ASTM_D_6395_-_11.pdf

Designation:D639511Standard Test Method forFlatwise Flexural Impact Resistance of Rigid Plastics1This standard is issued under the fixed designation D6395;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 The resistance of plastics to breakage by flexural shockmay be determined by test methods such as those contained inTest Method D256.Specimens used in those test methodsfeature a milled notch to promote brittle fracture.The testspecimens are struck by a pendulum with the depth dimensionparallel to the direction of pendulum swing.This test method isdifferentiated from the others by its application to the assess-ment of the affect on impact resistance of changes in thesurface of specimens resulting from weathering or otherexposure.In this test method,specimens are struck by apendulum with the depth dimension perpendicular to thedirection of pendulum swing.Test Method D5420 may also beused to conduct testing of weathered or exposed specimens.This test method is differentiated from Gardner Impact by thesmaller size of the specimens,which may result in substantiallyhigher productivity of accelerated weathering instruments.Additionally,this test method provides multiple data from asingle specimen for characterization of within specimen vari-ability.1.2 This test method describes the determination of theresistance of rigid plastic strip specimens to breakage orpermanent deformation when one end of the specimen issubjected to an impact upon its wide face while the other endof the specimen is firmly clamped.1.3 This test method is applicable to specimens of 1.60 mm(0.0625 in.)thickness.However,the limits of applicability ofthe test are not sharply defined,and specimens having otherdimensions may frequently be used.For specimens of thick-nesses other than 1.60 mm(0.0625 in.)the ratio of the distancebetween the top of the clamp and the centerline of the roundedstriking edge to the specimen thickness must be 2.5 6 0.1.1.4 This test method measures the relative impact resistanceof samples having approximately the same thickness.Normal-ization of the impact resistance to unit cross-sectional area onlypartly compensates for the effects of specimen thicknessvariation because,at the fixed cantilever length,the ratio ofshear stress to tensile stress in bending increases withthickness,and the importance of these effects in contributing tothe energy absorbed is greater for ductile than for brittle failure.1.5 This test method is used primarily as a means ofassessing,for a series of samples,changes relative to a controldue to some treatment such as weathering or exposure to activeenvironments.It has been particularly useful as a sensitiveindicator of the development of surface cracks or a brittlesurface.The existence or formation of cracks in an inherentlybrittle surface produces marked lowering of impact strengthwhen that surface is the one subjected to tension in the test.1.6 This test method is not generally applicable to materialssuch as elastomers or nonrigid plastics in which there is nofracture,permanent deformation,or other change due toyielding in flexure.However,it may be desirable to test suchmaterials as file samples to establish reference points when thetest is applied as described in 1.5.1.7 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.8 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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D256 Test Methods for Determining the Izod PendulumImpact Resistance of PlasticsD618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD5420 Test Method for Impact Resistance of Flat,RigidPlastic Specimen by Means of a Striker Impacted by aFalling Weight(Gardner Impact)D5947 Test Methods for Physical Dimensions of SolidPlastics Specimens1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.Current edition approved April 1,2011.Published April 2011.Originallyapproved in 1999.Last previous edition approved in 2010 as D6395-10.DOI:10.1520/D6395-11.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM