专业英语 Unit 6教案学习资料

UnitSixCONVENTIONALCOMPOSITERESINIndentistrythetermform,“composite”initiallyreferredtoarestorationmaterial,usuallyinpasteform,consistingofanorganicbindercontainingatleast60percentinorganicfillerbyweightincorporatedintoasystemthatwouldinducepolymerization.Likewise,thefillerparticlesarecoatedwitha“coupling”agenttobondthemtheresinmatrix.Thus,theessentialsofacompositearearesinbinder,afillerandacouplingagent.Anumberofparametershaveamarkedinfluenceuponthepropertiesthatcanbeobtainedbytheadditionoffillerstoaresinmatrix.Thecharacterizationofthedispersedphaseintermsofitsshape,size,hardness,concentrationanddistributionisveryimportant.Thecompositionofthecompositionofthecontinuousphase,i.e.,theresinmatrix,isequallysignificant.Thusthetermcompositedistinguishesthisclassofmaterialsfromtheunreinforceddirectacrylicfillingresins,includingthosematerialstowhichsmallamountsofafillerhavebeenadded.ResinMatrixThedimethacrylatemonomer(BIS-GMA)isthechiefcompositionofresinmatrix.Itcanbesynthesizedbythereactionbetweenbisphenol-Aandglycidylmethacrylate.Italsocanbeobtainedbythereactionofglycidyletherofbisphenol-Aandmethacrylicacid.Thishybridmoleculeisclassifiedasathermo-settingmethacrylateresin.Ithasprovedtobesuitableforuseasabinderforreinforcingfillers.Ithasasomewhatlowerpolymerizationshrinkagethandoesmethylmethacrylateandhardensrapidlyunderoralconditions.Theresinforthematrixofcommercialcompositeresinsmustbemodifiedinordertoimprovecertainproperties.Thedimethacrylateresinistooviscousforconvenientuseatambienttemperatures,soitisdilutedbytheadditionofothermethacrylatemonomersoflowviscosity.Thesemonomersmaybedifunctionalsoastoformacross-;inkedpolymer.Stabilizersareaddedtoimproveshelflife.Sincepolymerizationisgenerallyaccomplishedbymeansoftheperoxide-aminesystem,ultravioletlightabsorbingcompoundsmustbeaddedtominimizecolorchangeinthematerialwhenexposedtosunlight.Mostoftheconventionalcompositesarechemicallyactivatedviatheperoxide-amineinitiationsystem.Thetwopastesareidenticalexceptthatonecontainsthebenzoylperoxidetheotherthetertiaryamineactivatororaccelerator.Whenthetwopastesaremixedtogetherthematerialpolynierizes.Lightcuredsystemsareemployedinthecurrentlypopularcomposites.FillersThefillerinacompositemustbeinhighconcentrationifthedispersedparticlesaretoinhibitdeformationofthematrix.Also,anotherfunctionofthefilleristoreducethecoefficientofthermalexpansionoftheresinmatrix.Althoughthefillerconcentrationvariesfromonecommercialproducttoanother,itisgenerallypresentintheamountof70to80percent.Conventionalproductsmostoftencontaincrystallinequartzand/orlithiumglassceramics,however,otherfillers,suchascalciumsilicate,glassbeadsandglassfibershavebeenused.Assomeradiopacityisdesirableinarestoration,thisisachievedbyfillerblendscontainingbariumandstrontiumglassesandmostrecentlylanthanumglass.Particlesizedistributionisanimportantconsiderationforthefiller.Inmostconventionalcomposites,thedistributionrangesfromlto100blicrometers.Generally,blendsoffineparticles(l-20pm)andcoarseparticles(<100um)areemployed.CouplingAgentsAstable,adhesivebondingofthefillertotheresinisessentialforstrengthanddurabilityinthecomposite.Thus,themanufacturescoatthesurfaceofthefillerwithasuitablecouplingagent.Suchagentsmayalsoactasastressabsorberatthefiller-resininterface.Vinylsilanecouplingagentswerefirstused.Thesehavenowbeenreplacedbymorereactivecompounds,suchasA-174(methacryloxypmpyltrimethoxysilane).VOCABULARYl.Composite复合树脂dentalcompositeresin牙科复合树脂dentalcompositerestorativematerials牙科复合树脂充填材料2.conventionalcomposite传统(型)复合树脂traditionalcomposite传统(型)复合树脂3.microfilledcomposite微细填料(型)复合树脂4.hybridcomposite混合填料(型)复合树脂5.organicbinder有机粘合(结)剂6.inorganicfiller无机填料7.polymerization聚合作用8.couplingagent偶联剂9.resinmatrix树脂基质10.dispersedphase分散相11.continuousphase连续相12.unreinforced未增(补)强的13.reinforced(被)增(加)强(了)的(例:reinforcedplastics增强塑料)14.directacrylicfillingresins丙烯酸酯类直接充填树脂15.unfilledacrylicresins不合填料的丙烯酸酌类树脂16.dimethacrylate甲基丙烯酸双酯17.monomer单体18.polymer聚合体(物)19.synthesize或synthesise合成，缩合(处理)20.synthesis合成(法)，缩合，拼合21.bisphenol-A双酚A22.glycidyl缩水甘油基23.methacrylate甲基丙烯酸酯24.glycidylmethacrylate甲基丙烯酸缩水甘油酯25.glycidylether缩水甘油醚26.methacrylicacid甲基丙烯酸27.thermosetting热固(凝)的，加热成型后即硬化的thermo-settingresin热固性树脂28.thermoplastic热塑(性)塑料；热塑性的，加热软化的thermoplasticresin热塑性树脂29.plymerizationshrinkage聚合收缩30.methylmethacrylats甲基丙烯酸甲酯31.viscous粘(性，滞，稠)的32.viscosity粘度33.ambient环境的，外界的ambienttemperature环境温度，室温34.difunctionalmonomer含双官(功)能团的单体35.cross-linked交联的36.subilizer稳定剂37.shelflife保存期38.pemxide-amineinitiationsystem过氧化物—胺引发体系39.benzoylperoxide过氧化苯甲酰40.initiator引发剂41.tertiaryamine叔胺42.activator活化剂43.accelerator促进剂44.lightcuredsystem光固化体系45.coefficientofthermalexpansion热膨胀系数46.radiopacityX线阻射