无卤阻燃PP外文Word下载.docx

无卤阻燃PP外文Word下载.docx

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revised26August2003;

accepted5September2003.;

Availableonline24October2003.

Abstract

Flameretardantsforpolypropylene（PP）andtheirpotentialsuitabilityforuseinfibreapplicationsarereviewed.Fiveprincipaltypesofgenericflameretardantsystemsforinclusioninpolypropylenefibreshavebeenidentifiedasphosphorus-containing,halogen-containing,silicon-containing,metalhydrateandoxideandthemorerecentlydevelopednanocompositeflameretardantformulations.

Themosteffectivetodatecomprisehalogen–antimonyandphosphorus–brominecombinations,whichwhilehavinglimitedperformancealsoarefallingenvironmentalpressures.Alternativesarediscussedaswellasmeansofenhancingtheeffectivenessandhenceusefulnessofphosphorus–nitrogenformulationsnormallyusedatconcentrationstoohighforfibreinclusion.Ofspecialinterestisthepotentialforinclusionoffunctionalisednanoclaysandrecentobservationsthatcertainhinderedaminestabilisersareeffectiveatconcentrationsof1%orso.

AuthorKeywords:

Polypropylene;

Flameretardant;

Fibres;

Combustion;

Phosphorus;

Halogen;

Silicon;

Metalhydrate;

Nanoclay;

Nanocomposite

ArticleOutline

1.Introduction

1.1.Thedevelopmentofpolypropylenefires

1.2.Thepropertiesofpolypropylene

2.Thermalandcombustionbehaviour

3.Flameretardantsforpolypropyleneandpolypropylenefibres

3.1.Phosphorus-containingandintumescentflameretardants

3.1.1.Effectofheavymetalions

3.1.2.Effectofsilicon-containingspecies（seealsoSection3.3）

3.2.Halogen-containingflameretardants

3.3.Silicon-containingflameretardants

3.4.Metalhydroxidesandoxides（metalcompounds）

3.5.Nanocomposites

3.6.Othermethods

3.6.1.Graftingandcoating

3.6.2.Hinderedaminelightstabilisers

4.Conclusions

References

1.Introduction

Polypropylenewasthefirstsyntheticstereo-regularpolymertoachieveindustrialimportance[1]anditispresentlythefastestgrowingfibrefortechnicalend-useswherehightensilestrengthcoupledwithlow-costareessentialfeatures;

ithasshownconsistentgrowthofabout5%per 

annumforthelast10years[2].In1999,worldwideconsumptionofpolyolefinfibresexceeded5.5milliontonnesandtheyaccountedfor18%oftheworld'

ssyntheticfibreproduction[3].Polypropylenefibreshavebeenwidelyusedinapparel,upholstery,floorcoverings,hygienemedical,geotextiles,carindustry,automotivetextiles,varioushometextiles,wall-coveringsandsoon[4].

1.1.Thedevelopmentofpolypropylenefires

Thesynthesisofhighlycrystallineisotacticpolypropyleneusingstereospecificcatalystswaspatentedin1954byNatta[5].TheyusedheterogeneouscatalystsofthetypediscoveredbyZieglerforthelow-pressurepolymerizationofethylene 

toyieldlinearhigh-densitypolyethylene.CommercialpolypropyleneproductionwasinitiallyundertakenbyMontecatiniandsubsequentlyexpandedbyICIFibreswhointroducedtheir‘Ulstron’productinlate1950s[6].However,becauseofpatentrestrictionsassociatedwithfibreproduction,fibrouspolypropyleneoftenappearedinthemarketintheformoftapesandfilamentsratherthanfibres;

itwasnotuntiltheearly1960sthatstaplefibresstartedtobeseenonthemarket[7].Intheearly1970stheemergenceofextruded,orientatedfilmtechnologyledtoanexpansionofpolypropyleneend-uses,includingtapes/slit-filmandvariousfibrillatedandfibrousproducts[1].

Themonomerpropylene 

isahydrocarbongasmainlyproducedfrompetroleumrefining.Thepolypropylenechaincomprisesamonomerwithanasymmetriccarbon 

atomattheC2 

position,–CH2CH（CH3）–,andhencethepolymermayexistinthreetypes（isotactic,syndiotacticandatactic）ofmolecularconfigurationsdependingupontherelativeorientationsofthemethylsidegroups[7].Bothisotacticandsyndiotacticformshavemethylgroupssituatedregularlywithrespecttoadjacentgroupsalongthemolecularchainandhavefibre-formingcharacterduetotheirpotentialforcreatingorderinthepolymerstructure.Currently,isotacticpolypropyleneisthemaincommerciallyavailablestereoisomerforuseinorientedfibrefilmsandtapes.AveryrecentEUpatent,however,hasdescribedthepropertiesoffibreswhen0.5–50%byweightofsyndiotacticpolypropylenehavingamulti-modalmolecularweightdistributionisincludedwithatleast50%byweightofanisotacticpolypropylene[8].

Thereasonfortherapidexpansioninproductioncapacityforpolypropyleneisitsadvantageoverpolyethylene 

incostandproperties.Aneconomicedgeinrawmaterialcostandthehighefficiencycatalystshavemadepolypropyleneaverylow-costfibre-formingplasticmaterial.Anumberofpropertiesareresponsibleforthewidespreadusageofpolypropylene.ThegeneralpropertiesofisotacticpolypropyleneareshowninTable1 

[9].

