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Viscose Blended Fabric

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Viscose Blended FabricViscos

    Viscose Blended Fabric JournalofDonghuaUniversity(Eng.Ed.)9'o1.26,No.6(2009)651 ResearchonThermalPropertiesofNomexFiberandNomex/Viscose BlendedFabric

    GENGWei(耿伟),ZHAOShu-lin(赵书林)

    SchoolofTextiles.TianjinPolytechnicUniversity.Tianjn30016O?China

    Abstract:BasedontheanalysisofthepropertiesofNomex 450andNomex462.thethermalpropertiesofNomex462/ LenzingViscoseF1aineretardent(FR)blendingmaterials wereanalyzed.ItwasdiscoveredthroughbIlrIIj_Ilgtestand ThermalGravity(TG)analysisthattheblendedmaterial wassuperiorinthermalbehaviorstothematerialmadefrom eitherNomexorViscoseFRfilament.whentheratioof NomexandLenzingViscoseFRreached80:20,and

    excellentthermalpropertieswereachievedwiththevalueof LimitingOxygenIndex(LOI)upt036.1%.Blending NomexandViscoseF=Rfilamentsmayberecommendedfor betterfireretardantpropertyofrelatedfabric. Keywords:Nomexfiber;LenzingViscoseVLa?pieretardent (FR)fiber;ThermalGravity(G)analysis;blending

    material;flan~-retardant

    cLCnumber:TS104.73Documentcede:A

    Article119:1672522O(2OO9)O6065105

    ntroduction

    Nowtheapplicationfieldofthehotprotectivefabric becomeswiderandwider.Thehotprotectivefabric's functionismainlytoprotectthehumanbodyfromvarious

    injuriesarisenbyhot,suchastheconductionhot,the radiationhot,thesplashofmeltedmetal,andthehot steamorair.Recently,inAmerica.Canada,Japan,and manyEuropecountries,thehotprotectivefabricmade fromthefire.resistantfibersuchasAramidfibers(P, PMIA,andPI),arewidelyusedintheareasofthe nationaldefence,thefireprotection,andthemetallurgy. Ithasbeenreportedthatthehotprotectivefabricmade fromNomexIIIAandLenzingViSCOSCF1alrleretardent (FR)areusedinmanyareasofAmericaandCanada.In thispaper.theNomex462andLenzingViscoseFRfibers wereusedfirstlytodevelopthehotprotectivefabricswith differentblendrates.Andthefire.resistantpropertyof thesefabricswasstudied.

    1Experimental

    Thetestingfiberswere:

    (1)Nomex450norm:2.22dtex×51mm(DuPont);

    (2)Nomex462norm:1.67dtex×51mm(DuP0nt);

    (3)LenzingViscoseFRnorm:1.70dtexx40mm. VerticalFlammabilityTestisthemainmethodused toevaluatethematerial'sburningbehaviors.suchas theburningextent(carbonizedareaanddamaged length),theafterflametime,theafterglowtime,andso on.Theprincipleofthismethodis:putthesample (whichhastherequiredsize)intoacombustionbox,and keepitburningfor12s;thenremovethefiresource, recordthesample'safterflametime.afterglowtime,and thedamagedlength.Thismethodisabasicwaytoreveal thematerial'sburningbehavior.Everycountryhasits relevantstandard.suchasAmericanStandardAATCC

3466,NFPAN0.7Oll966,GermanStandard

    DIN539O6,BritishStandardBS2963,andChinese StandardGB54551997,andsoon.

    Limitingoxygenindexexperiment:

    Instrument:burninginstrumentONl;

    Standard:GB54541997;

    Testmethod:testthepercentoftheoxygeninthe burninginstrumentwhenthesample'sdamagedlengthis 40mil1.

    Samplepreconditioning:placethesampleinan environmentallabwiththeconditionof(2O.5?O.5)?,

    andRHof(45?5)%for824h.

    Samplesize:150nlnl×65nlln.Sampleswerecutalong

    thewrapandtheweftdirections,respectively Portfire:butaneportfire.

    Note:TheexperimentsweredoneintheQualityTest CenterofSpecialProtectiveClothingoftheCPLA. 2ResultsandDiscussion

    2.1AppearanceoftheNomexfibers

    Imagesofthecross.sectionandlongitudinalviewof thefiber(SCCFig.1)weretakenbyusingtheelectronic microscope(modelTSM1).Onemayseethattheluster

    ofthetwofibersissimilartothatofthesilkandthereisno majordifferencebetweenthem.Theyaremostlyellipseor dumbbellincrosssections.

