1、Designation: D 5721 95 (Reapproved 2002)Standard Practice forAir-Oven Aging of Polyolefin Geomembranes1This standard is issued under the fixed designation D 5721; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. 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 practice covers a means for estimating the resis-tance of polyolefin geomembranes to thermal aging in thepresence of air
3、. Only the procedure for heat exposure isspecified, not the test method or specimen. The effect of heaton any particular property may be determined by selection ofthe appropriate test method and specimen.1.2 This practice should be used as a guide to comparethermal aging characteristics of materials
4、 as measured by thechange in some property of interest. This practice does notpredict thermal aging characteristics where interactions be-tween stress, environment, temperature, and time controlfailure.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not pur
5、port 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 Documents2.1 ASTM Standards:D 6
6、18 Practice for Conditioning Plastics and ElectricalInsulating Materials for Testing2D 638 Test Method for Tensile Properties of Plastics2D 746 Test Method for Brittleness Temperature of Plasticsand Elastomers by Impact2D 1238 Test Method for Flow Rates of Thermoplastics byExtrusion Plastometer2D 15
7、05 Test Method for Density of Plastics by Density-Gradient Technique2D 1525 Test Method for Vicat Softening Temperature ofPlastics2D 1790 Test Method for Brittleness Temperature of PlasticFilm by Impact2D 1822 Test Method for Tensile-Impact Energy to BreakPlastics and Electrical Insulating Materials
8、2D 1870 Practice for Elevated Temperature Aging Using aTubular Oven2D 3045 Practice for Heat Aging of Plastics Without Load3D 4439 Terminology for Geotextiles4E 145 Specifications for GravityConvection andForcedVentilation Ovens5F 412 Terminology Relating to Plastic Piping Systems6F 869 Definitions
9、of Terms Relating to Athletic Shoes andBiomechanics73. Terminology3.1 Definitions:3.1.1 aging, nthe process of exposing materials to anenvironment for an interval of time. (F 869)3.1.2 geomembrane, nan essentially impermeable geo-synthetic composed of one or more synthetic sheets.(D 4439)3.1.3 polyo
10、lefin, na polymer prepared by the polymeriza-tion of an olefin(s) as the sole monomer(s). (F 412)3.1.4 Vicat softening pointthe temperature at which aflat-ended needle of 1 mm2circular cross section will penetratea thermoplastic specimen to a depth of 1 mm under a specifiedload using a selected unif
11、orm rate of temperature rise.(D 1525)4. Significance and Use4.1 Under the severe conditions of this test, the specimensundergo degradation at a rate that is a function of the thermalendurance of the geomembrane under examination.4.2 The elevated temperature for this practice should repre-sent condit
12、ions that are sufficiently severe to induce failure ofpolyolefin geomembranes within an abbreviated period oftime.4.3 The rate of change of a particular property as a functionof temperature may be evaluated using the temperatures andtimes outlined in Practice D 3045.4.4 Any correlation between this
13、practice and natural life ofthese materials must be determined for the particular applica-tion in which the materials are to be used.1This practice is under the jurisdiction of ASTM Committee D35 on Geosyn-thetics and is the direct responsibility of Subcommittee D35.02 on EnduranceProperties.Current
14、 edition approved April 15, 1995. Published June 1995.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 08.02.4Annual Book of ASTM Standards, Vol 04.13.5Annual Book of ASTM Standards, Vol 14.02.6Annual Book of ASTM Standards, Vol 08.04.7Annual Book of ASTM Standards, Vol
15、15.07.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.5 Air-oven aging can be used to evaluate and compare theperformance of various heat stabilizer packages.5. Apparatus5.1 OvenA controlled, forcedventilation oven with sub-stantia
16、l fresh air intake is recommended. Oven apparatus shallbe in accordance with Type 11B in Specifications E 145.NOTE 1Cross contamination has been known to occur in rubberproducts. It is not known if it can occur in semi-crystalline thermoplastics.When it is necessary to avoid contamination among spec
17、imens ormaterials, a tubular oven method such as Practice D 1870 may bedesirable.5.2 Temperature Measuring DeviceA thermocouple orthermometer adequate to cover the range being tested andaccurate to at least 60.5C.6. Sampling6.1 Sampling shall be in accordance with the ASTM testmethods for the specif
18、ic properties to be determined.7. Conditioning7.1 Conduct initial tests in the standard laboratory atmo-sphere as specified in Practice D 618, and with specimensconditioned in accordance with the requirements of the ASTMtest method for determining the specific property or propertiesrequired.7.2 When
19、 required, conditioning of specimens followingexposure at elevated temperature and prior to testing, unlessotherwise specified, shall be in accordance with PracticeD 618.8. Procedure8.1 Allow the oven to equilibrate at the test temperature.The temperature shall be below the Vicat softening point of
20、thematerial.8.2 Suspend the specimens for exposure below an ovenshelf in a way to maintain a distance of at least 20 mm betweenspecimens and to allow for the entire shelf with specimens tobe removed. Age for the specified time and temperature.NOTE 2Certain metals are known to affect the thermal endu
21、rance ofsome polyolefins. Therefore, direct contact of the specimens with metalshall be minimized.8.3 Inspect the specimens weekly to ensure that the speci-mens have remained properly mounted. Note any visualchanges of the specimens.8.4 Rotate the shelves from top to bottom and from front toback onc
22、e a week to ensure even exposure.8.5 At the end of an aging interval, remove a set ofspecimens and allow them to cool. Test the specimens for theselected property in accordance with the appropriate testmethod, including provisions for conditioning.9. Potential Tests9.1 The following properties may b
23、e appropriate for evalu-ating the effects of oven exposure:9.1.1 Tensile properties (see Test Method D 638),9.1.2 Melt flow index (see Test Method D 1238),9.1.3 Density (see Test Method D 1505),9.1.4 Tensile impact (see Test Method D 746), and9.1.5 Brittleness temperature (see Test Method D 1790).10
24、. Calculation10.1 Express the results of the aging test as a percentage ofthe change in each physical property, calculated as follows:change,%5 A 2 O!/O# 3 100 (1)where:O = original value, andA = value after aging.NOTE 3Since the values of some properties may increase as afunction of exposure time,
25、a positive change shows an increase while anegative change shows a decrease in the property value.10.2 Alternatively, the time to failure can be determinedbased on a failure criteria such as brittleness, or on a percent-age change of a given property.11. Report11.1 Report the following information:1
26、1.1.1 Geomembrane type, thickness and specimen prepa-ration procedure,11.1.2 Pre-conditioning and post-conditioning proceduresfollowed,11.1.3 Test methods utilized for evaluation of each property,11.1.4 Observations of any visible changes in the testspecimens,11.1.5 Type of oven used,11.1.6 Exposure
27、 temperature and times used,11.1.7 Mean and standard deviation for results calculatedaccording to 10.1, and11.1.8 Mean time to failure and failure criteria for resultsgenerated in 10.2.12. Keywords12.1 geomembrane; oven aging; polyolefinD 5721 95 (2002)2ASTM International takes no position respectin
28、g the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standa
29、rd is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Internationa
30、l Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.Th
31、is standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 5721 95 (2002)3
