1、Designation: D5885/D5885M 15Standard 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 under 3.4MPa of oxygen is greater than 30 min at 150C.1.5 The values stated in
5、 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 st
6、andard 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 s
7、tatements are given in Section 8.2. Referenced Documents2.1 ASTM Standards:2D3895 Test Method for Oxidative-Induction Time of Poly-olefins by Differential Scanning CalorimetryD4439 Terminology for GeosyntheticsD4491 Test Methods for Water Permeability of Geotextilesby PermittivityD4565 Test Methods
8、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 and Rhe-ologyE967 Test Method for
9、 Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodG88 Guide for Designing Systems for Oxygen Service3. Terminology3.1 Definitions:3.1.1 differential scanni
10、ng calorimetry (DSC), na tech-nique in which the difference 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.)3.1.2 geomemb
11、rane, nan essentially impermeable geosyn-thetic composed of one or more synthetic sheets. (See Termi-nology D4439.)3.1.2.1 DiscussionIn this test method, essentially imper-meable means that no measurable liquid flows through ageosynthetic when tested in accordance with Test MethodsD4491.3.1.3 geosyn
12、thetic, 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.)3.1.4 high-pressure differential scanning calorimetry(HPDSC), ndiffere
13、ntial scanning calorimetry in which thesubstance and reference material are exposed to a controlledsuperambient atmosphere.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 editio
14、n approved May 1, 2015. Published June 2015. Originallyapproved in 1995. Last previous edition approved in 2012 as D5885 06 (2012).DOI: 10.1520/D5885_D5885M-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
15、 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 States13.1.5 index test, na test procedure that may be used toestablish an order for a set of
16、specimens with respect to theproperty of interest.3.1.6 oxidative induction time (OIT), nthe elapsed timebetween first exposure to an oxidizing gas and the onset tooxidation of a material under isothermal conditions.3.1.6.1 DiscussionOxidative induction time is an indextest parameter dependent upon
17、a wide range of experimentalconditions 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 and the corresponding refer-ence material are heated from room temperature at a constantrate in a non-
18、purging, high-pressure oxygen environment at adefined pressure. When the specified temperature has beenreached, the specimen is then held at that temperature until theoxidative reaction is displayed on the thermal curve. The OITis the time interval from the start of the temperature programtest to th
19、e onset of the oxidative reaction.4.2 In this procedure, an elevated 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 150C, and the chamber pressure is to bemaintained at 3.4 MPa 500 psi
20、using a constant volume testcondition.5. Significance and Use5.1 The 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 us
21、edas a quality control measure to monitor the stabilization ingeosynthetics 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
22、.5.3 This test method is intended as an geosynthetic test. Useof the OIT value to estimate the lifetime of the geomembranefrom which the test specimen is taken is not addressed nor shallit be used for this purpose.5.3.1 The OIT measurement is an accelerated thermal agingtest and, as such, interpreta
23、tion of resulting data may bemisleading if done by an inexperienced 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 u
24、sed to select optimum resinformulations. Certain antioxidants, however, 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 Oxid
25、ation induction time is strongly dependent upontest temperature and 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
26、of these is the potential volatiliza-tion of additive packages used 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 pe
27、riod while making use of lower test tempera-tures to protect additive 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 analysise
28、quipment capable of heating rates up to 20 6 1C/min and ofautomatically 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 60.5C.NOTE 1Modern comput
29、er-based instrumentation equipped with “iso-track” modes provide 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 s
30、canning calorimeters in 6.1.6.3 High-Pressure DSC CellAunit capable 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 accura
31、te to 2 % at 3.4 MPa 500 psig.NOTE 3All pressures in this test 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 MPa 800psi. The outlet of the cylinder is to
