1、Designation: E 2009 08Standard Test Method forOxidation Onset Temperature of Hydrocarbons byDifferential Scanning Calorimetry1This standard is issued under the fixed designation E 2009; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, 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 test method describes the determination of theoxidative properties of hydrocarbons by differential
3、 scanningcalorimetry or pressure differential scanning calorimetry underlinear heating rate conditions and is applicable to hydrocar-bons, which oxidize exothermically in their analyzed form.1.2 Test Method AA differential scanning calorimeter(DSC) is used at ambient pressure, of one atmosphere ofox
4、ygen.1.3 Test Method BApressure DSC (PDSC) is used at highpressure, for example, 3.5 MPa (500 psig) oxygen.1.4 Test Method CA differential scanning calorimeter(DSC) is used at ambient pressure of one atmosphere of air.1.5 The values stated in SI units are to be regarded asstandard. No other units of
5、 measurement are included in thisstandard.1.6 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 regulator
6、y limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 3350 Specification for Polyethylene Plastics Pipe andFittings MaterialsD 3895 Test Method for Oxidative-Induction Time of Poly-olefins by Differential Scanning CalorimetryD 4565 Test Methods for Physical and Environmental Per-fo
7、rmance Properties of Insulations and Jackets for Tele-communications Wire and CableD 5483 Test Method for Oxidation Induction Time of Lu-bricating Greases by Pressure Differential Scanning Calo-rimetryE 473 Terminology Relating to Thermal Analysis and Rhe-ologyE 691 Practice for Conducting an Interl
8、aboratory Study toDetermine the Precision of a Test MethodE 967 Test Method for Temperature Calibration of Differ-ential Scanning Calorimeters and Differential ThermalAnalyzersE 1858 Test Method for Determining Oxidation InductionTime of Hydrocarbons by Differential Scanning Calorim-etry3. Terminolo
9、gy3.1 Definitions:3.1.1 oxidation (extrapolated) onset temperature (OOT)arelative measure of oxidative stability at the cited heating rateis determined from data recorded during a DSC scanningtemperature test. The temperature at which the onset to theobserved oxidation is taken as the OOT.3.1.2 For
10、definitions of terms used in this test method, referto Terminology E 473.4. Summary of Method4.1 The test specimen in an aluminum container and anempty reference aluminum container or pan are heated at aspecified constant heating rate in an oxygen (or air) environ-ment. Heat flow out of the specimen
11、 is monitored as a functionof temperature until the oxidative reaction is manifested byheat evolution on the thermal curve. The oxidation (extrapo-lated) onset temperature (OOT), a relative measure of oxida-tive stability at the cited heating rate, is determined from datarecorded during the scanning
12、 temperature test. The OOTmeasurement is initiated upon reaching the exothermic reactionand measuring the extrapolated onset temperature.4.2 For some particularly stable materials, the OOT may bequite high (300 C) at the specified heating rate of theexperiment. Under these circumstances, the OOT may
13、 bereduced by increasing the pressure of oxygen purge gas.Conversely, reducing the partial pressure of oxygen (such as bythe use of air) may retard reactions that proceed too rapidly,with a corresponding increase of the OOT. By admixing1This test method is under the jurisdiction ofASTM Committee E37
14、 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on ThermalTest Methods and Practices.Current edition approved Sept. 1, 2008. Published October 2008. Originallyapproved in 1999. Last previous edition approved in 2002 as E 200902.2For referenced ASTM standards, visit th
15、e 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
16、United States.oxygen gas with a suitable diluent, for example, nitrogen, theOOT will be increased (see Specification D 3350 and TestMethods D 3895, D 4565, and D 5483).NOTE 1For some systems, the use of copper pans to catalyzeoxidation will reduce the oxidation onset temperature. The results,however
17、, will not necessarily correlate with non-catalyzed tests.5. Significance and Use5.1 Oxidation onset temperature is a relative measure of thedegree of oxidative stability of the material evaluated at a givenheating rate and oxidative environment, for example, oxygen;the higher the OOT value the more
18、 stable the material. TheOOT is described in Fig. 1. The OOT values can be used forcomparative purposes and are not an absolute measurement,like the oxidation induction time (OIT) at a constant tempera-ture (see Test Method E 1858). The presence or effectiveness ofantioxidants may be determined by t
19、his test method.5.2 Typical uses of this test method include the oxidativestability of edible oils and fats (oxidative rancidity), lubricants,greases, and polyolefins.6. Apparatus6.1 Differential Scanning Calorimeter (DSC) or PressureDifferential Scanning Calorimeter (PDSC)The essential in-strumenta
20、tion required to provide the minimum differentialscanning calorimetric capability for this test method includes:a DSC chamber composed of a furnace to provide uniformcontrolled heating of a specimen and a reference to a constantheating rate of at least 10 C/min within the applicabletemperature range
21、 for this test method; a temperature sensor toprovide an indication of the specimen temperature to 6 0.1 C;a differential sensor to detect heat flow (power) differencebetween the specimen and the reference to 0.1 mW; and theinstrument should have the capability of measuring heat flowof at least 6 mW
22、, with provision for less sensitive ranges.NOTE 2In certain cases when the sample under study is of highvolatility (for example, low molecular weight hydrocarbons), the use ofpressures in excess of 0.1 MPa (1 atmosphere) is needed. The operator iscautioned to verify (with apparatus designer) the max
23、imum oxygenpressure at which the apparatus may be safely operated. A PDSC is usedin Method B.6.2 A Data Collection Device, to provide a means ofacquiring, storing, and displaying measured or calculatedsignals, or both. The minimum output signals required for DSCare heat flow, temperature and time.6.
