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VCM的物化特性.doc

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PhysicalandChemicalProperties VinylChlorideMonomer(VCM) Vinylchloridemonomer(VCM),bp–13.4°C,isagasatroomtemperatureandpressure.Therefore,itishandledasacompressedvolatileliquidinallpolymerizationoperations.Itsvaporpressureoverthetypicalpolymerizationtemperaturerangeof50°to70°Cis800–1250kPa.AsaresultPVCpolymerizationreactorsarethick-walledjacketedsteelvesselswithapressureratingof1725kPa.VCMisslightlysolubleinwater(0.11wt%at20°C).Whilstthishassomeinfluenceonthesuspensionpolymerizationprocessitiscriticallyimportanttothesuccessoftheemulsionpolymerizationprocess.ThepolymerizationofVCMisstronglyexothermic,anditsspecificheatandheatofevaporationof1.352kJkg–1K–1and20.6kJ/mol,respectively,allowtheuseofacondensertoremovetheheatofreactionaswellasbythemoreconventionaljacketedvesselsystems.Itsexplosivelimitsinairare4–22vol%andplantdesign,particularlywhenhandlingunreactedVCMintherecoverysystem,mustbedesignedandoperatedaccordingly. Poly(VinylChloride)(PVC) PVCisneverusedalone.Itisalwaysmixedwithheatstabilizers,lubricants,plasticizers,fillers,andotheradditivestomakeprocessingpossible,allofwhichcaninfluenceitsphysicalandmechanicalproperties.WhentheamountofadditivesinPVCislessthen10%,thePVCiscalledunplasticized.TheplasticizedPVCvaryinchemistryandphysicalproperties,whichisdependingontheplasticizercontent. PVChasextremelygoodchemicalresistancetoallbutlowmolecularmasschlorinatedsolvents.Therefore,itiswidelyusedintheconstructionandliningofchemicalplants. HowtoidentifyPVC PurePVCturnsblueonheatingwithmonochloroaceticacidandreddish-violetwithdichloroaceticacid. ColorreactionofpolyvinylChlorideanditscopolymers(formationofpolyeneswitheliminationofHCl): Dissolveafewmgofthesubstanceinalittlepyridine,bringtotheboilfor1minandaddca.1mL2%ethanolicNaOH.IfPVCispresentthenabrowntoblackcolorationisformed.Add1mLofasolutionof0.1gb-naphthylaminein100mLdil.Sulfuricacid(1:4)to0.1…0.5mLofthisreactionmixtureandimmediatelylayerwithafewmLamylalcohol,shakevigorouslyandallowtostandfor4hours.IfPVCwaspresenttheam