32、be linked to the high-pressure cell using a clean stainless steel tube.6.5 Analytical Balance, 0.1-mg sensitivity.6.6 Specimen Holders, degreased aluminum pans, 6.0 to7.0-mm diameter.6.7 Core Hole Borer, cork borer or arch punch producing6.3-mm 0.25-in. disks.7. Reagents and Materials7.1 All chemica
33、l reagents used in this test method shall beanalytical grade unless otherwise specified.7.2 Hexane or Acetone, for cleaning specimen pans andstainless steel tubing, see 8.2 and 8.3.7.3 Indium (99.999 % Purity), for calibration purposes, see9.1.7.4 Oxygen, purity 99.5 % for the test atmosphere.D5885/
34、D5885M 1528. Precautions8.1 Oxygen is a strong oxidizer that vigorously 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 t
35、hen dried before being connected tothe cell.8.3 All specimen holders should be cleaned by washingwith hexane (or acetone) and then drying before being used inthe test.8.4 The use of pressurized oxygen requires appropriate andcareful handling procedures. The user of this test method shallbe familiar
36、with the precautions described in Guide G88.9. Sampling9.1 Using a bore hole cutter, cork borer, or punch, cutseveral 6.3-mm 0.25-in. round specimen from the geosyn-thetic test sample.9.2 Compression mold these assembled parts into a uniformplaque to a thickness of 0.25 mm 10 mil (see PracticeD4703)
37、.NOTE 4The 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 minimized th
38、is 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 1C/min from 145 to 165C.10.1.1 Perform the calibration step a
39、t least once a month orwhenever changes have occurred in the experimental setup.11. ProcedureNOTE 5Procedures for preparing the test specimen may be differentfor different polyolefin geosynthetic products, for example,geomembranes, geonets, geogrids, or geotextiles.11.1 Prepare a specimen with a mas
40、s 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 6Open 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 and the outl
41、et valve.Open the inlet and pressurize the cell to 4.3 MPa 500 psioxygen. Close the inlet valve.11.6 Commence programmed heating of the specimen fromambient temperature to 150C at a rate of 20C/min. Zero timeis taken at the initiation of the temperature program. Hold thetemperature isothermally at 1
42、50C until the oxidative exother-mic peak is detected.At the same time, the thermal curve of theentire test is being recorded. Other test temperature may beused, with the agreement of all parties concerned, but must bereported.11.7 A slight gain in pressure at the beginning of the test isanticipated
43、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 to 3.4MPa. Alternatively, if the pressure increase with an instrumentis known, pressurize the test cell to a slightly lower value sothat
44、the pressure in the cell is 3.4 MPa 500 psi at theconclusion of the heating ramp cycle to test temperature.NOTE 7150C is the temperature typically used for polyethylenebased material and 170C for polypropylene-based materials.NOTE 8The time to onset of oxidation varies with stabilizer packageand may
45、 be more than 900 min. For a first-time specimen, the isothermaltime period of 1000 min is suggested.NOTE 9The DSC cell should be cleaned by holding the cell at atemperature of 400C for 3 min under air or oxygen atmosphere.12. Analysis Response12.1 Plot the data with the heat flow signal on the y-ax
46、is,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 of 5 W/g isusually adequate.12.2.2 Extend the horizontal baseline generated prior to theonset to ox
47、idation.NOTE 10For the oxidation exotherm containing a small shoulder peakat the beginning of oxidation, a sigmoidal baseline may be moreappropriate than the straight baseline.12.2.3 Draw a tangent at the inflection point of the exother-mic peak and extend this tangent to intersect with the baseline
48、.12.2.4 The time at the intersection, measured from theinitiation of the temperature program from ambient tempera-ture is the onset of oxidative degradation and is taken as theOIT value.12.2.5 Measure the OIT as shown in Fig. 1.12.3 Report the OIT for a single specimen.NOTE 11If replicate tests are
49、required by the parties involved, a meanvalue shall be calculated as being representative of the material beingevaluated.13. Report13.1 Report the following information,13.1.1 Identification of the specimen,13.1.2 Mass and configuration of the test specimen,13.1.3 Method of conditioning the test specimen if differentfrom that specified herein,13.1.4 The single OIT value from the test, and13.1.5 The recorded pressure of oxygen during the isother-mal portion of the thermal curve.D5885/D5885M 15314. Precision and Bias314.1 An
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