Preparation of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation

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Preparation of aqueous dispersion of thermoplastic

sizing agent for carbon fiber by emulsion/solvent

evaporation

Isabelle Giraud, Sophie Franceschi-Messant, Emile Perez, Colette Lacabanne,

Eric Dantras

To cite this version:

Isabelle Giraud, Sophie Franceschi-Messant, Emile Perez, Colette Lacabanne, Eric Dantras.

Prepara-tion of aqueous dispersion of thermoplastic sizing agent for carbon fiber by emulsion/solvent

evapo-ration. Applied Surface Science, Elsevier, 2013, vol. 266, pp. 94-99. �10.1016/j.apsusc.2012.11.098�.

�hal-00835632�

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DOI:10.1016/j.apsusc.2012.11.098

Official URL:

http://dx.doi.org/10.1016/j.apsusc.2012.11.098

This is an author-deposited version published in:

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Eprints ID: 8782

To cite this version:

Giraud, Isabelle and Franceschi-Messant, Sophie and Perez, Emile and

Lacabanne, Colette and Dantras, Eric Preparation of aqueous dispersion of

thermoplastic sizing agent for carbon fiber by emulsion/solvent evaporation.

(2013) Applied Surface Science, vol. 266 . pp. 94-99. ISSN 0169-4332

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Preparation

of

aqueous

dispersion

of

thermoplastic

sizing

agent

for

carbon

ﬁber

by

emulsion/solvent

evaporation

Isabelle

Giraud

a

_,

_Sophie

_{Franceschi-Messant}

a

_,

_Emile

_Perez

a,∗

,

Colette

Lacabanne

b

,

Eric

Dantras

b a_Laboratoire_des_I.M.R.C.P.,_UMR₅₆₂₃_CNRS,_Université_Paul_Sabatier,₃₁₀₆₂_Toulouse_Cedex_09,_France

b_Laboratoire_de_Physique_des_Polymères,_CIRIMAT,_Institut_CARNOT,_Université_Paul_Sabatier,₃₁₀₆₂_Toulouse_Cedex_09,_France

Keywords: Sizing Carbonﬁbers Composites Thermoplasticpolymer Aqueousdispersion Emulsion/solventevaporation

a

b

s

t

r

a

c

t

Inthiswork,differentsizingagentaqueousdispersionsbasedonpolyetherimide(PEI)wereelaboratedin ordertoimprovetheinterfacebetweencarbonfibersandathermoplasticmatrix(PEEK).Thedispersions wereobtainedbytheemulsion/solventevaporationtechnique.Tooptimizethestabilityandthefilm formationonthefibers,twosurfactantsweretestedatdifferentconcentrations,withdifferent concen-trationsofPEI.Thedispersionsobtainedwerecharacterizedbydynamiclightscattering(DLS)andthe stabilityevaluatedbyanalyticalcentrifugation(LUMiFuge).Theselecteddispersionsweretestedforfilm formationabilitybyscanningelectronmicroscopy(SEM),andthesizingperformancewasassessedby observationofthefiber/matrixinterfacebySEM.TheresultsrevealedthatanaqueousdispersionofPEI, stabilizedbysodiumdodecylsulfateasthesurfactant,ledtoverystablesizingagentaqueousdispersion withidealfilmformationandbetterinterfaceadhesion.

1. Introduction

Carbonfiberiswidelyusedasareinforcingmaterialin com-posites,especiallyinadvancedcomposites[1,2].Ascarbonfibers arebrittle,manyproblems,suchasfilamentbreakageandfluffing, ariseduetomechanicalfrictionduringthemanufacturingprocess

[3–5].Therefore,carbonfibersaregenerallysizedorcoatedbya sizinglayeronthesurface,whichisusuallyobtainedfroma solu-tionoremulsionconsistingofpolymericcomponents[6,7].Sizing easesfiberhandlingandcanalsoprovideacouplingagentforthe fiber/matrixbond [8–11]. Thenatureof thesizingis oftenkept secretbymanufacturersofcarbonfibers.However,sizingischosen accordingtothenatureofthematrixandisgenerallyapre-polymer orpolymer.Mostofthecompositesaremadefromepoxyresin,and sizingagentsareoftenofthesamenature[5,12–14].Thisisa prob-lemwhenthematrixisahigh-temperaturethermoplasticpolymer sincethedegradationtemperatureofthistypeofsizingisaround 250◦_C _[15]_. _For _polyimides, _PEEK _and _other _{high-temperature}

thermoplastic polymers,thefunctional groups provided bythe traditionalepoxy-compatiblesizingdonotreactchemicallywith thesepolymersandweakinterfacialshearstrengthsresult[16]. Moreover,forcompositesmoldedwithpolyimidesorPEEK,high processingtemperaturesduringmanufactureandcontinuoususe

∗ Correspondingauthor.

