專外-專業(yè)外語chapter14fiber identification

Joseph’sIntroductory

TextileScience(6thEd.)XudongYang楊旭東

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(復(fù)雜的，高級(jí)的)techniquesareusuallyrequiredforaccuratefiberidentification.

Formostindividuals,theonlyinformationneededisaqualitativeanalysisoffibercontent:whatfiberorfibersarepresentinthisproduct?Forothers,aquantitativeanalysisoftheproductisalsoimportant:inwhatpercentagesarethefiberspresent?Withthenumbersoffibersavailabletodayandthevarietyofblendsbeingproduced,neitheranalysisiseasy.Methodsforqualitativeidentificationoffibersincludesuchproceduresasburningtests,microscopy,densitydetermination,moistureregainanalysis,dyestaining,chemicalsolubility,meltingpointdetermination,infraredspectroscopy(紅外光譜學(xué)),andchromatography（色層分離法）.Simplifiedversionsofthefirstsixproceduresarerelativelyeasytoperforminmostlaboratories.Theyrequiretheuseofadryingoven,onanalyticalbalance分析天平

sensitiveto.005gram,acompoundlightmicroscope（復(fù)顯微鏡）capableof200×magnification,laboratoryglassware（玻璃器皿）,andasupplyofchemicals.Thefirstsectionofthischapterdescribesthesimpleproceduresforfiberidentificationandincludescharts(圖，圖表)andphotographsthataidininterpretingthedatacollected.Thesecondsectiondiscussesthesignificanceofsomeoftheotherfiberidentificationprocedures.如何在科技文獻(xiàn)的開頭（Introduction）的最后一段表述整篇文章的組織方式。SimpleFiberIdentification-BurningTestTheburningtestisagoodpreliminarytestforcategorizingfibers.Observationofburningprovidesinformationonbehaviorinaflame,smokegeneration,odorduringburning,andashorresidue.Itnevershouldbeusedastheonlymethodofidentifyingafiber,butitprovidesvaluableinformationthatmaybeusedwithotherevidencetomakeapositive（確定的）identificationofanunknownfiber.BurningTestProcedureThesampletobetestedshouldbeinfiberform.Asingleyarnfromawovenorknittedfabricshouldbeuntwistedtoproduceatuft(毛撮，簇絨)offibersfortesting.Usethefollowinginstructions,andobservethereactionsoftheburningfiberverycarefully.Step1:Holdthetuftoffiberswithapairoftweezers.Step2:Movethetuftclosetothesideoftheflame,donotplacethefibersaboveorbelowtheflame.Observecarefullytoseeifthefibersmelt,shrink,ordrawaway（離開）fromtheflame.Step3:Slowlymovethefibertuftintotheflametoobserveitsburningbehavior,andthenslowlyandcarefullyremovethetuftfromtheflametoobservethereactiononceflamesourceisnolongerpresent.Carefulobservationprovidesananswertothesefourquestions:(a)Whenintroducedtotheflame,doesthefiberburnrapidlyordoesitshownosignofignition（點(diǎn)燃）?(b)Doesthematerialbegintomelt?(c)Doesthematerialproduceasputtering（飛濺、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（小串珠狀，小球狀）?Step6:Afteritcoolsoff,touchtheresidueorash.Is

itsoftorbrittle?Canitbecrushedeasily

betweenthefingers,orisithardtocrush?RESULTSItisdifficulttodetectthepresenceofblends

withaburningtest.Onefiberinablendmay

completelymaskthepropertiesofanotherfiber.Dyesandfinishesaffecttestresults.Flame-

retardantfinishes（阻燃整理）

areespeciallymisleading（誤導(dǎo)）.Coloredfibers,especiallythoseproducedwithpigments,mayretainthecolorintheashorresidue.LIGHTMICROSCOPYAcompoundmicroscopecapableofatleast200xmagnificationisrequiredforfiberidentification.Amagnificationof100xmaybeadequatefortentative（試驗(yàn)性的，假設(shè)的）identification,especiallyofthenaturalfibers,butisnotadequateforviewingthedetailsoffiberstructure.Amicroscopewithbothlow-powerandhigh-powerobjectives(目標(biāo)、對(duì)象、物鏡)(usually10×and20×)anda10×eyepiece（目鏡）

issatisfactory.Itislessdifficultforanovice（新手，初學(xué)者）tolocateasinglefiberat100×magnificationandthenchangetheobjectivetoprovidethe200×magnificationthanitistolocateasinglefiberat200×.Longitudinalmounts（載片）offibersareeasytomake.Withalittlepractice,crosssectionsusingacork（軟木）asamountingmediumareeasytoproduce.Thelens（透鏡，鏡片，鏡頭）

andobjectivesofthemicroscope,aswellastheslides（載玻片）

andcoverglasses.（蓋玻片)mustbecleanandfreeofscratches.Thelightsourceshouldbeadjustedformaximumvisibilitypriortolookingatpreparedslides.

