ASTM_E_1877_-_15.pdf

Designation:E187715Standard Practice forCalculating Thermal Endurance of Materials fromThermogravimetric Decomposition Data1This standard is issued under the fixed designation E1877;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 describes the determination of thermalendurance,thermal index,and relative thermal index fororganic materials using the Arrhenius activation energy gener-ated by thermogravimetry.1.2 This practice is generally applicable to materials with awell-defined thermal decomposition profile,namely a smooth,continuous mass change.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 There is no ISO standard equivalent to this practice.1.5 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:2E1641 Test Method for Decomposition Kinetics by Thermo-gravimetry Using the Ozawa/Flynn/Wall MethodE2550 Test Method for Thermal Stability by Thermogravi-metryE2958 Test Methods for Kinetic Parameters by Factor Jump/Modulated Thermogravimetry3.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 failure,nchange in some chemical,physical,mechanical,electrical or other property of sufficient magnitudeto make it unsuitable for a particular use.3.1.2 failure temperature(Tf),nthe temperature at which amaterial fails after a selected time.3.1.3 thermal index(TI),nthe temperature correspondingto a selected time-to-failure.3.1.4 relative thermal index(RTI),nthe temperature cor-responding to a selected time-to-failure when compared withthat of a control with proven thermal endurance characteristics.3.1.4.1 DiscussionThe TI and RTI are considered to be themaximum temperature below which the material resistschanges in its properties over a selected period of time.In theabsence of comparison data for a control material,a thermalendurance(time-to-failure)of 60 000 h has been arbitrarilyselected for measuring TI and RTI.3.1.5 thermal endurance,nthe time-to-failure correspond-ing to a selected temperature.Also known as thermal lifetimeor time-to-failure.4.Summary of Practice4.1 The Arrhenius activation energy obtained from otherTest Methods(such as Test Methods E1641 and E2958,etc.)isused to construct the thermal endurance curve of an organicmaterial from which an estimate of lifetime at selected tem-peratures may be obtained.5.Significance and Use5.1 Thermogravimetry provides a rapid method for thedetermination of the temperature-decomposition profile of amaterial.5.2 This practice is useful for quality control,specificationacceptance,and research.5.3 This test method is intended to provide an acceleratedthermal endurance estimation in a fraction of the time requirefor oven-aging tests.The primary product of this test method isthe thermal index(temperature)for a selected estimatedthermal endurance(time)as derived from material decompo-sition.5.4 Alternatively,the estimated thermal endurance(time)ofa material may be estimated from a selected thermal index(temperature).5.5 Additionally,the estimated thermal endurance of amaterial at selected failure time and temperature may be1This practice is under the jurisdiction of Committee E37 on Thermal Measure-ments and is the direct responsibility of Subcommittee E37.10 on Fundamental,Statistical and Mechanical Properties.Current edition approved March 1,2015.Published March 2015.Originallyapproved in 1997.Last previous edition approved in 2013 as E1877 13.DOI:10.1520/E1877-15.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 estimated when compared to a reference value for thermalendurance and thermal index obtained from electrical ormechanical oven aging tests.5.6 This practice shall not be used for product lifetimepredications unless a correlation between test results and actuallifetime has been demonstrated.In many cases,multiplemechanisms occur during the decomposition of a material,with one mechanism dominating over one temperature range,and a different mechanism dominating in a different tempera-ture range.Users of this practice are cautioned to demonstratefor their system that any temperature extrapolations are tech-nically sound.6.Calculation6.1 The following values ar