lesson 8 heat stabilizers演示課件演示課件

finechemicalssurfactantsadhesivesaccessoryingredients……Accessoryingredientsplasticizersantioxidantsthermalstabilizers(heatstabilizers)lightstabilizersflameretardantlubricantantistaticagentcrosslinkingagentcouplingagent穩(wěn)定劑StabilizerInchemistryastabilizerisachemicalwhichtendstoinhibitthereactionbetweentwoormoreotherchemicals.Itcanbethoughtofastheantonymtoacatalyst.Itcanbealsoachemicalthatinhibitsseparationofsuspensions,emulsions,andfoams.Stabilizersforpolymersareuseddirectlyorbycombinationstopreventthevariouseffectssuchasoxidation,chainscissionanduncontrolledrecombinationsandcross-linkingreactionsthatarecausedbyphoto-oxidationofpolymers.Polymersareconsideredtogetweatheredduetothedirectorindirectimpactofheatandultravioletlight.Theeffectivenessofthestabilizersagainstweatheringdependsonsolubility,abilitytostabilizeindifferentpolymermatrix,thedistributioninmatrix,evaporationlossduringprocessinganduse.Antioxidant抗氧劑Thermalstabilizer熱穩(wěn)定劑Lightstabilizer光穩(wěn)定劑Thermalstabilizer熱穩(wěn)定劑（thermalstabilizer）thermalstabilizerAntioxidantTheprimaryfunctionoflightstabilizeristoprotectthesubstancefromthelong-termdegradationeffectsfromlight,mostfrequentlyultravioletlight.DifferentUVstabilizersareutilizeddependinguponthesubstrate,intendedfunctionallife,andsensitivitytoUVdegradation.LightstabilizerLesson8HeatStabilizersNewWordsandExpressionsheatstabilizer熱穩(wěn)定劑degradationn.降級,降格,退化radiationn.發(fā)散,發(fā)光,發(fā)熱,輻射,放射,放射線,放射物articlen.物品,物件antioxidantn.抗氧化劑,硬化防止劑highimpactpolystyrene高抗沖聚苯乙烯inhibitvt.抑制,約束susceptibleadj.易受影響的,易感動的,容許...的polypropylenen.聚丙烯polyvinylchloriden.聚氯乙烯polyethylenen.聚乙烯polyestern.聚酯fluorocarbonn.碳氟化合物benzophenonen.苯甲酮benzotriazolen.苯并三唑,連三氮茚acrylonitrilen.丙烯腈titaniumdioxide二氧化鈦；鈦白zincoxide氧化鋅Stabilizersprovideprotectionagainstdegradationcausedbyheat,oxidationandsolarradiation.Thus,whenusedinplasticcompositionstheymaybeclassifiedasheat(orother)stabilizers,antioxidantsandUVlightstabilizers.Itistheroleofheatstabilizerstopreventthepolymerfromdegradingduringtheshortperiodofhightemperature(150to300℃)processingandtoprotectthefinishedplasticarticleagainstslowagingoverlongerperiodsatservicetemperature.Antioxidantsinhibitorretardoxidativedegradationatnormalorelevatedtemperaturesduringprocessing,storageorservice.Mostpolymersundergosomeoxidativedegradation,buthydrocarbonpolymersareespeciallysusceptible.Antioxidantsthereforearegenerallyaddedinsmallquantities.Mostplasticsexhibitvaryingdegreesofdegradationuponprolongedoutdoorexposure.Polypropylene,polyvinylchloride,polyethylene,polyesters,crystallineandhighimpactpolystyrenes,andABSareparticularlysensitive.Otherplastics,particularlypoly(methylmethacrylate)andthefluorocarbons,aremuchmoreresistant.Toarrestorretardpolymerdegradationcausedbytheultravioletportionofsolarradiation,plasticformulationscontainUVabsorbers.Thesearecompoundssuchassubstitutedbenzophenones,benzotriazolesandacrylonitrilesthatselectivelyabsorbharmfulradiationandconvertittoheatenergy.Pigmentssuchastitaniumdioxideandzincoxidearealsousedtoprotectplasticagainsttheharmfuleffectofultravioletradiation.TheyfunctionbyabsorbingsomeUVradiation,buttheirabilitytoreflectradiation(heataswellaslight)accountsfo