Havematerialsathandtosketch(草圖、概略)thefibersviewedandhaveaccesstoasourceofphotographsofknownfiberstomakecomparisonsforidentification.Figure14.2(pp.142-46)showsthelongitudinalandcross-sectionalviewsofthemostcommonfibers.LongitudinalMountsItispossibletomountasinglefiber,butitislessfrustrating（挫?。ゝormostmicroscopiststouseseveralfibers.Aminimumof10fibersisusefulwhenthematerialtobestudiedisablend.Toomanyfibersonaslidemakesitdifficulttofocusonasinglefibertoobservethedetailsofitssurfacecontour.Whentakingasamplefromayarninafabric,untwisttheyamcompletelytoseparatethefibers.Thebasicstepsformakingalongitudinalmountareasfollows.（如何表述做某個(gè)試驗(yàn)時(shí)的步驟之前的開頭語“步驟如下”）1.Placeasingledropofwater,glycerine（甘油）,ormineraloilonthecenteroftheglassslide.Mineraloilprovidesthebestdefinition（清晰度、精確度）,buttheothermaterialsareadequate2.Carefullyplacethefibersinthedropof

liquidwiththelengthofthefibersparallelto

thelongdimensionoftheslide.3.Placethecoverglasslightlyoverthedropof

liquidandthespecimen.Tap（輕打）thecoverglassgentlytoremoveairbubbles.4.Withtheobjectiveinitshighestposition,placetheslideonthestage（載物臺(tái)）ofthemicro-scope.Lowertheobjectivecarefullybeforetryingtofocustheslide.Itisveryeasytodamagetheobjectivebyscratching（刮、擦）itorsmearing（涂抹、污點(diǎn)）itwithoil.5.Focusonlowpowerandobservethefiberbeforefocusingonhighpower.Notethegeneralshapeofthefiber,thenlookatitcarefullyforsignsofscales（鱗片）,convolutions（卷曲）,pockmarks（斑點(diǎn)）,striations(條痕，條紋),andotherfeatures.Lookcarefullytoseeifmorethanonetypeoffiberispresent.6.Withthemicroscopefocusedonhighpower,movethefineadjustment（微調(diào)）veryslowlytoseeifvariationsinsurfacecontour（輪廓）arevisible.Again,lookcarefullytoseeifmorethanonefibertypeispresent,7.Sketchthefibersasseenthroughthemicroscope,thencompareyoursketchwithstandardphotographstoconcludewhichfibersmightbepresent.Cross-sectionalMounts

Specialplasticandmetalplatesareavailableformakingfibercrosssections(Figure14.3).Specialfibermicrotomes(切片機(jī)，切片刀)areusedformoresophisticatedwork.Wheresuchaidsarenotavailableitispossibletomakeasectionusingapieceofcork,athreadedsewingmachineneedle,andasharpsingle-edge（刀口）razor（剃刀）blade(Figure14.4).Theinstructionsfollow.1.Useasmallpieceoffine-grain（成細(xì)顆粒的）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（鋸）motion.6. Placethecorksliceonaglassslide.Donotuseamountingmediumorcoverglass.Focusthemicroscopeandobservethecrosssectionsofthefibers.CHEMICALSOLUBIUTYTESTSWhensolventsareusedatroomtemperature,thetestsmaybeperformedinawatchcrystal（表面皿）,a50-mlbeaker(燒杯).orasmalltesttube.Placeasmallamountofthefiberinthecontainerandaddthesolvent.Useabout1mlofsolventfor10mgoffiber.WatchcrystalMICROSCOPYOTHERTHANLIGHTSeveraltypesofmicroscopyotherthanlightmicroscopyareveryhelpfulinidentifyingfibers.Thepolarizing（偏光）microscopeisusedfrequently,andlaboratorieswithelectronmicroscopesfindthemusefulforinspectingfibersatveryhighmagnifications.Acousticalmicroscopeshavebeenusedinsomelaboratories.butwithlimitedbenefit.Smallvideounitswithacamera,amonitor,andacomputerarebeingusedtoscreen（拍攝、鑒別）textilesamples(Figure:14.8)Suchsystemshaveseveraladvantages.Themostobviousisthatmultipleindividualscansimultaneouslyviewasampleunderthemicroscope.Itiseasiertodiscussapictureonascreenthanatinyimage.Thezoomlens（鏡頭）inmanyofthecamerasallowsawiderangeofmagnifications.andthespecimencanbemovedabouttoallowallthosepresenttoscantheimage.Imagescanbestoredonvideofilmforfuturereference.TheunitshowninFigure14.8isawide-field（寬掃描場的）stereomicroscope(體視顯微鏡)forviewingfabrics,butitisquitesimpletomountacameraunitintheeyepiece（目鏡）ofanylightmicroscope.PolarizingMicroscope(偏光顯微鏡)Apolarizingmicroscopeprovidesinformationonthechemicalstructureofafiberaswellasthephysicalstructure.Itisusedtodeterminetherefractiveindex（折射率）,birefringence（雙折射）,andpolarizationcolors（偏振光顏色）ofafiber.Becausepolarizedlightmicroscopyisanondestructivetest—thatis,thesampleisnotdestroyedbythetesting—itispreferredbyforensic

（法院的）scientistswhowishtopreserveallevidence.Apolarizingmicroscopeisalightmicroscopethathasapolarizingfilm,calledapolarizer（偏光鏡、起偏鏡）,mountedbelowthesubstage（臺(tái)下、輔臺(tái)）condenser（聚光鏡）.Thepolarizerisgenerallysetinthe“north-south”positiontoorient（定向）thedirectionofvibration（振動(dòng)）ofthelight.Anotherpolarizingfilm,calledananalyzer(檢偏振器),ismountedinthe“east-west”position.Whenthepolarizerandtheanalyzer,bothcalledpolars(極線，極面),arecrossedatrightangles,themicroscopicfieldisdark.Polarizationcolorscanbeviewedbyinsertingspecialfilters（濾光片）,suchasafirst-orderredplate（一級(jí)紅晶片）,in