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1、polymerreviewDielectricpropertiesofpolymersatmicrowavefrequencies:areviewAnthonyJ.BurUSDepartmentofCommerce,NationalBureauofStandards,CenterforMaterialsScience,PolymersDivision,Gaithersburg,MD20899,USA(Received27August1984)Areviewofthedielectriclossspectraofpolymersatmicrowavefrequencieshasbeen
2、carriedout.Whilethemainfocusofattentionisthefrequencyrangefrom100MHzto100GHz,lossspectraoutsidethisregionarealsoreviewedbecausevariationsintemperaturecancauseashiftofdielectriclossintooroutofthemicrowaverange.Alargevolumeofdataforlowlosspolymers(polyethylene,polypropyleneandpoly(tetrafluoroethy
3、lene)),whichareusedinthecommunicationsindustry,wasavailableforreview.Otherpolymers,forwhichdatawereavailableandwhichhavesignificantlossatmicrowavefrequenciesare:polystyrene,poly(vinylchloride),poly(vinylidenechloride),poly(vinylidenefluoride),poly(methyl-methacrylate),poly(methylacrylate),poly(
4、oxymethylene),poly(ethyleneoxide),poly(propyleneoxide),polyacetylene,andpoly(sulphurnitride).Also,themicrowavedielectricpropertiesofengineeringthermoplasticssuchaspoly(phenyleneoxide),polycarbonateandpolysulphanehavebeenreviewed.Theoriginsofmicrowavedielectriclossinpolymersarecategorizedas:(a)d
5、ipolarabsorptiondispersionsinbothcrystallineandamorphouspolymers;(b)dipolarlossesduetoimpurities,additivesorfillersinapolymermaterial;(c)microwaveabsorptioninconductingpolymers(polyacetyleneandpoly(sulphurnitride))forwhichthecurrentcarriersareelectrons;and(d)photon-phononabsorptionspectracorres
6、pondingtothedensityofstatesinamorphousregionsofapolymermaterial.(Keywords:dielectricconstant;dielectricloss;microwaveabsorption;microwavefrequencies;polymers)INTRODUCTIONfoundthatitwasnotpossibletoisolateourattentiontothefewdecadesofmicrowavefrequencies.Inthepastfiftyyears,measurementsofcomplex
7、dielectricThetemperatureofthematerialmustalsobecon-constantshavebeenusedtostudyelectricalpropertiessideredbecausethelossspectrachangeinshapeandandtoelucidatethemoleculardynamicsofpolarandpositiononthefrequencyscalewithachangeintem
