1、Designation:D304592(Reapproved 2010)Standard Practice forHeat Aging of Plastics Without Load1This standard is issued under the fixed designation D3045;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number
2、 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.Scope1.1 This practice is intended to define the exposure condi-tions
3、 for testing the resistance of plastics to oxidation or otherdegradation when exposed solely to hot air for extendedperiods of time.Only the procedure for heat exposure isspecified,not the test method or specimen.The effect of heaton any particular property may be determined by selection ofthe appro
4、priate test method and specimen.1.2 This practice should be used as a guide to comparethermal aging characteristics of materials as measured by thechange in some property of interest.This practice recommendsprocedures for comparing the thermal aging characteristics ofmaterials at a single temperatur
5、e.Recommended proceduresfor determining the thermal aging characteristics of a materialat a series of temperatures for the purpose of estimating time toa defined property change at some lower temperature are alsodescribed.1.3 This practice does not predict thermal aging character-istics where intera
6、ctions between stress,environment,temperature,and time control failure occurs.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 determin
7、e the applica-bility of regulatory limitations prior to use.NOTE1ISO-2578 is considered to be technically equivalent to thispractice.2.Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsD1870 Practice for Elevated Temperatu
8、re Aging Using aTubular Oven(Withdrawn 1998)3D1898 Practice for Sampling of Plastics(Withdrawn 1998)3E145 Specification for Gravity-Convection and Forced-Ventilation OvensE456 Terminology Relating to Quality and Statistics2.2 ISO Standard:ISO 2578(1974)Determination of Time-Temperature Lim-its After
9、 Exposure to Prolonged Action of Heat43.Terminology3.1 The terminology given in Terminology D883 and Ter-minology E456 is applicable to this practice.4.Significance and Use4.1 The use of this practice presupposes that the failurecriteria selected to evaluate materials(that is,the property orproperti
10、es being measured as a function of exposure time)andthe duration of the exposure can be shown to relate to theintended use of the materials.4.2 Plastic materials exposed to heat may be subject tomany types of physical and chemical changes.The severity ofthe exposures in both time and temperature det
11、ermines theextent and type of change that takes place.A plastic material isnot necessarily degraded by exposure to elevated temperatures,but may be unchanged or improved.However,extendedperiods of exposure of plastics to elevated temperatures willgenerally cause some degradation,with progressive cha
12、nge inphysical properties.4.3 Generally,short exposures at elevated temperatures maydrive out volatiles such as moisture,solvents,or plasticizers,relieve molding stresses,advance the cure of thermosets,andmay cause some change in color of the plastic or coloringagent,or both.Normally,additional shri
13、nkage should beexpected with loss of volatiles or advance in polymerization.4.4 Some plastic materials may become brittle due to loss ofplasticizers after exposure at elevated temperatures.Other1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility
14、of Subcommittee D20.50 on Durability of Plastics.Current edition approved March 15,2010.Published June 2010.Originallyapproved in 1974.Last previous edition approved in 2003 as D3045 92(2003).DOI:10.1520/D3045-92R10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Cu
15、stomer 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.4Available from American National Standards Institute(ANSI),25 W.4
16、3rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 types of plastics may become soft and sticky,either due tosorption of volatilized plasticizer or due to breakdown of thepolymer.4.5 The degree of change observed will depend on theproperty measured.Different properties,mechanical orelectrical,may not change at the same rate.For instance,thearc resistance of thermosetting compounds im