E-mailaddress:perez@chimie.ups-tlse.fr(E.Perez).

inhigh-temperatureenvironmentsdegradetheepoxysizingand, consequently,weakenthefiber/matrixinterface,producingvoids anddelaminations[17–19].Alloftheseobservationsunderlinethe importanceofhavingsizingthatissuitableforhigh-temperature thermoplasticmatrices.Fromapracticalpointofview,thesizing formulationshouldbeeasytouse,non-toxicandenvironmentally friendly.Inthispaper,wereportthefirstexampleofpreparation anaqueousdispersionofathermoplasticsizingagentforcarbon fiberbyemulsion/solventevaporation.

2. Experimental 2.1. Materials

ThepolyetherimidePEI(Ultem1000)wasobtainedfromSabic®_.

Thesodiumdodecylsulfate(SDS)andthechloroformwere pro-videdbySigma–Aldrich,thebenzalkoniumchloride(BC)wasfrom Fluka (C12 60%, C14 40%). The AS4 carbon ﬁber tow, provided

byHexcel,wastreatedunsizedandcontained12,000ﬁbers.The polyetheretherketone(PEEK)providedbyVictrexwasa 100mm thickﬁlm.TheremoldingagentwasCIREX041WBfromSICOMIN. 2.2. PreparationofPEIdispersionsbyemulsion/evaporation

In order to reduce thetoxicity and to respect the environ-ment,organicsolventsmustbeavoidedintheﬁnalsizingagent formulation.Forthesereasons,wedecidedtoelaborateaqueous

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Fig.1.Schematicrepresentationofthepharmaceuticalemulsiﬁcation/evaporationprocess.

dispersions.Thesecanbemadebyavarietyofmethods[20–23]

leading,attheend,tostablehydrophobicparticlesinwater.The preparationprocessdescribedherewaslargelyinspiredby emul-sion/solventevaporation,anencapsulationtechniqueusedinthe pharmaceuticalindustrytoprepareaqueousdispersionsof poly-mernanoparticlesormicrospheres.

Emulsion/solvent evaporation involves a two-step process (Fig.1):theemulsiﬁcationofa polymersolutioncontainingthe encapsulatedsubstance,followedbyparticlehardeningthrough solventevaporationandpolymerprecipitation.Duringthewater emulsiﬁcation, the polymer in solution in the volatile, water-immisciblesolventisbrokenintomicrodropletsbytheshearstress producedbyeitherahomogenizerorasonicatorinthepresenceof asurface-activeagentuntilthepolymerprecipitates[24–27].

Thismethodwasusedtoprepareastableaqueousdispersionof PEIasthesizingagent.Weusedtwodifferentsurfactants,sodium dodecylsulfate(SDS)andbenzalkoniumchloride(BC)atdifferent concentrations(0.3%,0.5%and1wt%).Thefinalconcentrationsof PEIwere0.1%,0.3%,0.5%and1wt%.ThePEIdispersionat0.5wt%ina 0.5wt%surfactantsolutionwaspreparedasfollows.Ina5-mLflask, 0.1005gofPEIwasdissolvedin2mLofchloroform.Thissolution waspouredintoanotherflaskcontaining20mLofthesurfactant solution.Themixturewasemulsifiedbyultrasoundshearing(Vibra Cell,BioblockScientific600W,20Hz).Theshearinglasted5minat power4.Awaterbathwasusedtomaintainthesolutionatroom temperature.Then,magneticstirringoftheemulsionat1200rpm for12hallowedtotalevaporationofthechloroform.

2.3. CharacterizationofPEIdispersions 2.3.1. Particlesizeanalysis

Dynamiclightscattering(DLS)wasperformedusingaMalvern InstrumentsNanoZSwithaHe–Nelaser(633nm)atascattering angleof173◦_and_at₂₅_±₁◦_C._The_hydrodynamic_mean_diameter_of

thenanoparticleswasdeterminedusingthesoftwareprovidedby MalvernInstruments.TheContinmodelwasappliedtoobtainsize data.Alltheauto-correlationfunctionﬁtswerecheckedandfound tobeinaccordancewiththeexperimentaldata.Fivemeasurements weremadeoneachsamplewithanaccuracyofabout2nm. 2.3.2. Evaluationofstabilityusinganalyticalcentrifugation

Aseparationanalyzer(LUMiFuge,L.U.M.Berlin,Germany)was usedtodeterminetheseparationbehaviorofdispersionsunderthe inﬂuenceofvariouscentrifugalforces(5–1000×g).Thisapparatus isbasedona low-speedcentrifugecombinedwithan optoelec-tronicmeasuringsystemthatrecordsthelighttransmissionover theentire sample cuvette (Fig. 2). The cuvettes containingthe

suspensionare positioned in thehorizontal planeon therotor ofthecentrifuge.Duringcentrifugationalightsourcepositioned abovetherotoremitsradiation(near-infrared)ontothesample. TransmittedlightisdetectedbyaCCDlinesensorbelowtherotor planeandisanalyzedbyamicrocontroller,whichgeneratesa light-transmissionproﬁleof thesampleareafor everymeasurement step.

This technique is very appropriate for the study and opti-mizationofverystableaqueousdispersions.Thecentrifugalforce acceleratesthedestabilizationofthedispersionandrapidly deter-minestheshelflifeofthedispersion[28].Moreover,thepossibility ofstudying8samplesatthesametimeenablesdifferent formu-lationstobecomparedimmediately[29,30].Thedispersionsare naturallystableover6monthssowechosetosimulate3yearsof aging.Thedataacquisitioncorrespondedto255proﬁlesrecorded everyeverysecondsat4000rpm.Thetemperaturewas20◦_C.

2.4. Sizingtreatmentofcarbonﬁberandcompositepreparation 2.4.1. Sizingofcarbonﬁber

Differentmethodscanbeusedtosizecarbonfibers,such as electrodeposition[31,32]orelectropolymerization[33,34],butthe mostcommonisbathcoating.Wetestedthesizingatlaboratory scaleso,inthiscase,themostsuitabletechniquewastospraythe dispersiondirectlyontothefibersurface.Anunsizedfibertowwas strainedbyaweighttokeepitvertical,allowinguniformspraying ofthesizingatthefibersurface(Fig.3).Aftersizing,thefiberswere driedatroomtemperature.

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Fig.3. Schematicrepresentationofthesizingprocess.

2.4.2. Compositepreparation

WealsopreparedPEEK/unidirectionalcarbonfibersamplesat laboratoryscale.Thesampleswerepreparedbyhotpress mold-ing.ThepressusedwasaCarver4128CEequippedwithheating plates.Theprocessingtookplaceinseveralsteps.Thesamplewas firstprepared,thenmoldedinthehotpressandfinallycooledand remolded.Inordertokeepallthecarbonfibersinthesame direc-tionduringthedifferentsteps,thestrandsofcarbonfiberwere insertedinafoldedPEEKfilm(Fig.4).

The sample was then placed in an aluminum mold previ-ouslycoatedwiththeremoldingagent.Thenthemoldwasplaced betweenthetwoplates,previouslyheatedto400◦_C,_and_kept_in

contactfor15mintoallowthePEEKtomeltuniformly.6MPaof pressurewasthenappliedfor30stoletthePEEKimpregnatethe fibers.Finally,thesamplewasaircooledandremoldedatroom temperature.Thefinalsamplecontained30wt%ofcarbonfibers. 2.5. CharacterizationofPEIfilmsandcomposite

2.5.1. Scanningelectronmicroscopy(SEM)analysis

Thedifferentsampleswereexaminedusingascanningelectron microscope(JEOLJSM6700F)withanacceleratingvoltageof5kV. Theﬁlmsobtainedafternaturaldryingatroomtemperaturewere mountedonaluminumstubsand sputtercoatedwithgold.The compositeswerefreezefracturedinordertoobservetherupture faces.

