ASTM D5885D5885M-17 Standard Test Method for Oxidative Induction Time of Polyolefin Geosynthetics by High-Pressure Differential Scanning Calorimetry.pdf

1、Designation: D5885/D5885M 17Standard Test Method forOxidative Induction Time of Polyolefin Geosynthetics byHigh-Pressure Differential Scanning Calorimetry1This standard is issued under the fixed designation D5885/D5885M; the number immediately following the designation indicates theyear of original

2、adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers a procedure for the determina-tion of the ox

3、idative induction time (OIT) of polyolefingeosynthetics using high-pressure differential scanning calo-rimetry.1.2 The focus of the test is on geomembranes, but geogrids,geonets, geotextiles, and other polyolefin-related geosyntheticsare also suitable for such evaluation.1.3 This test method measure

4、s the oxidative induction timeassociated with a given test specimen at a specified temperatureand pressure.1.4 This is an accelerated test for highly stabilized materials.It is applicable only to material whose OIT values under3.4 MPa of oxygen is greater than 30 min at 150 C.1.5 The values stated i

5、n either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.6 This s

6、tandard 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. Specific precau-tionary

7、statements are given in Section 8.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade

8、 Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D3895 Test Method for Oxidative-Induction Time of Poly-olefins by Differential Scanning CalorimetryD4439 Terminology for GeosyntheticsD4491/D4491M Test Methods for Water Permeability ofGeotextiles by

9、PermittivityD4565 Test Methods for Physical and Environmental Per-formance Properties of Insulations and Jackets for Tele-communications Wire and CableD4703 Practice for Compression Molding ThermoplasticMaterials into Test Specimens, Plaques, or SheetsE473 Terminology Relating to Thermal Analysis an

10、d Rhe-ologyE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersG88 Guide for Designing Systems for Oxygen Service3. Terminology3.1 Defini

11、tions:3.1.1 For definitions of terms related to geosynthetics, referto Terminology D4439.3.1.2 Definitions of terms applying to thermal analysisappear in Terminology E473.3.2 Definitions of Terms Specific to This Standard:3.2.1 differential scanning calorimetry (DSC), na tech-nique in which the diff

12、erence in heat flow inputs into asubstance and a reference material is measured as a function oftemperature or time, while the substance and reference materialare subjected to a controlled-temperature program. (See Ter-minology E473.)3.2.2 geomembrane, nan essentially impermeable geosyn-thetic compo

13、sed of one or more synthetic sheets. (See Termi-nology D4439.)1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.02 on Endur-ance Properties.Current edition approved June 1, 2017. Published June 2017. Originallyappro

14、ved in 1995. Last previous edition approved in 2015 as D5885/D5885M 15.DOI: 10.1520/D5885_D5885M-17.2For 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 Do

15、cument Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on

16、 Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.13.2.2.1 DiscussionIn this test method, essentially imper-meable means that no measurable liquid flows through ageosynthetic when t

17、ested in accordance with Test MethodsD4491/D4491M.3.2.3 geosynthetic, na planar product manufactured frompolymeric material used with soil, rock, earth, or other geo-technical engineering-related material as an integral part of aman-made project, structure, or system. (See TerminologyD4439.)3.2.4 hi

18、gh-pressure differential scanning calorimetry(HPDSC), ndifferential scanning calorimetry in which thesubstance and reference material are exposed to a controlledsuperambient atmosphere.3.2.5 index test, na test procedure that may be used toestablish an order for a set of specimens with respect to th

19、eproperty of interest.3.2.6 oxidative induction time (OIT), nthe elapsed timebetween first exposure to an oxidizing gas and the onset tooxidation of a material under isothermal conditions.3.2.6.1 DiscussionOxidative induction time is an indextest parameter dependent upon a wide range of experimental

20、conditions including temperature, pressure of oxygen, purgegas flow rate, and the presence or absence of catalysts.4. Summary of Test Method4.1 The specimen to be tested is heated from room tempera-ture at a constant rate in a non-purging, high-pressure oxygenenvironment at a defined pressure. When

21、the specified tem-perature has been reached, the specimen is then held at thattemperature until the oxidative reaction is displayed on thethermal curve. The OIT is the time interval from the start of thetemperature program test to the onset of the oxidative reaction.4.2 In this procedure, an elevate

