ASTM_D_3168_-_85_2016.pdf

Designation:D316885(Reapproved 2016)Standard Practice forQualitative Identification of Polymers in Emulsion Paints1This standard is issued under the fixed designation D3168;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This practice describes a procedure for the qualitativeidentification in emulsion paints of most types of polymerspresent as major components of the paint vehicle.Limitationsare discussed in Sections 5 and 10.1.2 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:2D16 Terminology for Paint,Related Coatings,Materials,andApplicationsD1193 Specification for Reagent WaterD2621 Test Method for Infrared Identification of VehicleSolids From Solvent-Reducible PaintsE275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers3.Terminology3.1 DefinitionsFor definitions of terms,refer to Terminol-ogy D16.4.Summary of Practice4.1 The vehicle is extracted from the dried paint and afterfiltering is cast on a salt plate.The infrared spectrum isobtained and compared with reference spectra for identificationof major components.4.2 The paint is applied to a filament and pyrolyzed todepolymerize the vehicle.An internal standard is added and thepyrolyzate is separated into its components by gas-liquidchromatography.Monomers are identified by comparison ofrelative retention times.5.Significance and Use5.1 Identification of specific acrylic polymers in emulsionpaints is often difficult or impossible by infrared alone.This isparticularly true when the acrylic is present in a small amountas a comonomer with vinyl acetate,or when blended withalkyds or other ester systems.If identification of an acryliccomponent is required in such a system,it may often beaccomplished by gas-liquid chromatographic analysis of thepyrolyzed paint film.The presence of a number of otherpolymers may often also be confirmed by pyrolysis since theyproduce characteristic and reproducible pyrograms.5.2 The pyrograms obtained from unknown samples vary incomplexity according to the sample composition.It is neces-sary to establish the presence or absence of as many compo-nents as possible from a study of the infrared spectra obtainedin the first part of this practice.The gas-liquid chromatographyresults may then be used to help identify any unknowncomponents present and to confirm identifications made byinfrared.6.Interferences6.1 Dibutyl maleate and dibutyl fumarate monomers are notsuccessfully recovered by this procedure.If their presence issuspected as comonomer in a vinyl acetate copolymer system,n-butyl alcohol should be found in the pyrolyzate.Thisevidence,together with the absence of butyl acrylate or butylmethacrylate monomer peaks,is an indirect indication of thepresence of one or both of these monomers.6.2 The presence of relatively low quantities of copolymer-ized acids may not be successfully established by thisprocedure,due to some unavoidable decomposition of acrylateand methacrylate esters to acrylic or methacrylic acid and thecorresponding alcohols during the pyrolysis.The infraredspectrum and an acid number determination,both run on the1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved April 1,2016.Published April 2016.Originallyapproved in 1973.Last previous edition approved in 2011 as D3168 85(2011).DOI:10.1520/D3168-85R16.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 polymer solids,may usually be relied upon to establish thepresence or absence of acid groups in the polymer.6.3 In the case where the polymer being analyzed is simple(such as a vinyl acetate-alkyl ester copolymer,or a singleacrylate-methacrylate copolymer),it might be advantageous toexamine the total pyrolyzate directly by infrared(as a solutionin carbon disulfide).7.Apparatus7.1 Spectrophotometer,recording,double-bea