3. Resultsanddiscussion 3.1. Sizingagentformulation 3.1.1. Stabilitystudy

We selected PEIas thesizing agent becauseit is a thermo-plastic polymer with high heat resistance [35], miscible with polyetheretherketone(PEEK)[36],andsolubleinchlorinated sol-ventslikechloroform.Severalfactorsinﬂuencethestabilityofthe dispersion,suchasthenatureandtheamountofsurfactant. Usu-ally,thechoiceofsurfactantdependsonthenatureoftheparticles and,in particular,theirsurface charge.SincePEIhasnospecial charge,thesurfactantcanbeanionicorcationic.Itisalsoimportant

Fig.4. Schemeofthesamplepreparation.

Fig.5.Inﬂuenceofthenatureandconcentrationofthesurfactantonthemean particlediameter([PEI]=0.5wt%).

todeterminetherightquantityofsurfactanttomaintainastable dispersion.PEIconcentrationisalsoanimportantparameter.The emulsion/evaporationmethodisnotsuitableforthepreparation ofconcentrateddispersionsbut,inthecaseofsizing,thisisnota limitationbecausetheconcentrationofpolymerdoesnotexceed 1wt%[37,38].

First,westudiedtheinﬂuenceofthenatureandthe concentra-tionofthesurfactant,andalsotheinﬂuenceofthePEIconcentration onthecharacteristicsofthesizingdispersions.

Theﬁrstparametertobeconsideredwastheparticlesizeas itiswellknownthatthesmallertheparticlesare,themore sta-blethedispersionwillbe.Dynamiclightscatteringmeasurements (DLS)wereperformedonallthedispersions.Theinﬂuenceofthe surfactantonthemeandiameterofparticlescanbeseeninFig.5.

Themeandiametersoftheparticleswerelessthan100nmand favored stabledispersions.The natureofthesurfactantdidnot haveasignificanteffectontheparticlesizeeventhoughthe par-ticlesseemedsmallerwiththeBCsurfactant.Ontheotherhand, thediametersvariednoticeablywiththesurfactantconcentration. Thehighertheconcentrationwas,thesmallerweretheparticles. Atlowconcentration,therewasnotenoughsurfactantto main-tainsmalldropletsofchloroformandthisdeterminedthefinalsize oftheparticles.Althoughthesmallestparticleswereobtainedfor 1wt%,theconcentrationof0.5%waspreferredinordertominimize theamountofsurfactantinthefinalformulation.

Thesamestudywasperformedtoobservetheinﬂuenceofthe PEIconcentration(Fig.6).Theparticlesizeincreasedquitelinearly withtheconcentrationforbothsurfactantsbutthemean diam-eterremainedunder 100nm.This resultwasrelated toseveral factors.Theﬁrstwastheratiobetweentheconcentrationof surfac-tantandtheamountofchloroformphasecontainingthedissolved PEI[23].Thesecondwastheviscosityoftheorganicphase[23].

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Fig.7.EffectofthePEIconcentrationontheclariﬁcationkineticsfordispersionsat0.3%BC.

IncreasingthePEIconcentrationinchloroformincreasedthe vis-cosityofthesolution.Giventhattheshearforceswerealwaysthe same,whentheconcentrationofPEIwastoohigh,therewasnot sufﬁcientenoughavailabletocreatesmalldropletsofchloroform. Theparticlesizeforthelowestconcentrationswasverysmall, lead-ing,inprinciple, tothemoststable dispersions.However,for a sizingformulation,thedispersionsmusthaveaminimumof0.5% or1wt%ofPEI.

An interesting stability analysis consisted in determining a destabilization velocity by accelerating the gravitation by cen-trifugation. This kind of analysis could be performed withthe “LUMiFuge”apparatus.Thistechniqueissuitabletooptimizevery stabledispersions(stableformorethan6months).

Fromtheproﬁles,anintegraltransmissionwascalculatedasa functionoftime.Forinstance,theinﬂuenceofthePEIconcentration onthestabilitycanbehighlightedimmediately(Fig.7).

Fromthisgraph,aclarificationvelocity,correspondingtothe slopeofthefirstlinearpartofthecurves,wascalculatedbythe “SEPView”software.Thesteepertheslope,themoreunstablethe dispersion.Theclarificationvelocitywascalculatedforthedifferent dispersionsandcomparedsoastohighlighttheeffectofdifferent parameters.

