ASTM_D_3850_-_12.pdf

Designation:D385012Standard Test Method forRapid Thermal Degradation of Solid Electrical InsulatingMaterials By Thermogravimetric Method(TGA)1This standard is issued under the fixed designation D3850;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 This test method outlines a procedure for obtainingthermogravimetric(TGA)data on solid polymeric materialsintended for use as electrical insulating materials.1.2 Do not use this standard to quantify an estimate of thelong-term thermal capability for any electrical insulating ma-terial.If a relationship exists between TGA and the long-termthermal capabilities of a material,then that fact must beestablished and made public,preferably by comparing databetween a candidate and another material known to displaysimilar failure modes.1.3 The values stated in SI units are the standard.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.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD1600 Terminology forAbbreviated Terms Relating to Plas-ticsD1711 Terminology Relating to Electrical InsulationD2307 Test Method for Thermal Endurance of Film-Insulated Round Magnet WireE220 Test Method for Calibration of Thermocouples ByComparison TechniquesE473 Terminology Relating to Thermal Analysis and Rhe-ologyE1582 Practice for Calibration of Temperature Scale forThermogravimetry3.Terminology3.1 DefinitionsDefinitions are in accordance with Termi-nology D883,Terminology D1711,and Terminology E473.3.2 AbbreviationsAbbreviations are in accordance withTerminology D1600,unless otherwise indicated.4.Summary of Test Method4.1 This thermogravimetric technique uses the record of themass loss versus the temperature of the specimen during thetime of exposure to a specified prescribed environment using acontrolled time rate of heating.4.2 The record is a TGA curve,with percent of initial massas the ordinate and temperature as the abscissa(see Figs.1 and2).4.3 The temperature is measured and recorded at specifiedmass loss points(recorded as a TGAcurve),using an electronicchart recorder or other suitable data acquisition device.5.Significance and Use5.1 Thermogravimetry is useful in determining the dynamicfunctional effect of temperature on the amount of volatilematerials leaving a specimen as the latter is heated progres-sively to higher temperatures.TGA can be useful for processcontrol,process development,material evaluation,and foridentification and quality control in specifications.5.2 The thermal stability of a material can be associatedwith the degree and time rate of mass loss as a function oftemperature.TGA curves can,therefore,be used as a prelimi-nary screen method in the evaluation of relative behavior ofinsulating materials of the same generic family.5.3 The functional temperature-life relationship of an insu-lating material in any given application depends on a numberof service and environmental factors.Therefore,the informa-tion obtained from TGA curves is not adequate by itself todescribe the thermal capability of an insulating material.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.17 on Thermal Characteristics.Current edition approved Jan.1,2012.Published February 2012.Originallyapproved in 1979.Last previous edition approved in 2006 as D3850 94(2006).DOI:10.1520/D3850-12.2For 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 5.4 Refer to the Appendix for further discussion of theinterpretation of TGA data.6.Apparatus6.1 Thermogravimetric AnalyzerA system of related in-struments comprising:6.1.1 Microbalance,of the null type,sensitive to 0.001 mg,6.1.2 Furnace,controllable at a constant rate over a tem-perature range of interest,typically 25 to 1000C,6.1.3 Temperature Programmer,capable of providing alinear rate of rise of the furnace at a predetermined value(normally 5C/min)with a tolerance of 6 0.1C/min,Sample 8.54 mg Heating Rate 5C/min Purging Gas Flow 0.8 mL/sFIG.1 Curve No.1,Typical TGA for Polyester FilmSample 5.93 mg Heating Rate 5C/min Purging Gas Flow 0.8 mL/sFIG.2 Curve No.2,Typica