）scientistswhowishtopreserveallevidence.Apolarizingmicroscopeisalightmicroscopethathasapolarizingfilm,calledapolarizer（偏光镜、起偏镜）,mountedbelowthesubstage（台下、辅台）condenser（聚光镜）.Thepolarizerisgenerallysetinthe“north-south”positiontoorient（定向）thedirectionofvibration（振动）ofthelight.Anotherpolarizingfilm,calledananalyzer(检偏振器),ismountedinthe“east-west”position.Whenthepolarizerandtheanalyzer,bothcalledpolars(极线，极面),arecrossedatrightangles,themicroscopicfieldisdark.Polarizationcolorscanbeviewedbyinsertingspecialfilters（滤光片）,suchasafirst-orderredplate（一级红晶片）,in