简介:ThecopolymerswereformedbythegraftcopolymerizationofPVCwithacrylicrareearth.TheprincipleandmethodofthegraftcopolymerizationofPVCandacrylicrareearthwerediscussed.ThegraftcopolymerswerecharacterizedbyFT-IRspectraandscanningelectronmicroscope(SEM).Thethermalstabilityofthegraft-copolymerswasstudiedbythermogravimetricanalysis(TG).Theexperimentresultsshowthatthethermalresistanceandtoughnessofthegraftcopolymersareobviouslyenhanced.
简介:Surfacemodificationonapolytetrafluoroethylene(PTFE)panelwasperformedwithsequentialnitrogenplasmatreatmentsandsurface-initiatedpolymerization.ByintroducingCOO—groupstothesurfaceofthePTFEpanelthroughgraftingpolymerizationofacrylicacid(AA),atransparentpoly(acrylicacid)(PAA)membranewasachievedfromacrylicacidsolution.GraftingpolymerizationinitiatingfromtheactivegroupswasachievedonthePTFEpanelsurfaceafterthenitrogenplasmatreatment.Utilizingtheacrylicacidasmonomers,withCOO—groupsascrosslinksitestoformreticulationstructure,atransparentpoly(acrylicacid)membranewitharborescentmacromolecularstructurewasformedonthePTFEpanelsurface.Analysismethods,suchasfouriertransforminfraredspectroscopy(FTIR),microscopyandX-rayphotoelectronspectroscopy(XPS),wereutilizedtocharacterizethestructuresofthemacromoleculemembraneonthePTFEpanelsurface.AcontactanglemeasurementwasperformedtocharacterizethemodifiedPTFEpanels.ThesurfacehydrophilicitiesofmodifiedPTFEpanelsweresignificantlyenhancedaftertheplasmatreatment.Itwasshownthatthegraftingrateisrelatedtothetreatingtimeandthepowerofplasma.
简介:Aseriesofacrylic-basedsuperabsorbentresinsweresynthesizedbyinversesuspensionpolymerization,usingpotassiumpersulfateastheinitiator,N,N′-methylenebisacrylamide(BIS)anddivinylbenzene(DVB)asthemultiplecrosslinkingagents.ThemorphologyoftheresultingsuperabsorbentresinsrevealedbySEMdemonstratedthatahardshelllayerwasindeedformedduetosurfacecrosslinking.Theswellinganddeswellingproperties,andthemechanicalstrengthofsuperabsorbentswereinvestigated.TheresultsindicatedthattheaddingtimeofDVBandtheamountofDVBparticipatedinthecrosslinkingshowasignificantinfluenceonthepropertiesofsuperabsorbents.WhenDVBwasaddedinpolymerizationlater,theamountofDVBparticipatedinreactiondecreasesandthesurfacecrosslinkedshellbecomesthinner.ItissuitableforDVBtobeintroducedinthelaterstageofthepolymerizationprocess,becausetheabsorptionrateofresinisefficientlyimprovedinconjunctionwithhigherwaterabsorption.Furthermore,itwasfoundthatthemechanicalstrengthofswollensuperabsorbentwithsurfacecrosslinkingwasindeedenhancedincomparisonwiththatoftheconventionalone.
简介:Inordertostudytheflammabilityandexplosionpropertyofgasesduringthepropaneoxidationtoacrylicacidprocess,theexplosionlimitsandthesafetyoxygencontentofgasesattherecyclegascompressoroutlet,thereactorinlet,andthereactoroutletweretheoreticallycalculatedandexperimentallytested.Finally,theinertlimitwasalsodetermined.Itshowedthatgasesattherecyclegascompressoroutletandthereactoroutletwerenonflammablebasedonthreeindicators:theexplosionlimits,thesafetyoxygencontentandtheinertlimit.TheC3H6andO2contentswerehigheratthereactorinlet,whichmadethemixedgaseseasilyignitable.However,thelargeamountofinertgasessuppressedthepossibilityofexplosioneffectively.Asaconsequence,noexplosionphenomenonwouldhappeninallthreelocations.Butgasesatthereactorinletaremostdangerous,wheremoresupervisionontheconcentrationofgasesandmorestrictcontrolonthetemperatureandpressureshouldbeimplemented.Besidesthis,openflame,hotsurfacesandothersourcesofignitionareprohibitedinworkingspaces.Theexperimentalresultscanbeappliedtosimilarprocessforoxidationofpropane.
简介:Bilayerhumidity-responsiveactuatorsaregenerallycomposedofactuatingandsupportinglayersofdifferentmaterialswithlargelydifferentwettability.Suchkindsofbilayeractuatorssufferfromlowadhesiveforcebetweenthetwolayersduringusage.Thisstudydemonstratesthepreparationofhumidity-responsivebilayeractuatorsthathavethesamematerialsintheactuatingandsupportinglayerstoavoidtheadhesiveissue.Thebilayeractuatorsconsistofaporouspoly(acrylicacid)σAA)/poly(allylaminehydrochloride)(PAH)layerandanonporousPAA/PAHlayerthatarefabricatedbyexponentiallylayer-by-layerassemblymethod.Atahigh/lowrelativehumidity(RH),thenonporousPAAIPAHlayercanefficientlyexpand/shrinkbyabsorbing/desorbingwaterwhilethevolumeexpansion/shrinkageoftheporousPAA/PAHlayerinanenvironmentwithchangedhumidityissignificantlysuppressedbythemicrometer-sizedpores.Thelargelydifferentexpansion/shrinkageofthenonporousandporousPAA/PAHlayerswhensubjectedtohumiditychangesenablesrapidandreversiblerolling/unrollingmotionsofthebilayeractuator.Thebilayeractuatorshowsafasterrollingspeedandalargerbendingcurvaturewhensubjectedtoalargerhumidityincrease.