AsshowninFig.8,thenatureofthesurfactantdidnothavea significantinfluenceonthevelocity,exceptfor0.1wt%PEIsolution, whereBCwaslessefficient.Consideringthesurfactant concentra-tion,itseemsthat,from0.5wt%,thestabilityreachesaplateau.This resultindicatesthatitisnotnecessarytousemorethan0.5wt% surfactantsolutionstoincreasethestability.

As expected, the PEI concentration had a major impact on thedispersionstability (Fig.9).Theclariﬁcationvelocitytripled between0.5%and1wt%.Althoughtheshelflifecannotbe deter-mineddirectly from theclariﬁcation velocity, the real stability

Fig.8. Inﬂuenceofthenatureandconcentrationofthesurfactantontheclariﬁcation velocity([PEI]=0.5wt%).

periodextrapolatedfromthedatawasestimatedtobearound6 monthsforthe1%PEIdispersion.

Consideringtheaboveresults,boththetestedsurfactantswere usable.However,benzalkoniumchloridemightbemoreinteresting becauseofitsantimicrobialandlowfoamingproperties. Concern-ingthedifferentconcentrations,agoodcompromiseseemstobe 0.5wt%ofsurfactantand0.5wt%ofPEI.

3.1.2. Filmformation

Forsizing,thecoating,andconsequentlytheformationofafilm, isaveryimportantproperty.Alltheaqueousdispersionsprepared wereabletoformfilmsafterwaterevaporation.Toensurethe qual-ityofthefilm,twochosendispersionswereobservedbySEM.One wasmadewithSDSandtheotherwithBC,andbothcontained 0.5wt%ofsurfactantand0.5wt%ofPEI.

ThesurfaceaspectofthePEIfilmobtainedwithSDSwasvery homogeneous(Fig.10).Thecrackswereduetouncontrolled evapo-ration.Thisparameterwillneedtobetakenintoaccountforfurther applications.Themagnificationofthisfilmshowspartiallyfused PEIparticles(Fig.11).Thisobservationistypicaloflatexfilm for-mation,andisidealforahomogeneouscoating.

ThePEIﬁlmformedbytheBCdispersionwasverydifferent.

Fig.12isanSEMobservationofthisfilmshowingaheterogeneous surface.Themagnificationshowsthat,infact,theparticlesformed agglomeratesbutdidnotfuse(Fig.13).Thedifferenceinfilm forma-tioncouldbeexplainedbytheabilityofthesurfactanttobedrained outoftheevaporatingfilm[39–41].Wehavetoconsiderthe affin-ityofthesurfactantwiththesurfaceofthePEIparticlestoexplain thisbehavior.Itseemsthat,comparedtoBC,SDShasalower affin-itywiththesurfaceoftheparticlesandismainlydrainedoutofthe film,leadingtothefusionoftheunprotectedparticlesandfinally toahomogeneousfilm.

Fig.9. InﬂuenceofthePEIconcentrationontheclariﬁcationvelocity ([surfac-tant]=0.5wt%).

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Fig.10.SEMobservationoftheﬁlmfromtheSDSdispersion.

Fig.11.MagniﬁcationofFig.10.

Fig.12.SEMobservationoftheﬁlmfromtheBCdispersion.

Fig.13.MagniﬁcationofFig.12.

Consideringtheseﬁlmformationresults,thebestdispersions forasizingapplicationseemtobethoseobtainedwithSDSasthe surfactant.Itisveryimportanttoobtainahomogeneouscoatingon thecarbonﬁbers.

3.2. Sizingevaluation

Theaimofthisstudywastoelaborateastableaqueous disper-sionusableasathermoplasticsizingformulationforcarbonfibers. Thesizing hasvariousroles,suchasfacilitating thehandlingof fibersandimprovingtheinteractionsbetweenthematrixandthe fibers.

Toevaluatetheeffectofthisnewsizing,PEEK/carbonfiber com-positesweremade;onewithunsizedcarbonfibersandanother withPEIsizedcarbonfibers.Thechosensizingwastheaqueous dispersionwith0.5wt%ofPEIand0.5wt%ofSDS.Thebestwayto highlighttheinfluenceofthesizingwastoobservethefiber/matrix interface.Forthatpurpose,thecompositeswerefreezefractured transversallyandobservedbyscanningelectronmicroscopy.

