ASTM_D_570_-_22.pdf

Designation:D57022Standard Test Method forWater Absorption of Plastics1This standard is issued under the fixed designation D570;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.Scope*1.1 This test method covers the determination of the relativerate of absorption of water by plastics when immersed.Thistest method is intended to apply to the testing of all types ofplastics,including cast,hot-molded,and cold-molded resinousproducts,and both homogeneous and laminated plastics in rodand tube form and in sheets 0.13 mm(0.005 in.)or greater inthickness.1.2 The values given in SI units are to be regarded asstandard.The values stated in parentheses are for informationonly.NOTE1This test method and ISO 62 are technically equivalent whenthe test specimen described in 6.2 is used.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsE456 Terminology Relating to Quality and Statistics2.2 ISO Standard:ISO 62 PlasticsDetermination of Water Absorption33.Terminology3.1 For definitions of terms that appear in this practicerelating to plastics,refer to Terminology D883.3.2 For definitions of terms that appear in this practicerelating to quality and statistics(such as precision and bias),refer to Terminology E456.4.Significance and Use4.1 This test method for rate of water absorption has twochief functions:first,as a guide to the proportion of waterabsorbed by a material and consequently,in those cases wherethe relationships between moisture and electrical or mechanicalproperties,dimensions,or appearance have been determined,as a guide to the effects of exposure to water or humidconditions on such properties;and second,as a control test onthe uniformity of a product.This second function is particu-larly applicable to sheet,rod,and tube arms when the test ismade on the finished product.4.2 Comparison of water absorption values of various plas-tics made on the basis of values obtained in accordance with8.1 and 8.4 have been found useful.4.3 Ideal diffusion of liquids4into polymers is a function ofthe square root of immersion time.Time to saturation isstrongly dependent on specimen thickness.For example,Table1 shows the time to approximate time saturation for variousthickness of nylon-6.4.4 The moisture content of a plastic is very intimatelyrelated to such properties as electrical insulation resistance,dielectric losses,mechanical strength,appearance,and dimen-sions.The effect upon these properties of change in moisturecontent due to water absorption depends largely on the type ofexposure(by immersion in water or by exposure to highhumidity),shape of the part,and inherent properties of theplastic.With nonhomogeneous materials,such as laminated1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.50 on Durability of Plastics.Current edition approved Sept.1,2022.Published September 2022.Originallyapproved in 1940.Last previous edition approved in 2018 as D570-98(2018).DOI:10.1520/D0570-22.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.4Additional information regarding diffusion of liquids in polymers can be foundin the following references:(1)Diffusion,Mass Transfer in Fluid Systems,E.L.Cussler,Cambridge University Press,1985,ISBN 0-521-29846-6,(2)Diffusion inPolymers,J.Crank and G.S.Park,Academic Press,1968,and(3)“Permeation,Diffusion,and Sorption of Gases and Vapors,”R.M.Felder and G.S.Huvard,inMethods of Experimental Physics,Vol 16C,1980,Academic Press.*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 StatesThis international standard was developed in accordance with internationally