1、Designation: E 2009 02Standard 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 (e) 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 differentia
3、l 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 Computer or electronic-based instruments, techniques,or data treatment equivalent to this test method ma
4、y also beused.NOTE 1Users of this test method are expressly advised that all suchinstruments or techniques may not be equivalent. It is the responsibility ofthe user of this standard to determine the necessary equivalency prior touse.1.3 Test Method AA differential scanning calorimeter(DSC) is used
5、at ambient pressure, of one atmosphere ofoxygen.1.4 Test Method BA pressure DSC (PDSC) is used at highpressure, for example, 3.5 MPa (500 psig) oxygen.1.5 Test Method CA differential scanning calorimeter(DSC) is used at ambient pressure of one atmosphere of air.1.6 SI units are the standard.1.7 This
6、 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 Documents
7、2.1 ASTM Standards:D 3350 Specification for Polyethylene Plastics Pipe andFittings Materials2D 3895 Test Method for Oxidative-Induction Time of Poly-olefins by Differential Scanning Calorimetry2D 4565 Test Method for Physical Environmental Perfor-mance Properties of Insulations and Jackets for Telec
8、om-munications Wire and Cable3D 5483 Test Method for Oxidation Induction Time of Lu-bricating Greases by Pressure Differential Scanning Calo-rimetry4E 473 Terminology Relating to Thermal Analysis5E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method5E 967
9、Practice for Temperature Calibration of DifferentialScanning Calorimeters and Differential Thermal Analyz-ers5E 1858 Test Method for Determining Oxidative InductionTime of Hydrocarbons by Differential Scanning Calorim-etry53. Terminology3.1 Definitions:3.1.1 oxidation (extrapolated) onset temperatur
10、e (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 definitions of terms used in this test method, referto Terminolog
11、y 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 is monitored as a functionof temperature until the oxidative rea
12、ction 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 temperature test. The OOT1This test method is under the jurisdic
13、tion of ASTM Committee E37 on ThermalMeasurements and is the direct responsibility of Subcommittee E37.01 on TestMethods and Recommended Practices.Current edition approved Dec. 10, 2002. Published February 2003. Originallypublished as E 200999. Last previous edition approved as E 200999.2Annual Book
14、 of ASTM Standards, Vol 08.02.3Annual Book of ASTM Standards, Vol 10.02.4Annual Book of ASTM Standards, Vol 05.03.5Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.measurement is initiated upon
15、 reaching the exothermic reactionand measuring the extrapolated onset temperature.4.2 For some particularly stable materials, the OOT may bequite high (300C) at the specified heating rate of theexperiment. Under these circumstances, the OOT may bereduced by increasing the pressure of oxygen purge ga
16、s.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 admixingoxygen gas with a suitable diluent, for example, nitrogen, theOOT will be increased (see Specification D 3350 and TestMe
17、thods D 3895, D 4565, and D 5483).NOTE 2For some systems, the use of copper pans to catalyzeoxidation will reduce the oxidation onset temperature. The results,however, will not necessarily correlate with non-catalyzed tests.5. Significance and Use5.1 Oxidation onset temperature is a relative measure
18、 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 stable the material. TheOOT is described in Fig. 1. The OOT values can be used forcomparative purposes and are not an absolute measur
19、ement,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 this test method.5.2 Typical uses of this test method include the oxidativestability of edible oils and fats (oxidative rancidity), lub
20、ricants,greases, and polyolefins.6. Apparatus6.1 Differential Scanning Calorimeter (DSC) or PressureDifferential Scanning Calorimeter (PDSC)The essential in-strumentation required to provide the minimum differentialscanning calorimetric capability for this test method includes:a DSC chamber composed
21、 of a furnace to provide uniformcontrolled heating of a specimen and a reference to a constantheating rate of at least 10C/min within the applicable tem-perature range for this test method; a temperature sensor toprovide an indication of the specimen temperature to 6 0.1C;a differential sensor to de
22、tect 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, with provision for less sensitive ranges.NOTE 3In certain cases when the sample under study is of highvolatility (for example, low m
23、olecular weight hydrocarbons), the use ofpressures in excess of 0.1 MPa (1 atmosphere) is needed. The operator iscautioned to verify (with apparatus designer) the maximum oxygenpressure at which the apparatus may be safely operated. A PDSC is usedin Method B.6.2 Recorder or printer/plotter, or simil
24、ar device, is used,capable of displaying heat flow on the Y-axis and temperatureon the X-axis. The temperature shall be accurate to 60.3C(see Practice E 967) and be readable to 0.1C. The capability torecord the first derivative of the heat flow curve is helpful incases in which the baseline is not c
25、onstant.6.3 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 4Gas delivery tubing should be kept as short as possible tominimize dead volume. The link be
26、tween the test chamber and pressuretransducer should allow fast pressure equilibration to ensure accuraterecording of the pressure above the specimen during testing.NOTE 5Caution: Use metal or fluoropolymer tubing with oxygenrather than the commonly used rubber or polyvinyl chloride plastic tubing.T
27、here have been hazardous situations with prolonged use of certainpolymer 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 structural shape and
28、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 method. The
29、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 theflowmeter is ca
30、librated for oxygen. Contact a supplier of flowmeters for specific details on calibration (see Note 5).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-mended procedure
31、 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 6Warning: 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.8. Sampling8.
32、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 some heat tr
33、eatment 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 may be released
34、.9.3 For certain types of PDSC, it is recommended that theflow be set up with a reverse flow implementation to ensureE2009022FIG.1DSCOxidationOnsetTemperature(OOT),ExtrapolatedOnsetTemperatureE2009023there is no contact of decomposed hydrocarbons with incomingoxygen within the instrument. See instru
35、ment designers rec-ommendation on reverse flow.9.4 Certain synthetic lubricants showed explosion-like onsetof oxidation. Aluminum containers were melted. Care must betaken to avoid damge to the sensor and cell.10. Calibration and Standardization10.1 Calibrate the temperature output of the instrument
36、using Practice E 967, using a heating rate of 10C/min. Useindium and tin calibration material to bracket typical OOTsdetermined in this test method. Calibration shall be performedunder ambient pressure conditions.11. Procedure11.1 Weigh 3.00 to 3.30 mg of sample, to a precision of 60.01 mg, into a c
37、lean specimen container. Do not place lid onspecimen pan or container.NOTE 7Other 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 differ from those obtained
38、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 containers are centered on the
39、 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 8Other flow rates may be used, but shall be noted in the report.Many flowmeters are not rated for high pressur
40、e 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 theoxidation exotherm within the r
41、ecorded range. A preanalysismay be required to determine this value. A sensitivity 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 elevated pressure, and rea
42、djust to 5065mL/min, if required.11.7 Commence programmed heating at 10C/min fromambient temperature to the onset of the exothermic heat flow.Record theheat flow and sample temperature. The OOT ismeasured in oxygen from the baseline to the extrapolated onsettemperature of the exothermic process.11.8
43、 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 50 mL min-1.11.8.3 When
44、 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 baselineexceeds 3 mW or 1 W/g.11.10
45、When the experiment is completed, cool the instru-ment to ambient temperature, 25C.NOTE 9When 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 than 50C are not precise. O
46、OTvalues greater than 300C 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 exotherm fromthe inflection poi
47、nt 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, includ-ing any preparativ
48、e 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 gas flow rate, mL/min.13.1.
49、6 OOT, (61C) 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 seven (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 material6,7. The results were evaluatedusing Practice E 691. The results of this interl