Fig.14correspondstoanunsizedcarbonﬁbercompositeand,as wecansee,therearevoidsandnointeractionsbetweenthePEEK matrixandthecarbonﬁbers.Incontrast,theinterfacebetweenthe

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Fig.15. PEIsizedcarbonﬁbercomposite.

compositeandthePEIsizedcarbonfibersiscontinuous(Fig.15). Inthiscase,thereisarealbondbetweenthePEEKandthecarbon fibers.Theseobservationsconfirmnotonlythatthesizingremains duringthecompositeprocessingbutalsothatthematrixandthe carbonfibersareconnectedbythesizingagent.

4. Conclusions

Theanalysesperformedonthedifferentaqueousdispersions revealedthatthequantityofparticleswasasignificantfactorfor stability.TheparticlesizeincreasedgreatlywiththePEI concentra-tion,whichtendedtodecreasethestabilityofthedispersion.The LUMiFugestudyconfirmedthisresult.ThebestPEIconcentration obtainable bytheemulsion/evaporation technique was0.5wt%. Thedispersions werestable1 yearat 0.5wt%,nevertheless the dispersionat1wt%remainedstablefor3months.Concerningthe natureofthesurfactant,benzalkoniumandSDSallowedstable dis-persionstobeobtained.Nevertheless,thebenzalkoniumdispersion didnotformahomogeneousfilmandsowasnotsuitablefor a sizingapplication.Incontrast,withSDSdispersion,thefilmwas reallyuniformandweobservedacoalescencephenomenon typi-caloflatexfilmformation.Theconcentrationofthesurfactantalso hadaninfluenceontheparticlesizeandstability,and0.3%wasnot enoughtoobtainagooddispersion.Thegaininstabilityobtained at1%didnotjustifytheuseofsuchaconcentrationconsidering thattherewasonly0.5wt%ofPEI.Sothebestconcentrationof surfactantwas0.5wt%.

Consideringalltheresults,thechosendispersionforsizingwas 0.5%PEIand0.5%SDS.Theefﬁciencyofthisnewsizingagent aque-ousdispersionwasappreciatedthroughSEMobservations,which showedacontinuousinterfacebetweenthecarbonﬁbersandthe PEEKmatrix.

Acknowledgements

WethankMrJ.M.Bergerat,AIRBUSIndustry,ToulouseFrance, for useful discussions and advice. The ﬁnancial support of FUI INMAT2andAIRBUSisgratefullyacknowledged.WealsothankMr D.KemmishandMrA.WoodfromVictrexInc.,fortheirinsightful commentsandfruitfuldiscussions.

References

[1] P.Morgan,CarbonFibersandTheirComposites,CRCPressTaylor&Francis Group,NewYork,2005.

[2] D.D.L.Chung,CarbonFiberComposites,Butterworth-Heinemann,Newton, 1994.

[3] B.Fernandez,A.Arbelaiz,A.Valea,F.Mujika,I.Mondragon,PolymerComposites 25(2004)319–330.

[4]W.Chen,Y.Yu,P.Li,C.Wang,T.Zhou,X.Yang,CompositesScienceand Tech-nology67(2007)2261–2270.

[5] A.Paipetis,C.Galiotis,CompositesPartA:AppliedScienceandManufacturing 27(1996)755–767.

[6] N.Dilsiz,J.P.Wightman,Carbon37(1999)1105–1114. [7] R.B.Guan,Y.G.Yang,J.T.Zheng,Fibercomposites1(2002)23. [8] T.Q.Li,M.Q.Zhang,H.M.Zeng,Polymer40(1999)4307–4313.

[9] S.-L.Gao,J.-K.Kim,CompositesPartA:AppliedScienceandManufacturing32 (2001)775–785.

[10]L.T.Drzal,M.J.Rich,M.F.Koenig,P.F.Lloyd,TheJournalofAdhesion16(1983) 133–152.

[11]Z.Dai,F.Shi,B.Zhang,M.Li,Z.Zhang,AppliedSurfaceScience257(2011) 6980–6985.

[12] Z.Dai,B.Zhang,F.Shi,M.Li,Z.Zhang,Y.GU,AppliedSurfaceScience257(2011) 8457–8461.