24、3 A high-pressure gas regulator or similar device to adjustthe applied pressure in the test chamber to less than 6 5%,including any temperature dependence on the transducer, isused in Method B.NOTE 3Gas delivery tubing should be kept as short as possible tominimize dead volume. The link between the
25、test chamber and pressuretransducer should allow fast pressure equilibration to ensure accuraterecording of the pressure above the specimen during testing.NOTE 4Caution: Use metal free of organic matter or fluoropolymertubing with oxygen rather than the commonly used rubber or polyvinylchloride plas
26、tic tubing. There have been hazardous situations withprolonged use of certain polymer tubing in oxygen service.6.4 Specimen containers are aluminum sample pans andshould be inert to the specimen and reference material as wellas the oxidizing gas. The specimen containers should be ofsuitable structur
27、al shape and integrity to contain the specimenand reference in accordance with the specific requirements ofthis test method, including a pressure system consisting of apressure vessel or similar means of sealing the test chamber atany applied pressure within the pressure limits required for thistest
28、 method. The specimen containers shall be clean, dry, andflat. A typical cylindrical specimen container has the followingdimensions: height, 1.5 to 2.5 mm and outer diameter, 5.0 to7.0 mm.6.5 Flow meter capable of reading 50 mL/min, or anotherselected flow rate, accurate to within 65 %. Ensure thefl
29、owmeter is calibrated for oxygen. Contact a supplier of flowmeters for specific details on calibration (see Note 4).6.6 Use an analytical balance with a capacity of at least 100mg and capable of weighing to the nearest 0.01 mg, or less than1 % of the specimen or containers masses, or both. Recom-men
30、ded procedure for new sample pan cleaning can be foundin Annex A1.7. Reagents and Materials7.1 Oxygen, extra dry, of not less than 99.5 % by volume, or,NOTE 5Warning: Oxidizer. Gas under pressure.7.2 Air, extra dry.7.3 Indium, of not less than 99.9 % by mass.7.4 Tin, of not less than 99.9 % by mass.
31、8. Sampling8.1 If the sample is a liquid or powder, mix thoroughly priorto sampling.8.2 In the absence of information, samples are to beanalyzed as received. If some heat or mechanical treatment isapplied to the sample prior to analysis, this treatment shall bein nitrogen and noted in the report. If
32、 some heat treatment isused prior to oxidative testing, then record any mass loss as aresult of the treatment.9. Precautions9.1 Caution: Oxygen is a strong oxidizer and vigorouslyaccelerates combustion. Keep surfaces clean.9.2 If the specimen is heated to decomposition, toxic orcorrosive products ma
33、y be released.9.3 For certain types of PDSC, it is recommended that theflow be set up with a reverse flow implementation to ensurethere is no contact of decomposed hydrocarbons with incomingoxygen within the instrument. See instrument designers rec-ommendation on reverse flow.9.4 Certain synthetic l
34、ubricants showed explosion-like onsetof oxidation. Aluminum containers were melted. Care must betaken to avoid damage to the sensor and cell.10. Calibration and Standardization10.1 Calibrate the temperature output of the instrumentusing Practice E 967, using a heating rate of 10 C/min. Useindium and
35、 tin calibration material to bracket typical OOTsdetermined in this test method. Calibration shall be performedunder ambient pressure conditions.E2009082FIG. 1 DSC Oxidation Onset Temperature (OOT), Extrapolated Onset TemperatureE200908311. Procedure11.1 Weigh 3.00 to 3.30 mg of sample, to a precisi
36、on of 60.01 mg, into a clean specimen container. Do not place lid onspecimen pan or container.NOTE 6Other specimen sizes may be used if used consistently.However, the OOT values obtained may differ from those obtained with a3 mg sample. Also, vented specimen covers may be used, but OOT valuesmay dif