22、d pressure of oxygen is usedto accelerate the reaction and to reduce analysis time.4.3 Unless otherwise specified, the temperature used in thistest method shall be 150 C, and the chamber pressure is to bemaintained at 3.4 MPa 500 psi using a constant volume testcondition.5. Significance and Use5.1 T

23、he oxidative induction time is a characteristic of acompounded polyolefin product that is dependent not only onthe type and amount of additives present, but also on the typeof resin. In well-behaved systems, this test method can be usedas a quality control measure to monitor the stabilization ingeos

24、ynthetics as received from a supplier.5.2 When this test method is used to compare differentgeomembrane formulations containing different antioxidantpackages, then those results shall be considered valid only atthe temperature of test.5.3 This test method is intended as a geosynthetic test. Useof th

25、e OIT value to estimate the lifetime of the geomembranefrom which the test specimen is taken is not addressed, norshall it be used for this purpose.5.3.1 The OIT measurement is an accelerated thermal agingtest and, as such, interpretation of resulting data may bemisleading if done by an inexperience

26、d operator. Cautionshould be exercised in data interpretation since oxidationreaction kinetics are a function of temperature and the proper-ties of the additives contained in the geosynthetic sample. Forexample, OIT values are often used to select optimum resinformulations. Certain antioxidants, how

27、ever, may generatepoor OIT results even though they may be adequate at theirintended use temperature and vice versa.5.4 This test method can be used for other purposes such asmanufacturing control and research and development.5.5 Oxidation induction time is strongly dependent upontest temperature an

28、d the partial pressure of oxygen. The higherthe test temperature or the oxygen partial pressure, or both, theshorter the oxidation induction time.5.5.1 The use of high test temperature, however, may havedeleterious effects. The first of these is the potential volatiliza-tion of additive packages use

29、d to stabilize the test materials.The second is the potential for the influence of chemicalmechanisms which are not significant at end-use operationconditions.5.5.2 This test method uses high oxygen pressure to accel-erate the test period while making use of lower test tempera-tures to protect addit

30、ive packages.5.6 The results from this test method may or may notcorrelate with those obtained by other OIT measurements suchas Test Method D3895 or Test Methods D4565.6. Apparatus6.1 Differential Scanning CalorimeterThermal analysisequipment capable of heating rates up to 20 6 1 C min and ofautomat

31、ically recording the differential heat flow between thetest sample and a reference sample is necessary. The equipmentmust be capable of measuring sample temperature to 61Cwhile maintaining a set temperature to 60.5 C.NOTE 1Modern computer-based instrumentation equipped with “iso-track” modes provide

32、s adequate specimen temperature control.6.2 Data-Presentation DeviceA printer, plotter, recorder,or other recording output device capable of displaying heatflow on the y-axis versus time on the x-axis as output signalsfrom differential scanning calorimeters in 6.1.6.3 High-Pressure DSC CellAunit cap

33、able of maintainingpressure up to 3.4 MPa 500 psig. The system shall beequipped with a pressure gage to monitor the internal pressureof the cell to permit manual release of pressure to maintaindesired level.NOTE 2The gage shall be accurate to 2 % at 3.4 MPa 500 psig.NOTE 3All pressures in this test

34、method are indicated relative toatmosphere pressurethat is, they are “gage” pressures.6.4 High-Pressure Oxygen Cylinder RegulatorA pressureregulator capable of regulating a pressure up to 5.5 MPa800 psi. The outlet of the cylinder is to be linked to thehigh-pressure cell using a clean stainless stee

35、l tube.6.5 Analytical Balance, 0.1-mg sensitivity.6.6 Specimen Holders, degreased aluminum pans, 6.0 to7.0-mm diameter.D5885/D5885M 1726.7 Core Hole Borer, cork borer or arch punch producing6.3-mm 0.25-in. disks.7. Reagents and Materials7.1 All chemical reagents used in this test method shall beanal