[13]P.Ren,G.Liang,Z.Zhang,PolymerComposites27(2006)591–598.

[14]V.S.Mironov,M.Park,J.Kim,S.H.Lim,C.R.Choe,JournalofMaterialsScience Letters20(2001),1211–1211.

[15]A.Bledzki,E.Fabrycy,A.Kwasek,JournalofThermalAnalysisandCalorimetry 29(1984)989–994.

[16]D.M.Blackketter,D.Upadhyaya,T.R.King,J.A.King,PolymerComposites14 (1993)430–436.

[17]T.K. O’Brien, Journal of Reinforced Plastics and Composites 7 (1988) 341–359.

[18]P.Davies,W.J.Cantwell,H.H.Kausch,JournalofMaterialsScienceLetters9 (1990)1349–1350.

[19]A.Todoroki,H.Kobayashi,CompositesScience andTechnology52(1994) 551–559.

[20]S.Freitas,H.P.Merkle,B.Gander,JournalofControlledRelease102(2005) 313–332.

[21]C.Zhang,G.Zhang,V.Ji,H.Liao,S.Costil,C.Coddet,ProgressinOrganicCoatings 66(2009)248–253.

[22]P.R.Nepal,M.-K.Chun,H.-K.Choi,InternationalJournalofPharmaceutics341 (2007)85–90.

[23] M.Li,O.Rouaud,D.Poncelet,InternationalJournalofPharmaceutics363(2008) 26–39.

[24]T.R.Tice,R.M.Gilley,JournalofControlledRelease2(1985)343–352. [25] K.S.Soppimath,T.M.Aminabhavi,A.R.Kulkarni,W.E.Rudzinski,Journalof

Con-trolledRelease70(2001)1–20.

[26]S. Freiberg, X.X. Zhu,International Journal of Pharmaceutics 282 (2004) 1–18.

[27] Z.ElBahri,J.-L.Taverdet,JournalofAppliedPolymerScience103 (2007) 2742–2751.

[28]M.Kuentz,D.Röthlisberger,EuropeanJournalofPharmaceuticsand Biophar-maceutics56(2003)355–361.

[29] T.Sobische,H.Heb,H.Niebelschütz,U.Schmidt,ColloidsandSurfacesA: PhysicochemicalandEngineeringAspects162(2000)1–14.

[30]T.Sobische,D.Lerche,ColloidsandSurfacesA:Physicochemicaland Engineer-ingAspects331(2008).

[31]A.Bismarck,A.F.Lee,A.S.Sarac,E.Schulz,K.Wilson,CompositesScienceand Technology65(2005)1564–1573.

[32]A.S.Sarac,E.A.Parlak,E.Sernath,T.Cakir,JournalofAppliedPolymerScience 104(2007)238–246.

[33] B.Lin,R.Sureshkumar,J.L.Kardos,ChemicalEngineeringScience56(2001) 6563–6575.

[34]C.Dalmolin,S.C.Canobre,S.R.Biaggio,R.C.Rocha-Filho,N.Bocchi,Journalof ElectroanalyticalChemistry578(2005)9–15.

[35]R.Torrecillas,A.Baudry,J.Dufray,B.Mortaigne,PolymerDegradationand Sta-bility54(1996)267–274.

[36]G.Crevecoeur,G.Groeninckx,Macromolecules24(1991)1190–1195. [37]R.L.Zhang,Y.D.Huang,L.Liu,Y.R.Tang,D.Su,L.W.Xu,AppliedSurfaceScience

257(2011)3519–3523.

[38]D.D.L. Chung,CarbonFiberComposites,Butterworth-Heinemann,Newton, 1994,pp.91–93.

[39]E.Kientz,Y.Holl,ColloidsandSurfacesA:PhysicochemicalandEngineering Aspects78(1993)255–270.

[40] J.Mallégol,J.-P.Gorce,O.Dupont,C.Jeynes,P.J.McDonald,J.L.Keddie,Langmuir 18(2002)4478–4487.

[41]A.Tzitzinou,P.M.Jenneson,A.S.Clough,J.L.Keddie,J.R.Lu,P.Zhdan,K.E. Treacher,R.Satguru,ProgressinOrganicCoatings35(1999)89–99.