37、fer from those obtained in open containers. The followingprocedure assumes the use of open containers.11.2 Place the uncovered container with the prepared speci-men in the sample position of the instrument and an emptyspecimen container, without lid, in the reference position. Besure that the contai
38、ners are centered on the sensors.11.3 Replace all covers in accordance with appropriatemanufactures recommendations.11.4 Adjust flow rate of oxygen gas at ambient pressure to50.0 (65) mL/min, accurate to 6 5%.NOTE 7Other flow rates may be used, but shall be noted in the report.Many flowmeters are no
39、t rated for high pressure operation and may burstif excess pressure is applied. In these cases, the flow rate should bemeasured at atmospheric pressure (0.1 MPa) at the exit of the DSC cell,if recommended by the instrument designer.11.5 Set the instrument sensitivity as required to retain theoxidati
40、on exotherm within the recorded range. A preanalysismay be required to determine this value.Asensitivity of 2 W/g,or less than 6 mW full scale, is typically acceptable.11.6 Purge the specimen area for 3 to 5 min to ensureexchange of air with oxygen at atmospheric pressure. Checkthe flow rate at elev
41、ated pressure, and readjust to 5065mL/min, if required.11.7 Commence programmed heating at 10 C/min fromambient temperature to the onset of the exothermic heat flow.Record the heat flow and sample temperature. The OOT ismeasured in oxygen from the baseline to the extrapolated onsettemperature of the
42、 exothermic process.11.8 Test Methods:11.8.1 When using DSC Test Method A, maintain a flowrate of 50 mL/min-1of oxygen at ambient pressure.11.8.2 When using PDSC Test Method B, pressurize slowly,adjust and maintain pressure of oxygen at 3.5 MPa (500 psig)60.2 MPa (25 psig), and maintain flow rate of
43、 50 mL min-1.11.8.3 When using DSC Test Method C, maintain a flowrate of 50 mL min-1of air at ambient pressure.11.9 Continue the scanning DSC operation until the peak ofthe oxidation exotherm is observed or until an inflection pointis observed and the total displacement from the initial baselineexce
44、eds 3 mW or 1 W/g.11.10 When the experiment is completed, cool the instru-ment to ambient temperature, 25 C.NOTE 8When using Test Method B, allow the instrument to coolbefore releasing the pressure. Failure to do so may result in injury to theuser or damage to the instrument.11.11 OOT values less th
45、an 50 C are not precise. OOTvalues greater than 300 C can be expedited through the use ofa higher oxygen pressure.12. Calculation12.1 Determine the OOT, see Fig. 1.12.1.1 Extend the recorded temperature baseline beyond theoxidation reaction exotherm.12.1.2 Extrapolate the slope of the oxidation exot
46、herm fromthe inflection point on the curve to the extended baseline.12.1.3 Determine the temperature at the intersection of12.1.1 and 12.1.2.12.1.4 The temperature at the intersection is the OOT.13. Report13.1 The report shall include the following:13.1.1 Description and identification of the sample
47、, includ-ing any preparative treatment.13.1.2 Method used: A (DSC in oxygen), B (PDSC inoxygen), or C (DSC in air).13.1.3 Description of the apparatus, including commercialinstrument make and model, if applicable, and specimencontainer.13.1.4 Purge gas chemical composition and pressure.13.1.5 Purge
48、gas flow rate, mL/min.13.1.6 OOT, (61 C) C.13.1.7 Specimen mass, mg.13.1.8 Any modifications or changes to listed conditions.13.1.9 The specific dated version of this method used.14. Precision and Bias14.1 An interlaboratory test, using Method A, was con-ducted in 2001 involving participation by sev
49、en (7) laborato-ries using two (2) instrument models from one (1) manufac-turer. Each laboratory characterized in hextuplicate acommercially available polyethylene Oxidation InductionTime (OIT) reference material3,4. The results were evaluatedusing Practice E 691. The results of this interlaboratory test areon file at ASTM Headquarters.514.2 An interlaboratory test, using Method C, was con-ducted in 2001 involving participation by nine (9) laboratoriesusing four (4) instrument models from one (1) manufacturer.Each laboratory characterized in hextuplicate a c
