ABSTRACT
H.KAMUSEWITZ1·*andW.POSSART2 1GKSSResearchCentre,InstituteofPolymerResearch,Kantstrasse55,D-14513Te/tow,Germany 2SaarlandUniversity,Geb.22-6,P.O.Box151150,D-66041Saarbriicken,Germany
Abstract-Comparedtoanideallyflatsurface,theroughnessprofileofarealsolidresultsinanadditionaldeformation ofthetriplelineregion.ThiscanbedescribedbyGood'scontortionalenergy parameterF.Intheliterature,equalF-valuesareassumedforbothwettinganddewettingexperimentsonhomogeneoussurfaces.Herewepresentanewapproachforthemissingexperimental evaluationofthisassumption.Aseriesofethyleneglycolcontactanglemeasurementsonthreepure solids(paraffinwax,polypropyleneandpolyetherimide),eachcoveringthewholerangefrom smoothtoroughsurfaces,showthatthisassumptioniscorrectforthesematerials.Asaconsequence,Wenzel'scontactangleisobtainedasthearithmeticmeanofthecosinesofadvancingand recedingcontactanglesonagivensolid.TheadditionaldeterminationofWenzel'sroughnessfactor rbyanindependentScanningForceMicroscopystudyenablesdeterminationofYoung'scontact angleatthermodynamicequilibriumfromtheadvancingandrecedingcontactangleswithoutvaryingsolidsurfaceroughnessinthewettingexperiments.