36、ytical grade unless otherwise specified.7.2 Hexane or Acetone, for cleaning specimen pans andstainless steel tubing, see 8.2.7.3 Indium (99.999 % Purity), for calibration purposes, see9.1.7.4 Oxygen, purity 99.5 % for the test atmosphere.8. Precautions8.1 Oxygen is a strong oxidizer that vigorously

37、acceleratescombustion. Keep oil and grease away from equipment usingor containing oxygen.8.2 The stainless steel tube connecting the high-pressurecell to the oxygen cylinder must be thoroughly cleaned byhexane (or acetone) and then dried before being connected tothe cell.8.3 The use of pressurized o

38、xygen requires appropriate andcareful handling procedures. The user of this test method shallbe familiar with the precautions described in Guide G88.9. Sampling9.1 The test sample is compression molded into sheetformat (thickness of 250 6 15 m) prior to analysis. Specimendisks (6.4-mm diameter) cut

39、from the sheet will have a weightof approximately 5 to 10 mg, depending on sample density.NOTE 4If the sample requires homogenization prior to analysis, oneof the procedures given in Appendix X1, Appendix X2,orAppendix X3is recommended. Poor sample uniformity will adversely affect testprecision.NOTE

40、 5If the sample contains a layer or layers of polymers other thanpolyolefins, the polyolefin may be tested separately from the entire crosssection. A recommended procedure is given in Appendix X4.9.2 Compression mold these assembled parts into a uniformplaque to a thickness of 0.25 mm 10 mil (see Pr

41、acticeD4703).NOTE 6The temperature at which molding takes place may be at orabove the test temperature of this test method. Prolonged exposure to airat these temperatures may induce a negative bias into OIT measurement.Molding should be performed at as low a temperature and as quickly aspossible to

42、minimize this bias.9.3 Cut test specimens from the plaque using a 6.3-mm0.25-in. bore hole cutter or punch.10. Calibration10.1 Using Test Method E967, temperature calibrate thedifferential scanning calorimeter using indium metal and aheating rate of 1 C min from 145 to 165 C.10.1.1 Perform the calib

43、ration step at least once a month orwhenever changes have occurred in the experimental setup.11. ProcedureNOTE 7Procedures for preparing the test specimen may be differentfor different polyolefin geosynthetic products, for example,geomembranes, geonets, geogrids, or geotextiles.11.1 Prepare a specim

44、en with a mass of 5 6 1 mg.11.2 Place the weighed specimen into the cleaned specimenpan.11.3 Place the specimen and reference pans into the cell.NOTE 8Open pans are used in this test method.11.4 Secure the top plate of the test chamber and tighten thecell system.11.5 Close the pressure release valve

45、 and the outlet valve.Open the inlet and pressurize the cell to 3.4 MPa 500 psioxygen. Close the inlet valve.11.6 Commence programmed heating of the specimen fromambient temperature to 150 C at a rate of 20 C min. Zerotime is taken at the initiation of the temperature program. Holdthe temperature is

46、othermally at 150 C until the oxidativeexothermic peak is detected. At the same time, the thermalcurve of the entire test is being recorded. Other test tempera-ture may be used, with the agreement of all parties concerned,but must be reported.11.7 A slight gain in pressure at the beginning of the te

47、st isanticipated as the temperature of the cell increases. Decreasethe pressure back to 3.4 MPa 500 psi by slightly opening thepressure release valve until the pressure comes down to3.4 MPa. Alternatively, if the pressure increase with an instru-ment is known, pressurize the test cell to a slightly

48、lower valueso that the pressure in the cell is 3.4 MPa 500 psi at theconclusion of the heating ramp cycle to test temperature.NOTE 9150 C is the temperature typically used for polyethylene-based material, and 170 C for polypropylene-based materials.NOTE 10The time to onset of oxidation varies with s

49、tabilizer packageand may be more than 900 min. For a first-time specimen, the isothermaltime period of 1000 min is suggested.NOTE 11The DSC cell should be cleaned by holding the cell at atemperature of 400 C for 3 min under air or oxygen atmosphere.12. Analysis Response12.1 Plot the data with the heat flow signal on the y-axis,versus time on the x-axis.12.2 Determine the value for OIT in the following manner:12.2.1 Plot data with a y-axis sensitivity sufficient to showthe full oxidative exotherm. A full-scale sensitivity o