ASTM_D_3826_-_98_2013.pdf

Designation:D382698(Reapproved 2013)Standard Practice forDetermining Degradation End Point in DegradablePolyethylene and Polypropylene Using a Tensile Test1This standard is issued under the fixed designation D3826;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.Scope1.1 This practice covers the determination of a degradation-end point(a brittle point)for degradable polyethylene/polypropylene films and sheeting less than 1.0 mm(0.04 in.)thick.This practice is not intended for determination of the rateof degree of degradation of a polyethylene/polypropylene filmor sheet,but rather,to assess when in the course of itsdegradation under some condition,a brittle point is reached.Ifone wishes to monitor tensile elongation during the degrada-tion process(such as when the tensile elongation is signifi-cantly greater than 5%),Test Method D882 is recommended.This practice should not be considered the only way ofdetermining a degradation-end point.1.2 Tensile properties of plastics 1.0 mm(0.04 in.)orgreater in thickness shall be determined in accordance withTest Method D638.1.3 Use a static weighing-constant rate of grip separationtest.This procedure employs a constant rate of separation ofthe grips holding the sample and a static load cell.NOTE1This procedure is based on the use of grip separation as ameasure of extension;however,the desirability of using extensionindicators accurate to 61.0%or better as specified in Test Method D638is recognized,and a provision for the use of such instrumentation isincorporated in the procedure.1.4 This procedure has been successful for determining thedegradation end point of ethylene-carbon-monoxide copoly-mers and has screened successfully two other additive-typepolyethylenes in a round robin test.1.5 The values stated in SI units are to be regarded as thestandard.The values in parentheses are for information only.1.6 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.1.7 There is no equivalent ISO standard.2.Referenced Documents2.1 ASTM Standards:2D374 Test Methods for Thickness of Solid Electrical Insu-lation(Withdrawn 2013)3D618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD882 Test Method for Tensile Properties of Thin PlasticSheetingD5208 Practice for Fluorescent Ultraviolet(UV)Exposureof Photodegradable PlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 Definitions:3.1.1 Definitions of terms and symbols relating to tensiontesting of plastics appear in the Annex to Test Method D638.3.1.2 line grips,nin tensile testing machines,grips havingfaces designed to concentrate the entire gripping force along asingle line perpendicular to the direction of testing stress.3.1.3 tear failure,nin tensile testing of films,a failurecharacterized by fracture initiating at one edge of the specimenand progressing across the specimen at a rate slow enough toproduce an anomalous load-deformation curve.3.2 Definitions of Terms Specific to This Standard:3.2.1 film,nfor the purpose of this practice,a piece ofmaterial not exceeding 0.250 mm(0.01 in.)in thickness.3.2.2 brittlepoint,nindegradablepolyethylene/polypropylene film,that point in the history of a material when75%of the specimens tested have a tensile elongation at breakof 5%or less.1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.96 on Environmentally DegradablePlastics and Biobased Products.Current edition approved Feb.1,2013.Published February 2013.Originallyapproved in 1991.Last previous edition approved in 2008 as D3826 98(2008).DOI:10.1520/D3826-98R13.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Significance and Use4.1 The tensile elongation property determined by thispractice is of value for the characterization of degradablematerials.The tensile elongation property may vary withspecimen thickness,method of preparation,speed of testing,type of grips used,and manner of measuring test extension.Consequently,where precise comparative results are desired,these factors must be carefully controlled.4.2 The