具有正温度系数特性的导电低密度聚乙烯基复合材料的摩擦磨损性能

具有正温度系数特性的导电低密度聚乙烯基复合材料的摩擦磨损性能Abstract:

Inthispaper,conductivelow-densitypolyethylene-basedcompositematerialswithpositivetemperaturecoefficient(PTC)characteristicswerefabricatedandtheirfrictionandwearpropertieswereinvestigated.TheresultsshowedthatthePTCmaterialsexhibitedexcellentfrictionstabilityandwearresistance,whichcanbeattributedtotheincreasedcontactareaandenhancedshearstrengthbetweenthePTCparticlesandthepolymermatrixduringthePTCeffect.Theoptimizedcompositionofthecompositematerialwasfoundtobe15wt%PTCparticleswithameandiameterof20μm,resultinginahighPTCeffectandstablefrictionandwearproperties.

Introduction:

ConductivepolymericmaterialswithPTCcharacteristicshaveattractedextensiveattentionduetotheirpotentialapplicationsinelectronicdevices,sensors,andself-regulatedheaters.ThePTCeffectreferstothephenomenonthattheelectricalconductivityofamaterialincreasesdramaticallywiththeincreaseoftemperatureaboveacertainthreshold.Suchacharacteristicallowsthematerialtoself-regulateitstemperatureandcurrent,protectingthedevicefromoverloadinganddamage.

However,thePTCeffectmayalsoaffectthefrictionandwearpropertiesofthematerials,whichhavebeenrarelystudiedintheliterature.ItisessentialtoinvestigatethefrictionandwearbehaviorsofPTCmaterialstodeterminetheirfeasibilityforpracticalapplications.Inthiswork,conductivelow-densitypolyethylene-basedcompositematerialswithPTCcharacteristicswerefabricated,andtheirfrictionandwearpropertieswereevaluatedbyusingapin-on-disktribometer.

MaterialsandMethods:

Thelow-densitypolyethylene(LDPE)usedinthisstudywaspurchasedfromChinaPetroleum&ChemicalCorporation,withameltflowindexof12g/10minat190℃andadensityof0.915g/cm3.ThePTCparticlesweresynthesizedbyusingBaTiO3particlesasthesubstrateandcoatingthemwithcarbonblackbyaprecipitationreaction.ThePTCparticleshadameandiameterof20μmandacarbonblackcontentof10wt%.Thecompositematerialswerepreparedbyameltblendingmethodusingatwin-screwextruderatatemperatureof190℃andascrewspeedof30rpm.ThePTCparticleswereaddedtotheLDPEmatrixatvariousweightratiosof0,5,10,15,and20wt%.

Thefrictionandweartestswerecarriedoutusingapin-on-disktribometerwithasteelball(6mmindiameter)asthefrictioncounterpart.Theloadappliedtothesamplewas1N,andtheslidingspeedwas0.1m/s.Thedurationofeachtestwas30minuteswithaslidingdistanceof500m.Thefrictioncoefficientandwearratewererecordedduringthetest.

ResultsandDiscussion:

ThePTCparticlesweredisperseduniformlyintheLDPEmatrix,asindicatedbytheSEMimageinFig.1.ThePTCeffectwasobservedinallcompositematerialsduringtheheatingprocess,asshowninFig.2.Theelectricalconductivityincreasedwiththetemperature,andasharpincreaseintheconductivitywasobservedabovethecriticaltemperature.Thecompositematerialwith15wt%PTCparticlesexhibitedthehighestPTCeffect,withaconductancejumpof3ordersofmagnitudeabovethecriticaltemperatureof75℃.

ThefrictionandwearpropertiesofthecompositematerialsarepresentedinFig.3.TheneatLDPEshowedastablefrictioncoefficientofaround0.2throughoutthetest,whiletheadditionofPTCparticlessignificantlyimprovedthefrictionstabilityofthecompositematerials.Thefrictioncoefficientofthecompositematerialwith15wt%PTCparticlesdecreasedgraduallyafteraninitialspike,indicatingaself-correctingmechanismduringthePTCeffect.ThewearrateofthecompositematerialsdecreasedwiththeincreaseofPTCparticlecontent,andtheminimumwearratewasobtainedinthesamplewith15wt%PTCparticles.

TheimprovementoffrictionandwearpropertiesisattributedtotheenhancedinterfacialadhesionandtheincreasedeffectivecontactareabetweenthePTCparticlesandthepolymermatrixduringthePTCeffect.Atlowtemperature,thePTCparticlesareinsulating,andtheinterfacialadhesionbetweentheparticlesandthematrixisweak.Asthetemperatureincreases,thePTCparticlesbecomeconductive,andtheinterfacialadhesionisstrengthened,asaresultofthesurfaceroughnessoftheparticlesandthepolymermatrix.Theincreasedcontactareaandshearstrengthleadtoanimprovedloadtransferandareducedwearrate.

Conclusion:

Conductivelow-densitypolyethylene-basedcompositematerialswithPTCcharacteristicsweresuccessfullyfabricated,andtheirfrictionandwearpropertieswereinvestigated.ThePTCparticlessignificantlyimprovedthefrictionstabilityandwearresistanceofthecompositematerials,withtheoptimizedcompositionof15wt%PTCparticles.Theself-correctingmechanismduringthePTCeffectandtheenhancedinterfacialadhesionandcontactareawereresponsiblefortheimprovedproperties.TheresultssuggestthatthePTCmaterialshavepromisingapplicationsinself-regulatedfrictionandwearsystems.ThefindingsofthisstudyprovidenewinsightsintothepotentialapplicationsofPTCmaterialsinfrictionandwearsystems.Theself-regulatingpropertiesofPTCmaterialsmakethemsuitableforuseindevicesthatrequirestablefrictionandwearperformance,suchaselectronicdevices,sensors,andself-regulatedheaters.TheimprovedfrictionstabilityandwearresistanceofthePTCcompositematerialspresentedinthisstudyalsosuggestthattheymaybeusedinawiderangeofengineeringapplications,suchasincoatings,bearings,andseals.

However,furtherresearchisneededtofullyexplorethepossibilitiesofPTCmaterialsinfrictionandwearsystems.Forexample,theeffectofPTCparticlesizeandcontentonthefrictionandwearpropertiesneedstobeinvestigated.Themechanismbehindtheself-correctingbehaviorobservedduringthePTCeffectalsorequiresfurtherunderstanding.Moreover,thelong-termstabilityofthePTCmaterialsundervariousenvironmentalconditionsneedstobeevaluatedtodeterminetheirfeasibilityforpracticalapplications.

Inconclusion,thisstudydemonstratesthepotentialofPTCmaterialsasanewclassofcompositematerialsforfrictionandwearsystems.ThePTCeffectenhancestheinterfacialadhesionandcontactareabetweenthePTCparticlesandthepolymermatrix,resultinginimprovedfrictionstabilityandwearresistance.FurtherinvestigationsarerequiredtofullyexplorethepossibilitiesofPTCmaterialsinthisfieldandtodevelopnovelandadvancedmaterialsforpracticalapplications.OnepotentialareaforfurtherresearchisthedevelopmentofPTCmaterialswithtailoredpropertiesforspecificapplications.Forexample,bycontrollingthesizeanddistributionofPTCparticlesinapolymermatrix,researcherscouldcreatematerialswithdifferentthermalandelectricalconductivityproperties.Thiswouldopenupnewpossibilitiesforapplicationssuchasthermalmanagementinelectronicdevicesorsensorsthatrequirecontrolledthermalresponses.

Anotheraspectthatneedstobeinvestigatedistheeffectofloadingconditions,suchastemperatureandpressure,onthefrictionandwearpropertiesofPTCmaterials.Simulatingrealisticconditionsinwhichthesematerialswouldbeusedcanprovideinsightsintotheirperformanceandidentifyanylimitsorpotentialissuesintheirpracticaluse.

Furthermore,exploringtheuseofPTCmaterialsassolidlubricantsorcoatingscouldprovidenovelsolutionsforreducingfrictionandwearinvariousindustrialapplications.PTCparticlecoatingshaveshownpotentialforreducingfrictionandwearinmetal-matrixcomposites,andfurtherinvestigationscouldleadtothedevelopmentofimprovedcoatingsforuseinengineeringapplications.

Insummary,thedevelopmentofPTCmaterialsasanewclassofcompositematerialsforfrictionandwearsystemshassignificantpotentialfornumerousapplicationsinarangeoffields.FurtherresearchcanhelpexpandourunderstandingofthePTCeffectandidentifyopportunitiesfordevelopingadvancedmaterialswithtargetedpropertiesforspecificapplications.ThepromisingpropertiesofPTCmaterialssuggestthattheymayofferinnovativesolutionsforimprovedfrictionandwearperformanceinnumerousindustrialandtechnologicalapplications.AnotherimportantareaforfurtherresearchistheimprovementoftheprocessingtechniquesusedtomanufacturePTCmaterials.Currently,manyfabricationmethodsrelyonhighshearmixingprocesses,whichcancauseexcessiveparticlebreakageandagglomeration,resultinginreducedmaterialproperties.DevelopingmorecontrolledandscalableprocessingmethodscouldhelptomitigatetheseissuesandimprovethereproducibilityandconsistencyofPTCmaterials.

Additionally,investigatingthelong-termstabilityandagingbehaviorofPTCmaterialsisvitaltoensuretheirsuitabilityforuseinreal-worldenvironments.Exposuretotemperaturecycles,moisture,andchemicalinteractionscanallaffectthepropertiesandperformanceofPTCmaterials,andunderstandingtheirbehaviorundersuchconditionscanaidindevelopingmorerobustanddurablematerials.

Finally,exploringthepotentialforusingPTCmaterialsinnovelapplications,suchasenergyharvestingandstorage,couldopenupexcitingnewopportunitiesforthesematerials.PTCmaterialshavebeenshowntohavehighthermoelectricconversionefficiency,makingthempromisingcandidatesforuseinenergyharve