1、Designation: D5721 08 (Reapproved 2018)Standard Practice forAir-Oven Aging of Polyolefin Geomembranes1This standard is issued under the fixed designation D5721; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 practice covers a means for estimating the resis-tance of polyolefin geomembranes to thermal aging in thepresence of air. O
3、nly 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 as
4、 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 asstandard. No other units of measurement are in
5、cluded in thisstandard.1.4 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, health, and environmental practices and deter-mine the applicability of regulatory l
6、imitations prior to use.1.5 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 Organizat
7、ion TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD638 Test Method for Tensile Properties of PlasticsD746 Test Method for Brittleness Temperature of Plasticsand Elastomers by ImpactD1238 Test Method for Melt F
8、low Rates of Thermoplasticsby Extrusion PlastometerD1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD1525 Test Method for Vicat Softening Temperature ofPlasticsD1790 Test Method for Brittleness Temperature of PlasticSheeting by ImpactD1870 Practice for Elevated Temperature
9、Aging Using aTubular Oven (Withdrawn 1998)3D3045 Practice for Heat Aging of Plastics Without LoadD4439 Terminology for GeosyntheticsE145 Specification for Gravity-Convection and Forced-Ventilation OvensF412 Terminology Relating to Plastic Piping Systems3. Terminology3.1 Definitions:3.1.1 For definit
10、ions of general terms used in this standard,refer to Terminology D4439.3.1.2 aging, nthe process of exposing materials to anenvironment for an interval of time.3.1.3 polyolefin, na polymer prepared by the polymeriza-tion of an olefin(s) as the sole monomer(s). (F412)3.1.4 Vicat softening pointthe te
11、mperature 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 uniform rate of temperature rise. (D1525)4. Significance and Use4.1 Under the severe conditions of this test, the specimensundergo deg
12、radation 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 conditions that are sufficiently severe to induce failure ofpolyolefin geomembranes within an abbreviated period oftime.1This practice i
13、s under the jurisdiction of ASTM Committee D35 on Geosyn-thetics and is the direct responsibility of Subcommittee D35.02 on EnduranceProperties.Current edition approved June 1, 2018. Published June 2018. Originallyapproved in 1995. Last previous edition approved in 2013 as D5721 08 (2013).DOI: 10.15
14、20/D5721-08R18.2For 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 Document Summary page onthe ASTM website.3The last approved version of this historical
15、standard is referenced onwww.astm.org.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.14.3 The rate of change of a particular property as a functionof temperature may be evaluated using the temperatures andtimes outlin
17、ed in Practice D3045.4.4 Any correlation between this practice and natural life ofthese materials must be determined for the particular applica-tion in which the materials are to be used.4.5 Air-oven aging can be used to evaluate and compare theperformance of various heat stabilizer packages.5. Appa
18、ratus5.1 OvenA controlled, forced-ventilation oven with sub-stantial fresh air intake is recommended. Oven apparatus shallbe in accordance with Type 11B in Specification E145.NOTE 1Cross contamination has been known to occur in rubberproducts. It is not known if it can occur in semi-crystalline ther
19、moplastics.When it is necessary to avoid contamination among specimens ormaterials, a tubular oven method such as Practice D1870 may bedesirable.5.2 Temperature Measuring DeviceA thermocouple orthermometer adequate to cover the range being tested andaccurate to at least 60.5 C.6. Sampling6.1 Samplin
20、g shall be in accordance with the ASTM testmethods for the specific properties to be determined.7. Conditioning7.1 Conduct initial tests in the standard laboratory atmo-sphere as specified in Practice D618, and with specimensconditioned in accordance with the requirements of the ASTMtest method for
21、determining the specific property or propertiesrequired.7.2 When required, conditioning of specimens followingexposure at elevated temperature and prior to testing, unlessotherwise specified, shall be in accordance with Practice D618.8. Procedure8.1 Allow the oven to equilibrate at the test temperat
22、ure.The temperature shall be below the Vicat softening point of 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 tempe
23、rature.NOTE 2Certain metals are known to affect the thermal endurance 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
24、 Rotate the shelves from top to bottom and from front toback once 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 c
25、onditioning.9. Potential Tests9.1 The following properties may be appropriate for evalu-ating the effects of oven exposure:9.1.1 Tensile properties (see Test Method D638),9.1.2 Melt flow index (see Test Method D1238),9.1.3 Density (see Test Method D1505),9.1.4 Tensile impact (see Test Method D746),
26、and9.1.5 Brittleness temperature (see Test Method D1790).10. 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# 3100 (1)where:O = original value, andA = value after aging.NOTE 3Since the values of
27、some properties may increase as a functionof exposure time, a positive change shows an increase while a negativechange 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 give
28、n property.11. Report11.1 Report the following information:11.1.1 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
29、in the testspecimens,11.1.5 Type of oven used,11.1.6 Exposure 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; polyolefinD5
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