    Receiveddate:2008lO07

    *CorrespondenceshouldbeaddressedtoGENGWei.E-mail:gw6405@163.eom

    652JournalofDonghuaUniversity(Eng.Ed.)Vo1.26,No.6(2009) (a)Nome450(crosssection)(b)Nome462(crosssection)

    ?(c)Nome450(1ongitudina1)(d)Nome462(1ongitudina1) Fig.1SEMimagesofNomexfibers

    2.2Degreeofcrystallinityandorientation 2.2.1DEofcrystallinity

    ThecurveofXdiffraction(seeFig.2)isusedto analyzethedegreeofcrystallinityofNomex450and 462_z'.ItisshowninFig.2thattheareabelowthecurve ofT450(Nomex450)isgreaterthanthatofT462

    (Nomex462),sothedegreeofcrystallinityofNomex450 ishigherthanthatofNomex462.

    Fig.2'I1CUlVeofdiffraction

    2.2.2D,of啊捌btn

    XPrr6-polarizedlightmicroscopy(Nalightsource)is usedtotestthebirefrin~neeofNomex462andNomex 450.andtheirdoal:~refractiveindexeswerc0.096and 0.133,reslx~tivdy..icsthatthedegreeof

    orientationcfNo旺既450ishi-btkmthatofNomex

    462.Inotherwords,therel~larityofn~cromolecule arrangedr~ntintheaxialdirectionofNomex450fiberis higherthanthatofNomex462.

    2.3ed瞄玎量瞄lmp.ti

    Thete吐托telouptio~aproperty,and

    moistureregainofN0a450and462aresllowninTable

    1.111eresultswereconmmatwiththecrystallinityand orientationanalym.

    Table1Fiberphysicalproperties

    2.4Heatresbtlulce

    ThermalGravity(TG)testwascarriedoutforfibers ofNomex450,Nomex462,andLenzingVi~oseFR, andtheTGcurvesareshowninFig.3.TheTGcurves

    showedtherelationshipbetweentheresidualweightand thetemperatureL.Theheat-resistantstabilityofNomex 450and462isquitegood.Thelossoftheftweightwas lessthan1O%whenthetemperaturereached400?.

    andtheweightlosswasmainlyc^usodbytheevaporation ofwaterinthefiber.ThetwoNomexfiberslostweight rapidlywhenthetcmperaturereached43O?.the

    residualweightwas4O%atthismoment.Whenthe temperaturereached600?.theweightlosswasover

    8O%.Theresi~heofNomex450andNomex462were 3.35%and2.49%,respectively.

    ThehearesistanceabilityofLenzingViscoseFR waslowerthanthatofNomex.TheweightlOSSwas10% whenthetemperaturereached237?owingtothe

    highermoistureregainofthefiber.Theweightloss Nomex462

    Temperature/?

    Fig.3ThefiberTGcurve

    processoftheLenzingViscoseFRfiberwasdifferent fromthatofNomexfibers.Theprocessmaybedivided intotwosections:thefirstwasbetween220?and

    \lu??一:pl?0

    JournalofDonghuaUniversity(Eng.Ed.)Vo1.26,No.6(2009)653 276?.Inthissection.theweightlosswasquicker.In thesecondsection(from28O?to60O?),theweight

    lOSSwasslower.Whenthetemperaturereached600?,

    theresidualweightwasabout34%.Thefinalresidueof LenzingViscoseFR,mainlysomecarbide,wasremained about18.83%.

    2.5Preparationoftheblendedmaterialsandtheir

thermalproperties

    TherewasnomajordifferencebetweenNomex462 andNomex450asfarasthermalpropertieswere concerned.Nomex462andLenzingViscoseFRwere selectedforblendingtomaketheyarns.Nomex462was chosenowingtoitssmallermechanicalpropertydifference withLenzingViscoseFRcomparedwithNomex450(see Table1).

    Sevenvariousratiosoftheblendswereemployed,forthe sakeofsimplicity,theyweredesignatedAGrespectively.

    leratioarrangementispresentedin1'able2. Table2Theblendingratioofthetwoingredients SymbolRatioofNomex462/LenzingViscoseFR A

    B

    C

    D

    E

    F

    G

    0/100

    20/8O

    35/65

    50/50

    65/35

    80/20

    100/0

    Corresp0ndingyarns(finenessof28tex)were processedandfabrics(plainweave,warpdensityof250 setts/10cm,andweftdensityof250picks/10cm)wcre

wovenrespectivelybyusingrelatedyarns.

    2.5.1Analysisofburningbehaviors

    2.5.1.1Verticalburning

    TheresultofverticalburningtestisshowninTable3. Thelengthdamagedforallthespecimenswaslessthan Table3Thevertical-burningtestingresultsoftheblendingmaterial

    45mm,inmostofthecases.themoretheNomex462 content,thelessthedamagedlength.Itwasinterestingto findoutthattheminimumaldamagedlengthwasthe sampleFinsteadofG,andthelengthwasonly23mm. ThedamagedlengthsofsamplesCFwereallshorterthan

    thatofA.Thisindicatesthattheflameretardant performanceofCFisbetterthanAandG.Inother

    words,thedamagedlengthoftheblendingmaterialswas shorterthananyoftheirrespectivesinglecomponent materia1.Theexperimentaldataalsoindicatesthatthe FRperformanceofNomex462isbetterthanthatof LenzingViscoseFR.Intheprocessofburning,the specimenswerenotmelt,droplet,orsmoldering,and thedurativetimesofafterflamewereveryshort,andthe charredareasweresmal1.Itisfoundthatwiththe increasingcontentofLenzingViscoseFRfiber.the charredareaincreaseandthedurativetimeofafterflame becomelonger.

