ASTM_D_5946_-_09.pdf

Designation:D594609Standard Test Method forCorona-Treated Polymer Films Using Water Contact AngleMeasurements1This standard is issued under the fixed designation D5946;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method covers measurement of the contactangle of water droplets on corona-treated polymer film sur-faces.NOTE1This test method is identical to ISO 15989.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD724 Test Method for Surface Wettability of Paper(Angle-of-Contact Method)(Withdrawn 2009)3E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:4ISO 15989 PlasticsFilm and SheetingMeasurement ofWater-Contact Angle of Corona-Treated Films3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 static contact angle,(degrees),nthe angle betweenthe substrate surface and the tangent line drawn to the dropletsurface at the three-phase point,when a liquid drop is restingon a plane solid surface.3.1.1.1 DiscussionContact angle values can be deter-mined as follows:(1)by analyzing an image of a droplet usingvarious projection or reflective devices and measuring thecontact angle directly with a protractor by using tangentialalignment of a cursor line or the use of reference alignmentprocedures(Test Method D724);or(2)by analyzing an imageof a droplet using various projection or reflective devices andmeasuring the height and width on the substrate surface tocalculate the contact angle as follows:5 2arctanH/R!(1)where:=contact angle,H=height of a droplets image,andR=half its width.3.1.1.2 DiscussionInstrumentation is also available thatutilizes an image and directly determines the contact anglebased on the calculation shown for Method(2)of U.S.PatentNo.5,268,733.3.1.1.3 DiscussionMethod(1)may be biased due to thesubjective nature of visually finding a tangent to the dropletimage at the three-phase point;if Method(1)is to be used,thebias of each operators measurements shall be determined.Because Method(2)utilizes measured dimensions of the1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.19 on Film,Sheeting,andMolded Products.Current edition approved April 1,2009.Published April 2009.Originallyapproved in 1996.Last previous edition approved in 2004 as D5946-04.DOI:10.1520/D5946-09.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 droplet,it would be expected to have less bias.Comparativeanalyses using these various procedures have not been con-ducted.Therefore,caution is recommended when comparingdata obtained from these different methods.3.1.1.4 DiscussionMethod(2)may not be applicable inspecial cases in which the contact angle is greater than 904.Summary of Test Method4.1 In this test method,drops of water are placed on thesurface of a film sample,and the contact angle values aremeasured and then averaged.5.Significance and Use5.1 The ability of polymer films to retain inks,coatings,adhesives,etc.is primarily dependent on the character of theirsurfaces and can be improved by one of several surface-treating techniques.The electrical discharge treatment,such ascorona treatment,has been found to increase the wettingtension of a polymer film.The stronger the treatment,the moreactively the surface reacts with different polar interfaces.It istherefore possible to relate the contact angle of a polymer filmsurface to its ability to accept and retain inks,coatings,adhesives,etc.,if the ink,coating,or adhesive contains thepolar functionalities.Contact angle in itself is not a completelyacceptable measure of ink,coating,or adhesive adhesion.5.2 The wetting tension of a polymer film belongs to agroup of physical par