简介:伍德composites能通常在三部分被分类:把压成薄片的composites,混合composites和渗透的composites。每部分有它的自己的特征和罐头进一步被划分。这篇论文在中国介绍历史和木头composites的开发的国家。关于把胶水压成薄片的木材的研究是稀罕的,工业几乎不来到是。成就的一个伟人在混合composites被获得了,它是很好工业化的。scrimber上的许多研究被做了,中国研究人员正在寻找在中国开发scrimber工业的一个可行方法。中国研究人员也在学习木头塑料composites(世界和平理事会)花了那么多精力,但是它一直不由于高费用是工业化的。
简介:Collagenisthemajoracellcarofconnectivetissueproteininanimals,accountingforabout25%ofthetotalbodyproteinofvertebrates.Anessentialfeatureofthistypeofbiomaterialisthatitdegradesinbiologicenvironments,eventuallydisap-pears,andleavesnopermanentforeignresidue.Averypracticalaspectoftheuseofcollagenisitseaseofpreparationanditswidespreadoccurrenceinnature.Thus,col-lagenhasbeenemployedasabiomaterialinalmosteveryphysicalform.Forexam-ple,collagenfibrescanbeusedasasubstratefornerveregeneration,tendonligament
简介:Inthispapertheresultsofahigh-speedtensionexperimentoftheSiC_w/Alcompositehavebeenreportedandasimplifiedtheoreticalmodelhasbeendevelopedtostudythefracturemechanismofcompositesinhigh-speedtension.Thistheoreticalmodelprovidesanewexplanationfortheincreaseofdynamicfracturestrengthofcompositesinhigh-speedtension.
简介:Thedynamicmechanicalpropertiesofwoodpowder/polypropylenecompositeswithdifferentwoodcontenttreatedanduntreatedwiththecompatibilizerhavebeenstudied.Ithasbeenfoundthatadditionofwoodpowdersandthecompatibilizercanbothimprovetheviscoelasticityofcomposites.Glasstransitiontemperature(Tg)ofappropriatewoodpowder-filledcompositesdecreased.Thevalueforthestoragemodulus(G')increasedgraduallywithincreasingwoodpowdercontent.Theadditionofthecompatibiliz...
简介:ThefracturebehaviorofSiCp/A356compositeatroomandhightemperatureswasstudied.Undertensilestressconditionatroomtemperature,thefractureismostlyacombinationofthebrittlefractureofSiCparticlesandductilefractureofA356matrix.Asthetensiletemperatureincreases,thecompositechangesthemainfracturebehaviortotheseparationfractureofthebondingsurfacebetweenSiCparticlesandA356matrix.Whenthetensiletemperaturereaches573K,thefracturebehaviorofthecompositesisalmostthewholeseparationfractureofthebondingsurface,whichisthemainstrengtheningmechanismathightemperature.Underthecyclestressconditionatroomandhightemperatures,themainfracturebehaviorofthecompositesisalwaysacombinationofthebrittlefractureofSiCparticlesandductilefractureofA356matrix.However,underthecyclestressathightemperature,cyclebehaviorofthecompositeschangesfromcyclehardeningatroomtemperaturetothecyclesofteningathightemperature.
简介:Agroupofpoly(phthalazinoneethersulfoneketone)/potassium-titanate-whisker(PPSEK/whisker)compositeswaspreparedbycoprecipitationfromsolution.Thewhiskersurfacewasmodifiedusingtitanatecouplingagentpriortoblending.Thetensile,impact,morphologyandthermalpropertiesofthemouldedcompositeswereinvestigated.Themeasurementsshowedthatthetensilestrengthandimpactstrengthofthecompositesincreasedwithincreasingwhiskerscontentupto10to20phr,thereaftertheyshowedadecreaseinthewhiskerscontentreached40phr.Atthesametime,themodulusofthecompositesincreasedwithincreasingwhiskerscontent.Scanningelectronmicroscopystudiesrevealedthatthewhiskerswithinthecompositesweredisperseduniformlybytreatedwithcouplingagent.Finally,thermogravimetricanalysisshowedthattheheatresistanceofthecompositestendedtoincreasewithincreasingwhiskercontent.Theresultswereanalysedanddiscussedintermsofestablishedmodelsofthebehaviourofshort-fiberreinforcedcomposites.
简介:Inordertoimprovethemechanicalpropertiesofpolypyrrole,compositesweremadebyelectropolymerizingpolypyrroleinapolyurethanematrix.Polypyrrole/polyurethane(PPY/PU)compositefilmscontainingCLO4-,BF4-orCH3-C6H4-SO3-counterionsweremadeinavarietyofsolventsystemsandcharacterizedbySEM,electronicconductivity,FTIR,andmechanicalproperties.Compositefilmsshowingmuchgreaterfiexibilitythanpurepolypyrrolewereobtained,buttheirelectronicconductivitiesweresubstantiallylower.Measuredeonductivitiesrangedfrom0.001to8S/cm,tensilestrengthsfrom44to592psi,andelongationtofailurefrom3to70%.
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简介:ThebasestructureofinsituTiCP/Fecompositesfabricatedunderindustrialconditionwaschangedbydifferentheattreatments.Erosiveweartestswerecarriedoutandtheresultswerecomparedwiththatofwear-resistantwhitecastiron.TheresultssuggestthatthewearresistanceoftheinsituTiCp/Fecompositeishigherthanthatofwear-resistantwhitecastironunderthesanderosivewearcondition.Thewearmechanismofthewear-resistantwhitecastironwasacycleprocessthatbasesurfacewaswornandcarbideswereexposed,thencarbideswasbrokenandwearpitsappeared.WhilethewearmechanismofinsituTiCp/FecompositewasacycleprocessthatbasesurfacewaswornandTiCgrainswereexposedanddropped.ThewearresistanceofinsituTiCp/Fecompositewaslowerthanthatofwear-resistantwhitecastironundertheslurryerosivewearcondition.Undersuchcircumstance,thematerialwasnotonlyundergoneerosivewearbutalsoelectrochemistryerosionduetothecontactwithwaterinthemedium.Thewearbehaviourscanbeacombinationoftwokindsofwearandthesanderosivewearisworsethanslurryerosivewear.
