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1、GenerationofMicrocellularPolyurethaneFoamsviaPolymerizationinCarbonDioxide.I:PhaseBehaviorofPoIyurethanePrecursorsKRISTENL.PARKSandERICJ.BECKMANChemicalEngineeringDepartmentUniversityofPittsburghPittsburgh,Pennsylvania15261Oninvestigatingthegenerationofmicrocellularpol
2、yurethanefoamviareactionincarbondioxide,wehaveobservedthatcommonpolyurethaneprecursorsareCO,miscible,whereastypicallyfluorinatedcompoundsorspeciallydesignedsurfac-tantsareneededtosolubilizepolymersinCO,.BothisocyanatesandpolyolsareC0,-miscibleatworkablepressuresandtemp
3、eraturesandinusefulconcentrationstoallowgenerationofpolyurethanefoamsinCO,.Bycharacterizingthephasebehaviorofseveralseriesofpropyleneoxideandethyleneoxidepolyols,wehaveobservedthatthecombinedeffectsofmolecularweightandhydroxylnumberflxthelocationofthephaseseparationpre
4、ssures.Ingeneral,lowermolecularweightsandlowerhydroxylmolefractionsproducephaseboundariesatrelativelylowerpres-suresincarbondioxide.ItalsohasbeenshownthatC0,-solublecompoundsmayhaveacompatibilizingeffectonlessC0,-solublematerials.INTRODUCTIONinmicrocellularurethanegene
5、ration(cellsizesontheorderof1to100microns).Hereporesaregeneratedarbondioxideisanenvironmentallysoundalter-CnativetoCFC's,asitdoesnotdegradetheozonethroughaphaseseparationthatisinducedthroughlayer,nordoesithaveavolatileorganiccompoundeithermolecularweightbuilduporpressu
6、requench.(V.O.C.)designation.CO,isanonflammable,lowtox-Knowledgeofthephasebehaviorofpolyurethanepre-icity,inexpensivechemicalwhichisreadilyavailablecursorsandCO,willthusallowselectionofreaction(itistheby-productofseveralexistingindustrialpro-conditionswheretheprecursor
7、sandCO,areinitiallycesses).Intraditionalurethanefoams,carbondioxidemiscible.Thephasebehaviorofpolyurethanerawma-ispresentasthereactionproductbetweenanisocya-terialsandCO,hasnot,toourknowledge,beenin-nateandwater.Consequently,theuseofCO,asavestigatedextensively.blowinga
8、gentrequiredtheacceptanceofacertainAsignificantbodyofpreviousresearchhasfocusednumberofurealinkagesinthepolymer.Recen