Table1.Propertiesofisotacticpolypropylene

Fibre-formingatacticpolypropyleneispartiallycrystalline,i.e.itpossessesatwo-phasesystemcomprisingcrystallineandnon-crystallineregions.Themolecularchainsofcrystallineisotacticpolypropyleneexistinhelicalcoilshavingthreemonomerunitsper 

repeatinghelixwithalengthof0.65nmforeachrepeatunit.Themethylgroupsarearrangedsystematicallyaroundthehelixformingthreelateralrowsabout120°

apartandthusclosepackingispossible.

Thecrystallinemeltingpointofisotacticpolypropylenewithacrystallinityofaround45%andcontaining90–95%isotacticmaterialisquotedas165°

C[10].TheTg 

valueofisotacticpolypropylenerangesfrom?

6?

130to25°

Cdependingonmethodofmeasurementandheat-annealingtreatments[10].Atacticpolypropylenehasaglasstransitiontemperature（Tg）of?

112to?

115°

Candnodefinedmeltingpoint.Table2 

showsthethermodynamicalpropertiesofpolypropylene.

Table2.Thethermodynamicalpropertiesofpolypropyleneat230°

C

H,enthalpy;

S,entropy;

P=pressure.

Becauseofitswhollyaliphatichydrocarbonstructure,polypropylenebyitselfburnsveryrapidlywitharelativelysmoke-freeflameandwithoutleavingacharresidue.Ithasahighself-ignitiontemperature（570°

C）andarapiddecompositionratecomparedwithwoodandothercellulosicmaterialsandhencehasahighflammability.TheheatofcombustionforpolypropylenewasreportedbyEinseleetal.[11]tobe40kJ/gandthisishigherthanmanyotherfibre-formingpolymers.GurniakandKohlhaas[12]investigatedthecombustibilitytestscarriedoutonfourdifferentbackingfabrics:

spunbondedpolypropylene,wovenpolypropylenetapewithnylon/polypropylenebondedstaplefibrefabrics,spunbondedBikofilament（polyestercore,nylonsheath）,andFreudenberg'

sLutradurT5012spunbondedpolyester.Theyfoundthatthelowestflammabilitywasachievedbythespunbondedpolyesterproduct.Thisisasignificantobservationinthatpolypropylenecompeteswithpolyesterintermsoftensilepropertiesandprice,butitdoeshaveinferiorfireperformance.

Polypropylenepyrolysisisdominatedbyinitialchainscissions;

consequentlyconsiderableresearchhasbeenundertakenintheconversionofwastepolypropyleneintocleanhydrocarbonfuels[13 

and14]orothervaluableproductssuchaslubricants[15 

and16].ThethermaldegradationofbothisotacticPPandatacticPPhasbeeninvestigatedundernon-isothermalconditions.Themaximumvolatileproductevolutiontemperaturewas420°

CforatacticPPand425°

CfortheisotacticPP.Therecoveryofcarbon 

asorganicvolatileproductscompriseddienes,alkanes,andalkenes.MajorcompoundsareforinstanceC9compounds,like2-methyl-4-octene,2-methyl-2-octene,2,6-dimethyl-2,4-heptadiene,2,4-dimethyl-1-heptene,2-methyl-1-octene.Thehydrogencontentofpyrolysisproductsobtainedbyflashpyrolysisat520°

C,indicatesthemagnitudeoftheflammabilityproblemintermofitsfuel-formingpotential[17].Anabundanceofunsaturatedvolatilefuelfragmentsrenderstheflameretardationproblemevenmoresevereasthelonger,less-volatilemoleculesbehaveassecondaryfuelsources,whichdecomposefurther[18 

and19].

Coolflamecombustionofpolypropyleneat350°

Cleadstotheformationoftoxiccompoundswhichcancausedeathinmice,probablybecauseofincompletecombustionandCOformation[20].WhilethefirehazardcausedbytextilesingeneralhasbeenreviewedbyHorrocks[21]andChristian[22],theparticularhazardofpolypropylenewasnotedintheManchesterWoolworthFireof1979wherepolypropyleneupholsterycoversoverpolyurethane 

foamfillinginastackedfurniturepile 

wereidentifiedasthefirstmaterialignitedandwereresponsiblefortherapidgrowthofthatfire.The12deathsassociatedwiththisfiregaverisetotheneedtouseflameretardanttextilesinUKdomesticfurnishingsforthefirsttimein1980[23].

Hirschler[24]studiedthefirehazardandtoxicpotencyofthesmokefromburningpolypropylenein1987.Grand[25]investigatedtheeffectofexperimentalconditionsontheevolutionofcombustionproductsofpolypropylenebyusingamodifiedtoxicitytestapparatus.In2000,ShemwellandLevendis[26]studiedtheparticulate（soot）emissionsfromburningpolypropyleneandfourotherplastics.Resultsshowedthatboththeyieldsandthesizedistributionsoftheemittedsootwereremarkablydifferentforthefiveplasticsburned.Sootyieldsincreasedwithanincreaseofthenominalbulk（global）equivalenceratio（φ）.Combustionofpolystyreneyieldedthehighestamountsofsoot