简介:Fibrestressofglassfibrereinforcedpolymericcopmositesonloadisdeterminedbyusingopticalfibreasmodelfiberandbymeansoflaserinterferencemethod.Inaddition,theoriginationoffibrestressduringmouldingprocessofcompositesandtherelationbetweenfiberstressofloadedcompositesandexternalstressareexamined.Theexperimentsshowthatfibrestressisrelatedtomolecularstructureofinterfacialmaterialsandstructureofinterfaciallayers.Whenstressistransferredfrommatrixtofibre,eachinterfaciallayerhasdifferentstressgradientanddeformability.Thispropertycanbecharacterizedbyintroducinganinterfacialstresstransfercoefficientktothetwo-phasemodel.
简介:PP/claycompositeswithdifferentdispersions,namely,exfoliateddispersion,intercalateddispersionandagglomeratesandpanicle-likedispersion,werepreparedbydirectmeltintercalationorcompounding.TheeffectofclaydispersiononthecrystallizationandmorphologyofPPwasinvestigatedviaPLM,SAXSandDSC.Experimentalresultsshowthatexfoliatedclaylayersaremuchmoreefficientthanintercalatedclayandagglomeratesofclayinservingasnucleationagentduetothenano-scaledispersionofclay,resultinginadramaticdecreaseincrystalsize(lamellarthicknessandspherulites)andanincreaseofcrystallizationtemperatureandcrystallizationrate.Ontheotherhand,adecreaseofmeltingtemperatureandcrystallinitywasalsoobservedinPP/claycompositeswithexfoliateddispersion,duetothestronginteractionbetweenPPandclay.Comparedwithexfoliatedclaylayers,theintercalatedclaylayershavealessimportanteffectonthecrystallizationandcrystalmorphology.Noeffectisseenforsampleswithagglomeratesandpanicle-likedispersion,inregardtomeltingtemperature,crystallizationtemperature,crystalthicknessandcrystallinity.
简介:ThefracturetoughnessandfractureworkofAl2O3/SiCprismaticceramiccompositeswasevaluatedinthispaper,whichshowedthefractureenergywasimprovedgreatly.Basedontheobservationforcrackpropagationandfracturemorphology,thefracturebehavioroftheprismaticcompositeswasanalyzed.Inthebendingtest,thecompositesdisplayedanon-catastrophicbehaviorandagracefulfailurewithreasonableload-carryingcapability.
简介:Asystematicalsimulationhasbeencarriedoutontheindentationcreeptestonparticle-reinforcedcomposites.Thedeformation,failuremechanismsandlifeareanalyzedbythreereasonablemodels.Thefollowingfivefactorshavebeenconsideredsimultaneously:creeppropertyoftheparticle,creeppropertyofthematrix,theshapeoftheparticle,thevolumefractionoftheparticleandthesize(relativesizetotheparticle)oftheindentationindenter.Forallthecases,thepowerlawrespectingtotheappliedstresscanbeusedtomodelthesteadyindentationcreepdepthrateoftheindenter,andthedetailexpressionshavebeenpresented.Thecomputersimulationprecisionisanalyzedbythetwo-phasemodelandthethree-phasemodel.Twoplacesofthestressconcentrationarefoundinthecomposites.Oneisaheadoftheindentationindenter,wherethehighstressstateisdeducedbytheedgeoftheindenterandwilldecreaserapidlyneartoasteadyvaluewiththecreeptime.Theotheroneisattheinterface,wherethehighstressstateisdeducedbythemisfitofmaterialpropertiesbetweentheparticlesandmatrix.Ithasbeenfoundthatthecreepdissipationenergydensityotherthanastressparametercanbeusedtobethecriteriontomodelthedebondingoftheinterfaces.Withthecriterionofthecriticalcreepdissipationenergydensity,apowerlawtotheappliedstresswithnegativeexponentcanbeusedtomodelthefailurelifededucedbythedebondingofinterfaces.Theinfluencesoftheshapeoftheparticlesandthematchingofcreeppropertiesofparticleandmatrixcanbediscussedforthefailure.Withacrackmodel,thefurthergrowthofinterfacecrackisanalyzed,andsomeimportantexperimentalphenomenacanbepredicted.Thefailuremechanismwhichtheparticlewillbepunchedintomatrixhasbeenalsodiscussed.Thecriticaldiflerencesbetweenthecreeppropertiesoftheparticlesandmatrixhavebeencalculated,afteraparameterhasbeendefined.Intheviewofcompetitionoffailure
简介:Theeffectofwoodspecies(ChinesefirandPoplar),woodfibercontent(10%,25%,40%)andwoodfibersizes(16to32mesh,32-65mesh,above65mesh)onthepropertiesofthewoodfiber-Polypropylenecompositeswerestudiedinthispaper.Theresultsindicatethattheeffectofwoodfibercontentandsizeincompositeweremoreimportantthanthatofchosenwoodspecies.Comparedwithpolypropylenewithoutwoodfiber,theflexuralstrengthofthecompositesincreasedwhenaddingwoodfiberintopolypr...