1、Designation:D74614Standard Test Method forBrittleness Temperature of Plastics and Elastomers byImpact1This standard is issued under the fixed designation D746;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.
2、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 te
3、m-perature at which plastics and elastomers(as defined byTerminology D883)exhibit brittle failure under specifiedimpact conditions.Two routine inspection and acceptanceprocedures are also provided.NOTE1When testing rubbers for impact brittleness use Test MethodD2137.When testing plastic sheeting for
4、 impact brittleness,use TestMethod D1790.1.2 The values stated in SI units are to be regarded as thestandard.1.3 Due to the potential safety and environmental hazardsassociated with mercury-filled thermometers,the use of alter-native temperature measuring devices(such as thermocouplesand RTDs)is enc
5、ouraged.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 and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE2This
6、test method and ISO 974 address the same subjectmatter,but differ in technical content.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD832 Practice for Rubber Conditioning For Low Tempera-ture TestingD883 Terminology Relating to PlasticsD1790 Test Method
7、 for Brittleness Temperature of PlasticSheeting by ImpactD2137 Test Methods for Rubber PropertyBrittleness Pointof Flexible Polymers and Coated FabricsE1 Specification for ASTM Liquid-in-Glass ThermometersE77 Test Method for Inspection and Verification of Ther-mometersE608/E608M Specification for Mi
8、neral-Insulated,Metal-Sheathed Base Metal ThermocouplesE1137/E1137M Specification for Industrial Platinum Resis-tance Thermometers2.2 ISO Standard:ISO 974 PlasticsDetermination of the Brittleness Tem-perature by Impact32.3 ASTM Adjuncts:Detailed Drawing of a Typical Clamp43.Terminology3.1 GeneralThe
9、 definitions of plastics used in this testmethod are in accordance with Test Method D883 unlessotherwise specified.3.2 brittleness temperaturethat temperature,estimatedstatistically,at which 50%of the specimens would probablyfail.3.3 failed specimenthe division of a specimen into two ormore complete
10、ly separated pieces or as any crack in thespecimen which is visible to the unaided eye.4.Summary of Test Method4.1 To determine the brittleness temperature,specimens aresecured to a specimen holder using a torque wrench.Thespecimen holder is immersed in a bath containing a heat-transfer medium,which
11、 has been cooled.The specimens arestruck at a specified linear speed and then examined forfailures.The brittleness temperature is defined as the tempera-ture at which 50%of the specimens would probably fail.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direc
12、t responsibility of Subcommittee D20.30 on Thermal Proper-ties.30.07).Current edition approved Dec.1,2014.Published December 2014.Originallyapproved in 1943.Last previous edition approved in 2013 as D746 13.DOI:10.1520/D0746-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcon
13、tact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3ISO Standards Handbook 21,Vol 1.ISO Standards are available fromAmericanNational Standards Institute(ANSI),25 W.43rd St.,4th Floor,New Yo
14、rk,NY10036.4A detailed drawing of a typical clamp may be obtained from ASTM Headquar-ters.Order Adjunct:ADJD0746.*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 States1 5.Significan
15、ce and Use5.1 This test method establishes the temperature at which50%of the specimens tested would probably fail whensubjected to the conditions specified herein.The test providesfor the evaluation of long-time effects such as crystallization,or those effects that are introduced by low-temperature
16、incom-patibility of plasticizers in the material under test.Plastics andelastomers are used in many applications requiring low-temperature flexing with or without impact.Use data obtainedby this method to predict the behavior of plastic and elasto-meric materials at low temperatures only in applications inwhich the conditions of deformation are similar to thosespecified in this test method.This test method has been founduseful for specification purposes,but does not necessarilymeasure the lowest
