生物可降解聚乳酸基纳米复合材料的热性能和结晶动力学研究

河南大学硕士学位论文生物可降解聚乳酸基纳米复合材料的热性能和结晶动力学研究姓名：郭有钢申请学位级别：硕士专业：高分子化学与物理指导教师：张普玉2011-06IPLLARNSDNSNLY101ICaCO3Vinyl-POSS/RNS1.PLLATGADSCX-XRDFTIR1%PLLA-NH2SiO2RNS-CH3SiO2DNSPLLAVinyl-POSSPLLANLY101ICaCO3PLLAPLLAII2.PLLA/RNSDSCAvramiRNSPLLARNSPLLAKt1/2AvraminRNSPLLAArrheniusLauritzen-HoffmanEKgσeEKgσeRNSPLLA3.RNS/PLLADSCXXRDRNSPLLAJeziornyMoRNSPLLAKissingerERNSRNSPLLARNSAvramiJeziornyMoPLLAJeziornyMoAugis-BennettTakhorKissingerRNSPLLARNSIIIABSTRACTPoly(lacticacid)orPolylactide(PLA)isthemostextensivelyresearchedandutilizedbiodegradableandbiocompatiblethermoplasticaliphaticpolyester,producedfromrenewableresources,andenvironmentallybenignmaterial,whichattractsmanyresearcherstowidelyresearch.Becauseofitsfavorablebiodegradability,highstrengthandstiffness,transparency,nontoxictothehumanbodyandtheenvironment,aswellasincontrasttothoseconventionalplastics,PLAhasexcellentpotentialforsubstitutionofpetroleum-basedpolymers.AlthoughPLAisaneco-friendlybioplasticwithexcellentbiocompatibility,processibility,andlessenergydependence,ithasdrawbacksaswell,suchasitspoortoughness,lowheatdistortiontemperature,slowcrystallizationrateanddegradationrate,hydrophobicity,unsatisfactorygasbarrierproperties,lackofreactiveside-chaingroups,whichlimitsitsdevelopmentandwidepracticalapplication.Therefore,severalmodificationshavebeenproposedtoovercometheaforementionedproblemsofPLA.Themainmodificationmethodsincludepolymerblending,copolymerizationandcompositingwithsomenano-materials.Amongtheseveralmodifications,compositingwithsomenano-materialsareregardedasausefulandconvenientway.Nanoscalefillersweredispersedintothematrixofpolylactidetoformpolylactide-basednanocomposites,whichcouldsignificantlyimprovethemechanicalproperties,gasbarrierproperties,thermalpropertiesandbiodegradablepropertiesofPLA.Thetechniquehadattractedgreatattentionbothinindustryandinacademiaathomeandabroad.Inthisarticle,thenanocompositesbasedonPoly(L-lactide)(PLLA)andnanoparticalecontainedreactablenano-SiO2(RNS),dispersiblenano-SiO2(DNS),nano-CaCO3(brandname:NLY101I)andVinyl-polyhedraloligomericsisesquioxane(Vinyl-POSS)werepreparedthroughultrasound-assistedmeltblendingmethod,thethermalpropertiesofPLLAanditsnano-compositeswerestudied;PLLA/reactablenano-SiO2nanocompositeswerepreparedbyinjectionmoldingmethodandisothermalcrystallizationkineticsandnon-isothermalcrystallizationkineticsofPLLAandPLLA/reactablenano-SiO2nanocompositeswerestudied.Themainworkinthispaperisasfollows:1.Poly(lacticacid)wasmodifiedwithdifferentnanoparticlesviaultrasound-assistedmeltblendingmethod.ThethermalpropertiesofPLLAanditscompositeshasbeeninvestigatedusingthermo-gravimetricanalysis(TGA),differentialscanningcalorimetry(DSC),X-raydiffraction(XRD)Fourier-transforminfrared(FTIR).TheresultsindictedthatthethermalstabilityofPLLAaffectedbysameconcentration(1%)ofdifferentnanoparticlesweredifferent.ThethermalstabilityofPLLAwasincreasedbyjoiningnano-SiO2with—NH2(RNS)and—CH3(DNS)functionalgroup.TheadditionofVinyl-polyhedraloligomericsisesquioxane(Vinyl-POSS)hadlittleinfluenceonthethermalstabilityofPLLA.WhilenanoCaCO3(brandname:NLY101I)iscausedsignificantreductioninthermalstabilityofPLLA.Moreover,theadditionsofdifferentnano-particleshavehadimpactoncoldcrystallization,meltingIVandcrystallization.2.PLLA/reactablenano-SiO2nanocompositeswerepreparedbyinjectionmoldingmethod.TheisothermalcrystallizationbehaviorofPLLAanditscompositeswasstudiedwithdifferentialscanningcalorimetry(DSC)andtheeffectofnano-SiO2wasexplored.ThecrystallizationKineticsunderisothermalconditionswasdescribedbytheAvramiequation.Itshowedthatreactablenano-SiO2(RNS)hadthefunctionofheterogeneousnucleationtoPLLAmatrix.WithincreasingRNScontent,thecrystallizationrateofPLLAmatrixwasincreasedandthehalf-timecrystallizationofPLLAanditsnanocompositeswasdecreased,buttheAvramiexponentnhadnosignificantchange,whichindicatedthatRNShadn’tchangedthenucleationmechanismofPLLA.Inaddition,theArrheniusequationandthefamousLauritzen-HoffmannequationwereappliedtodescribetheactivationenergyEandthenucleationparameterKgandtheendsurfaceenergiesσeofPLLAanditsnanocomposites.TheresultsrevealedthattheactivationenergyofthenanocompositeswassmallerthantheactivationenergiesofthepurePLLA.ThevaluesofKgandσefornanocompositeshaveincreasedslightlycomparedwithpurePLLA.ItindicatedthattheactivationenergiesofPLLAnanocompositeswerereducedbyaddingRNS,withtheresultthatRNSpromotedeffectivelythecrystallizationofPLLAmatrix.3.Poly(L-lactide)(PLLA)/reactablenano-SiO2(RNS)nanocompositeswerepreparedbyinjectionmoldingmethod.ThemeltingcrystallizationandcoldcrystallizationbehaviorofPLLAanditsnanocompositeswerecharacterizedbyDifferentialScanningCalorimetry(DSC)andX-RayDiffraction(XRD)measurements.ThedynamicmechanicalPropertiesofPLLA/RNSnanocompositeswerealsoinvestigated.ThemicrophotographsofPLLA/RNSnanocompositeswereinvestigatedwithTransmissionElectronMicroscopy(TEM).TEMimagesindicatedthatRNSnanoparticleswerehomogeneouslydispersedinthePLLAmatrix.ThenonisothermalmeltingcrystallizationandcoldbehaviorofthePLLAanditsnanocompositeswa