    2.5.1.2AnalysisoftheLimitingOxygenIndex(L0I) value

    TheLimitingOxygenIndex(LOI)valuesofeach blendingmaterialareshowninFig.4.Itshowsthatthe LoIvaluesofthespecimensareallover27%,indicating theirexcellentburningretardantproperties.Onemay

    anticipatethatnofurtherFRfinishingwouldbeneededforthe fabrics.TheFigurealsoshowsthattheLOIvaluewhenusing singlematerials(A,G)issmafler,allincreasedtrendis noticedwiththeincreaseofNomexcontentforthecasesofB. C,D,E,andF.TheLOIvaluesoftheblendingmaterial reached36.1%whentheblendingratioofNomex462and LenzingViscoseFRwas80/20.

    40

    30

    ,

    .

    ,

    2O

    10

    0

    ABCDFF(

    Designatedgroup

    Fig.4TheLOIvalueofeachblendingmaterial Thephenomenaabovecanbeexplainedasfollows: [===========

    1一一

    n=================]

    [==二二===二二=二二=

    .....,,..,...

    3EE盼一臻一

    m[=====

    网?

    [========

    654JournalofDonghuaUniversity(Eng.Ed.)Vo/.26,No.6(2009)

(1)Theflame-retardantpropertyoftheflame

    retardantfiberswasmainlyattributedtotheirstructural characteristics.Thepolymermolecularchainswere mainlycomposedofaromaticchainscontaining heterocyclicc.

    (2)TheflameretardantSandflamy5060wasaddedin thespinningsolutionofLenzingViscoseFR.Sandflamy 5060candecomposetogeneratedehydrateunderhigh temperature,whichwouldmakethefibersdehydratedand carbonized,andtheflammablegaswouldbereduced. (3)Thenonflammablegasandhigh-densitysteam werereleasedwhenthehybridmaterialswereburning.The formercandiluteoxygenandproduceflammablegasto reducethetemperatureincrease,thelattercancoverthe combustiblegasestomakethecombustiondistinguish. Theblendingmaterialsinvolvedinthisresearchhad goodflameretardantproperties,furtherfinishonthe blendedproductwasnotconsiderednecessary. 2.5.2ThermalGravity(T.G)analysis

    TGtestresultsofblendedmaterialsareshowninTable4. (1)Temperatureforweitlossof10%:theweit

    lossinthisstagewasmainlythewaterevaporationofthe materials.WiththeincreasingcontentofNomex462. temperaturesatweightloss10%raisedslightly.The temperatureforsampleGwhenweightlosewas10%was 412?.

    Table4TGtestingresultsoftheblendedmaterials (2)Thefastestrateofweightlossandtemperature.. ThefastestrateofweightlossbelongedtospecimenB. WiththeincreaseofNomex462contentintheblending

    materials,theweightlossratedecreased,butthe temperatureforthefastestweightlossrose.Itindicated thatthethermalstabilityoftheblendingmaterials improvedwhenthecontentofNomex462increased. (3)Temperatureofweightloss:specimenAFall

    hadtwostagesinweightlossprocess.Theweightlossin thefirstphasewasmainlythedecompositionofLenzing ViscoseFRfiberandthegasreleased.Inthisphase,with theincreasedNomex462content,thebeginningweight- losstemperatureraised,therangeoftemperaturebecame greater,buttherateofweightlossdecreased.The maximumalrateofweightlosswasthespecimenA,whose weightlossreached48.91%;theminimumalrateofweight losswasthespecimenF,anditsrateofweightlosswas only8.71%whenthetemperatureraisedfrom252?to

    365?.Itwasobviousthatthethermalstabilityhadbeen enhancedaftertheblendingofthetwomaterials. (4)ThesecondphaseofweightlOSS:theweightloss ofAwasnotsignificantowingtothecontinuous decompositionofLenzingViscoseFR.Thesecondphaseof weightlossofspecimensBFwasmainlythe

    decompositionoftheNomex462andtheLenzingViscose FR.aswellasthegasrelease.WiththeincreaseofNomex 462content,thebeginningweightlosstemperatureinthe

    secondphaseraised,thetemperaturerangeofweightloss becamegreater,andtherateofweightlossalsoincreased. AndthelargestrateofweightlosswasthespecimenF. (5)Theresidualweightat6oO?:whenthe

    temperaturereached600?.thedecompositionof

    specimenAhadbeenbasicallycompleted,sotheresidueof

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