1、Designation:D670121Standard Test Method forDetermining Water Vapor Transmission Rates ThroughNonwoven and Plastic Barriers1This standard is issued under the fixed designation D6701;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the
2、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.Scope1.1 This test method covers a procedure for determining therate of water vapor transmission ranging between 500 to100 0
3、00 g(m2day)through nonwoven and plastic barriermaterials.The method is applicable to films,barriers consistingof single or multilayer synthetic or natural polymers,nonwo-ven fabric,and nonwoven fabrics coated with films up to 3 mm(0.1 in.)in thickness.1.2 This test method provides for the determinat
4、ion of(1)water vapor transmission rate(WVTR),and(2)the permeanceto water vapor.1.3 The values stated in SI units are to be regarded asstandard.The values given in parentheses after SI units areprovided for information only and are not considered standard.The acceptable units for WVTR are usually g/(
5、m2day).1.4 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 u
6、se.1.5 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
7、to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD1898 Practice for Sampling of Plastics(Withdrawn 1998)3D4204 Practice for Preparing Plastic Film Specimens for aRound-Robin StudyD5729 Test Method for Thickness of Nonwoven Fabrics(Withdrawn 2008)3
8、E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF1249 Test Method for Water Vapor Transmission RateThrough Plastic Film and Sheeting Using a ModulatedInfrared Sensor3.Terminology3
9、.1 Definitions:3.1.1 water vapor permeability coeffcient,nthe ratio ofthe permeance and the thickness.3.1.1.1 DiscussionThis quantity should not be used unlessthe relationship between thickness and permeance has beenverified in tests using several thickness of the material.Thewater vapor permeabilit
10、y is meaningful only for homogeneousmaterials,in which case it is a property characteristic of bulkmaterial.An accepted unit of water vapor permeability is themetric perm centimeter,or 1 g per m2per day per mm Hg-cmof thickness.The SI unit is the mol/(m2-s-Pa-mm).3.1.2 water vapor permeance,nthe rat
11、io of a barrierswater vapor transmission rate to the vapor pressure differencebetween the two surfaces.3.1.2.1 DiscussionAn accepted unit of water vapor per-meance is the metric perm,or 1 g/m2per day per mm Hg.TheSI unit is the mol/(m2-s-Pa).Since the water vapor permeanceof a specimen is generally
12、a function of relative humidity andtemperature,therefore those conditions must be stated.3.1.3 water vapor transmission rate(WVTR),nthe steady-state time rate of water vapor flow through unit area of aspecimen,normal to the surfaces under specific conditions oftemperature and humidity at each surfac
13、e.3.1.3.1 DiscussionA common practice accepted unit ofwater vapor transmission rate is metric g/m2per day.The test1This test method is under the jurisdiction of ASTM Committee F02 on PrimaryBarrier Packaging and is the direct responsibility of Subcommittee F02.10 onPermeation.Current edition approve
14、d Feb.1,2021.Published February 2021.Originallyapproved in 2001.Last previous edition approved in 2016 as D6701 16.DOI:10.1520/D6701-21.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume inform
15、ation,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was develo
16、ped in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1conditions of relative humidity and temperature where thedriving force is the difference in relative humidity across thespecimen must be stated.4.Summary of Test Method4.1 A dry chamber,guard film,and a wet chamber make upa
