北京大学高分子辐射化学17

电离辐射技术在特种高分子辐射加工中的应用ThirteenRadiationprocessingofbiodegradablepolymersRadiationprocessingofPTFEApplicationofradiationtechniqueinSiCmaterialsTopicsRadiationprocessingofbiodegradablepolymersBiodegradablepolymersNaturalpolymersAliphaticPolyestersfrombiofermentationandchemicalsynthesesCycleofNaturalPolymersinEnvironmentCelluloseStarchChitin/chitosanSynthesisProcessingBiodegradableproductCarbondioxideWaterCompostingDisposalUseDegradationDigestionPlantGrowthPhotosynthesisMicro-organismBiodegradablePolyestersPoly(butylenesuccinate-co-adipate)Poly(butylenesuccinate)Poly(-caprolactone)Poly(L-lacticacid)RadiationcrosslinkingofPCLHOOOCH2CH2CH2CH2CH2CRnTg:-60oCTm:60oC(Problem,lowprocessingtemperature)Tensilestrength:10~30MPaElongationatbreak:300~600%RadiationcrosslinkingofPCLwithcrosslinkers图PCL在不同多官能团单体敏化下的交联情况聚乙二醇二甲基丙烯酸酯(2G,4G);三羟甲基丙烷三甲基丙烯酸酯(TMPT);四羟甲基甲烷四丙烯酸酯(A-TMMT);三甲代烯丙基异氰脲酸酯（TMAIC）Dose/kGy凝胶含量/%三甲代烯丙基异氰脲酸酯（TMAIC）的敏化效果最好，在室温下于PCL中加入1%TMAIC，50kGy的辐照就能得到凝胶含量高达80%的交联的PCL。PropertiesofcrosslinkedPCL温度/oClg(E’/Pa)图PCL辐照前后的动态弹性模量Mw:50000,未辐照,100kGy,200kGy,300kGy（1）PCL辐射交联后的弹性模量略微升高。(2)辐照以后PCL的弹性模量迅速下降的温度(失强温度)有所提高,辐照300kGy的PCL和未辐照时相比模量开始下降的温度提高近20℃。（3）辐照300kGy的PCL在较高温度时,其模量下降3～4个数量级后,显示出一个平台,仍保有一定的强度。这说明PCL在辐照较高剂量后,加热到其熔点以上,不再熔融,而是表现出高弹态的性能.ShrinkingmaterialsImprovementofPLAbyRadiation○Biodegradable○Highstrength○VeryhardPoly(lacticAcid),(PLA)○EnvironmentallyFriendlyPlastic○MedicalfieldApplicationProblemImprovementofheatresistancebyinducingcrosslinkingstructure◎Deformationabove60℃◎Difficulttosterilizeat121℃VariouscrosslinkerTAICTMAICTMPTA(H2C=CHCO2CH2)3CC2H5TMPTMA[(H2C=C(CH3)CO2CH2]3CC2H5ThreefunctionalmomomersHDDAH2C=CHCO2CH2(CH2)4-CH2COOCH=CH2TEGDAH2C=CHCO2(C2H4O)4COCH=CH2DEGDMH2C=C(CH3)CO2(C2H4O)2COC(CH3)C=CH2TwofunctionalmonomersNon-meltevenat200℃CrosslinkingofPLAKneadingwithPLAandTAICPolymerchainTAICEBirradiationHeatstability：Deformationabove60℃Structure:-(-OC(CH3)HCO-)n-CrosslinkingPolyfunctionalMonomerTriallyisocyanurate（TAIC)CNCNCNOOOCH2CCH2HCH2CH2CHCH2CCH2HFlowchartofProcessingBiodegradablePolymers,PLAKneading,180C,10minPolyfunctionalMonomersIrradiation(EB2to3MeV)Press,150C,6minFilmthickness:0.5-1.0mmEffectofTAICconcentrationonPLAcrosslinking0204060801000204060Dose(kGy)3wt%1wt%電子線照射（真空中、室温）Gel%PromotionofcrosslinkingOriginalPLAIrrad.ImmersionRemovalofuncrosslinkedpartDryingGelpartGelfraction＝OriginalGelCrosslinkedPLASolventEvaluationofcrosslinkedPLA050100150200ポリ乳酸ポリ乳酸+橋かけ助剤3wt%0402060○Findoutcrossliker,TAICforPLA○Improvementofheatresistance・Withoutdeformationevenat120℃・Keepshapeabovemeltingpoint,160℃○3wt%isbetterforimprovementofheatresistancePurePLAPLA/3%TAICTemperature(℃）Deformationrate(%)0204060800255075100125150Decreaseinweight,%PLA50kGyPLA+TAIC3wt%50kGyBiodegradabilityofcrsslinkedPLACondition:Enzyme：ProteazeKBuffer：50mM-Tris-HClpH8.5、37℃EnzymaticdegradationReactiontime(h)PLA,0kGy(a)Expandat200℃andcoolingRe-heatingat160℃forshrinkingCrosslinkedPLACrosslinkedPCLafterexpanding(b)IrradiationBeforeshrinkingHeat-shrinkableat160℃(d)(c）ShrinkabletubeofPLAHeat-resistantpropertyofcrosslinkedPLAbyirradiationUnirradiatedAfter10minat100CIrradiatedUnirradiatedIrradiated100C10minHeatinginovenAfter10mininovenat100C,•Non-crosslinkedPLA:LowTransparency(unirradiated)•CrosslinkedPLA:HighTransparency(irradiated)DeformationAfterHeatingHeatingWhycrosslinkedPLAkeptthetransparency?UnirradiatedAfter10minat100CIrradiated100C10minRecrystrizationNorecrystrizationCrosslinked(Irradiated)Non-crosslinked(Unirradiated)CrosslinkingpointRadiationprocessingofPTFEIntroductionofPTFE聚四氟乙烯（PTFE）是白色蜡状的热塑性塑料，是一种具有优良综合性能的新型工程塑料，素有“塑料王”之称。PTFE具有以下优点：（1）极好的耐热、耐寒性，适应在-180~250oC范围内长期使用；（2）高度的电绝缘性，不受环境条件的影响，属于C级绝缘材料；（3）突出的表面不粘性，几乎所有的粘性物质都不能附其表面；（4）良好的润滑性，摩擦系数为0.13，是无油润滑的理想材料；（5）耐大气老化性好，长期暴露于大气中、表面和各项性能均保持不变。氟塑料制品的用途包括以下几个方面：在化工制药工业方面，主要用于耐腐蚀的化工设备衬里、管衬、热交换器，管配件、密封垫片等在耐磨、密封方面主要用作填料密封圈、活塞等；在电气、电子工业上用作高频电缆、电机沟槽、电容器绝缘、电器接插件、印刷线路板等；在建筑业上，用作桥梁、隧道、大型屋架、管道支撑作位移用的支撑滑块；在纺织业上用作防粘辊筒；在食品工业上用作脱模材料。SuperfinepowderofPTFEpreparedbyradiationdegradation剂量/kGy050100150200300400600Mw10-45992.672.532.463.281.871.821.77表1在常温下γ辐照对PTFE超细粉分子量的影响剂量/kGy平均粒径/μm025.75020.315019.530016.360016.7表2在常温下γ辐照对PTFE超细粉平均粒径的影响SuperfinepowderofPTFEpreparedbyradiationdegradation在日本、美国、德国、意大利、荷兰等国采用辐射降解制备PTFE超细粉已有工业化生产.PTFEDegradationusingEB•OptimizedconditionsforPTFEdegradation•Molecularweightreductionto104-105Dalton•ConventionalGrindingmechanism•Microfinepowder(10micron)Radiation-inducedCrosslinkingofPTFECCFFFFnMeltingtemperature327℃Molecularweight106～107ChemicalstructureofPTFEBackgroundPTFEhasbeenclassifiedasatypicalpolymerthatundergoesmainchainscissionbyirradiation.NewtechnologyNewmaterialNewapplicationsCrosslinkedPTFEPolymerelectrolytemembraneHighperformancesealantFillerfreePTFEproductsMedicalproducts,andsoonIrradiationat340℃underoxygen-freeCrosslinkingofPoly(tetrafluoroethylene)-IrradiationVessel-CrystallinephaseAmorphousphaseCrosslinkingpointStructuralchangeTeflon(Polytetrafluoroethylene,PTFE)CrosslinkedbyHigh-TemperatureIrradiationsJ.Sunetal.(1994)340ºCrays←60Co10002003