ASTM_D_5943_-_96.pdf

Designation:D 5943 96Standard Test Method forDetermining Flexural Properties of Plastics1This standard is issued under the fixed designation D 5943;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method specifies a procedure for determiningthe flexural properties of plastics under defined conditions.Astandard test specimen is defined,but parameters are includedfor alternative specimen sizes for use where appropriate.Arange of testing speeds is included.1.2 The procedure is used for investigating the flexuralbehavior of the test specimens and for determining the flexuralstrength,flexural modulus,and other aspects of the flexuralstress/strain relationship under the conditions defined.It ap-plies to a freely supported beam,loaded at midspan(three-point loading test).1.3 The procedure is suitable for use with the followingrange of materials:1.3.1 Thermoplastics molding and extrusion materials,in-cluding filled and reinforced compounds in addition to unfilledtypes;rigid thermoplastics sheets;1.3.2 Thermosetting molding materials,including filled andreinforced compounds;thermosetting sheets,including lami-nates;and1.3.3 Thermotropic liquid-crystal polymers.1.4 The procedure is not normally suitable for use with rigidcellular materials and sandwich structures containing cellularmaterial.NOTE1For certain types of textile-fiber-reinforced plastics,a four-point bending test is preferred.This is currently under consideration inISO.1.5 The procedure is performed using specimens that maybe either molded to the chosen dimensions,machined from thecentral portion of a standard multipurpose test specimen(seeISO 3167(Specification D 5936),or machined from finishedand semi-finished products such as moldings,laminates,andextruded or cast sheet.1.6 The procedure specifies preferred dimensions for thetest specimen.Tests that are conducted on specimens ofdifferent dimensions,or on specimens that are prepared underdifferent conditions,may produce results that are not compa-rable.Other factors,such as the speed of testing and condi-tioning of the specimens,can also influence the results.Consequently,when comparative data are required,thesefactors must be controlled and recorded carefully.1.7 Flexural properties can be used for engineering designpurposes only for materials with linear stress/strain behavior.For non-linear material behavior the flexural properties areonly nominal.The bending test should be used preferentiallywith brittle materials,for which tensile tests are difficult.1.8 This test method is identical to ISO 178.This testmethod is comparable to Test Methods D 790,but neither testmethod should be substituted for the other.The two testmethods may differ with respect to test specimen dimensions,test specimen conditioning,test equipment,testing conditions,etc.The two test methods may not give the same results.1.9 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.10 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:D 790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-als2D 5936 Specification for Multipurpose Test SpecimensUsed for Testing Plastics3D 5939 Practice for Preparing Multipurpose Test Specimensand Bars of Thermoplastics by Injection Moulding3D 5940 Practice for Preparing Small Plate Test Specimensof Thermoplastics by Injection Moulding32.2ISO Standards:4ISO 178 Determination of Flexural PropertiesISO 291:1977 PlasticsStandard Atmospheres for Condi-tioning and TestingISO 293:1986 PlasticsCompression Moulding Test Speci-mens of Thermoplastic MaterialsISO 294 PlasticsInjection Moulding of Test Specimens ofThermoplastic MaterialsISO 295:1991 PlasticsCompression Moulding of Test1Bias This test method is under the jurisdiction of ASTM Committee D-20 onPlastics and is the direct responsibility of Subcommittee D20.61 on USA TechnicalAdvisory Group for ISO/TC 61 on Plastics.Current edition approved June 10,1996.Published August 1996.2Annual Book of ASTM Standards,Vol 08.01.3Annual Book of ASTM Standards,Vol 08.03.4Available from American National Standards Institute,11 W.42nd St.,13thFloor,New York,NY 10036.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMNOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM In