1、Designation:D389514Standard Test Method forOxidative-Induction Time of Polyolefins by DifferentialScanning Calorimetry1This standard is issued under the fixed designation D3895;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year
2、 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.Scope*1.1 This test method outlines a procedure for the determi-nation of oxidative-induction time(OIT)of polymeric materi-als b
3、y differential scanning calorimetry(DSC).It is applicableto polyolefin resins that are in a fully stabilized/compoundedform.1.2 The values stated in SI units are to be regarded as thestandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is
4、 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.Specific hazardsinformation is given in Section 8.NOTE1This standard and ISO 113576 2013 address the same subjectmatter,but di
5、ffer in technical content.2.Referenced Documents2.1 ASTM Standards:2D4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens,Plaques,or SheetsE473 Terminology Relating to Thermal Analysis and Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Prec
6、ision of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzers3.Terminology3.1 DefinitionsDefinitions of terms applying to thermalanalysis appear in Terminology E473.3.2 Definitions of Terms Specific to This Standard:3.2.
7、1 oxidative induction timea relative measure of amaterials resistance to oxidative decomposition;it is deter-mined by the thermoanalytical measurement of the timeinterval to onset of exothermic oxidation of a material at aspecified temperature in an oxygen atmosphere.3.2.2 Abbreviations:3.2.3 HDPEhi
8、gh-density polyethylene.3.2.4 LDPElow-density polyethylene.3.2.5 LLDPElinear low-density polyethylene.3.2.6 OIToxidative induction time.4.Summary of Test Method4.1 The sample to be tested and the reference material areheated at a constant rate in an inert gaseous environment(nitrogen).When the speci
9、fied temperature has been reached,the atmosphere is changed to oxygen maintained at the sameflow rate.The specimen is then held at constant temperatureuntil the oxidative reaction is displayed on the thermal curve.The OIT is determined from the data recorded during theisothermal period.The time inte
10、rval from when the oxygenflow is first initiated to the oxidative reaction is referred to asthe induction period.4.1.1 The end of the induction period is signaled by anabrupt increase in the specimens evolved heat or temperatureand will be recorded as an exothermic event by a differentialscanning ca
11、lorimeter(DSC).4.2 The type of containment system used depends on theintended application use of the material being tested.Polyole-fins used in the wire and cable industry typically require copperor aluminum pans,whereas polyolefins used in geomembraneand vapor-barrier film applications exclusively
12、use aluminumpans.4.3 Unless otherwise specified,the analysis temperatureused in this test has been set arbitrarily at 200.0C.For samplesthat have relatively low or high stabilization levels,it ispossible to adjust the temperature(typically between 180 and220C)to yield a thermal curve that can be int
13、erpreted andanalyzed easily.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.30 on Thermal Properties.Current edition approved Dec.1,2014.Published January 2015.Originallyapproved in 1980.Last previous edition approved
14、in 2007 as D3895 07.DOI:10.1520/D3895-14.2For 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.*A Summary of Changes sec
15、tion appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.Significance and Use5.1 The OIT is a qualitative assessment of the level(ordegree)of stabilization of the material tested.This test has thepotential
16、 to be used as a quality control measure to monitor thestabilization level in formulated resin as received from asupplier,prior to extrusion.NOTE2The OIT measurement is an accelerated thermal-aging testand as such can be misleading.Caution should be exercised in datainterpretation since oxidation reaction kinetics are a function of tempera-ture and the inherent properties of the additives contained in the sample.For example,OIT results are often used to select optimum resinformulations.Volatile
