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1、EvolutionofStructureandPropertiesinFiberFormationfromaThermoplasticPolyester-PolyetherSegmentedCopolymerA.S.ABHIRAMAN*andY.W.KIM,SchoolofChemicalEngineering,GeorgiaInstituteofTechnology,Atluntu,Georgia30332,andK.B.WAGENER,DepartmentofChemistry,UniversityofFlorida,Gainesville,Florida32611Syno
2、psisProcess-structure-propertyrelationshipsintheformationofanelasticfiberfromameltofsegmentedpolyester-polyethercopolymersaredescribed.The“soft”segment,polyethyleneoxide,ismodifiedtopreventitscrystallizationatusetemperatures.Featuresofthepolymerrelatedtophaseseparationofthesoftsegmentsandthe
3、crystallizable“hard“segmentsarediscussed.An“ideal”morphologyofsuchathermoplasticelastomericfiberthatwouldmaximizeitsrecoverableextensionisdefined,andapathtowarditsrealizationinameltspinningprocessisdescribed.Thermoplasticelastomersarecomposedusuallyofblocksorsegmentsofatleasttwodissimilarcha
4、insegmentsalongthepolymerbackbone.Oneofthecomponentsisnoncrystallineandisaboveitsglass-transitionrangeatservicetemperatures(softsegment)whiletheotheriseitherintheglassyorthepartiallycrystallizedstate(hardsegment).Muchresearchhasbeenconductedinrecentyearsonsynthesis,morphology,andpropertiesof
5、thesepolymers,whichderiveuniquepropertiesfromtheirtwo-phasemicrostructureofpre-dominantlyhard-andpredominantlysoft-segmentdomains.’-16Domainsofthehardsegmentsprovidethermallyreversiblephysicalcross-linksfortheelastomericsoftsegments.Awell-knownexampleisthestyrene-butadiene-styrene(SBS)blockc
6、opolymerinwhichtheglassydomainconsistingofstyreneblocksprovidesthephysicalcross-linksfortherubberybutadieneblo~ks.’~-’~Distinctionisusuallymadebetweensuch“long-block”copolymersand“segmented-block”copolymers,whichhavesequencesofalternatinghardandsoftblocksofsomewhatshorterlengths.Amongthislat
7、terclass,seg-mentedp~lyester/ethers”.~~-~~andpolyurethaneshavereceivedwidespreadattention,withextensivestudiesontheirmicrophaseseparatedmorphology.Techniquessuchassmall-anglex-rayscattering,electronmicroscopy,birefrin-gence,infrareddichroism,anddyn
