ASTM D7238-06(2012)
(Test Method)Standard Test Method for Effect of Exposure of Unreinforced Polyolefin Geomembrane Using Fluorescent UV Condensation Apparatus
Standard Test Method for Effect of Exposure of Unreinforced Polyolefin Geomembrane Using Fluorescent UV Condensation Apparatus
SIGNIFICANCE AND USE
5.1 The use of this apparatus is intended to induce property changes associated with the end use conditions, including the effects of the UV portion of sunlight, moisture, and heat. Exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack, and saltwater exposure.Note 3—Refer to Practice G151 for cautionary guidance applicable to laboratory weathering devices.
5.2 Variation in results may be expected when operating conditions are varied within the accepted limits of this method.
5.3 Test data for one thickness of a geomembrane can not be used as data for other thickness geomembranes made with the same formula (polymer, pigment and stabilizers) since the degradation is thickness related.Note 4—It is recommended that a similar material of known performance (a control) be exposed simultaneously with the test material to provide a standard for comparative purposes. When control material is used in the test program, it is recommended only one coupon be used for each UV exposure period to allow for OIT testing.
SCOPE
1.1 This standard covers the specific procedures and test conditions that are applicable for exposure of unreinforced polyolefin geomembranes to fluorescent UV radiation and condensation.Note 1—Polyolefin geomembranes include high density polyethylene (HDPE), linear low density polyethylene (LLDPE), flexible polyproplyene (fPP), etc.
1.2 Test specimens are exposed to fluorescent UVA 340 lamps under controlled environmental conditions. UVA 340 lamps are standard for this method. Note 2—Other types of fluorescent UV lamps, such as UVB-313, can also be used based upon discussion between involved parties. However, if the test is ran with another type of fluorescent UV lamps, such as UVB-313, this should be considered as a deviation from the standard and clearly stated in the test report. UVB-313 and UVA-340 fluorescent lamps generate different amount of radiant power in different wavelength ranges; thus, the photochemical effects caused by these different lamps may vary.
1.3 This method covers the conditions under which the exposure is to be performed and the test methods for evaluating the effects of fluorescent UV, heat and moisture in the form of condensation on geomembranes. General guidance is given in Practices G151 and G154.
1.4 The values listed in SI units are to be regarded as the standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D7238 −06 (Reapproved 2012)
Standard Test Method for
Effect of Exposure of Unreinforced Polyolefin
Geomembrane Using Fluorescent UV Condensation
Apparatus
This standard is issued under the fixed designation D7238; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This standard covers the specific procedures and test 2.1 ASTM Standards:
D1238 Test Method for Melt Flow Rates of Thermoplastics
conditions that are applicable for exposure of unreinforced
polyolefin geomembranes to fluorescent UV radiation and by Extrusion Plastometer
D5885 Test Method for Oxidative Induction Time of Poly-
condensation.
olefin Geosynthetics by High-Pressure Differential Scan-
NOTE 1—Polyolefin geomembranes include high density polyethylene
ning Calorimetry
(HDPE), linear low density polyethylene (LLDPE), flexible polyproply-
D6693 Test Method for Determining Tensile Properties of
ene (fPP), etc.
Nonreinforced Polyethylene and Nonreinforced Flexible
1.2 Test specimens are exposed to fluorescent UVA 340
Polypropylene Geomembranes
lamps under controlled environmental conditions. UVA 340
G113 Terminology Relating to Natural andArtificial Weath-
lamps are standard for this method.
ering Tests of Nonmetallic Materials
NOTE 2—Other types of fluorescent UV lamps, such as UVB-313, can
G151 Practice for Exposing Nonmetallic Materials inAccel-
also be used based upon discussion between involved parties. However, if
erated Test Devices that Use Laboratory Light Sources
the test is ran with another type of fluorescent UV lamps, such as
G154 PracticeforOperatingFluorescentLightApparatusfor
UVB-313, this should be considered as a deviation from the standard and
UV Exposure of Nonmetallic Materials
clearly stated in the test report. UVB-313 and UVA-340 fluorescent lamps
generatedifferentamountofradiantpowerindifferentwavelengthranges; G156 Practice for Selecting and Characterizing Weathering
thus, the photochemical effects caused by these different lamps may vary.
Reference Materials
1.3 This method covers the conditions under which the
3. Terminology
exposureistobeperformedandthetestmethodsforevaluating
3.1 Definitions: (According to Terminology G113).
the effects of fluorescent UV, heat and moisture in the form of
3.1.1 control, n—Amaterialwhichisofsimilarcomposition
condensation on geomembranes. General guidance is given in
and construction to the test material used for comparison,
Practices G151 and G154.
exposed at the same time.
1.4 The values listed in SI units are to be regarded as the
3.1.2 irradiance, n—the radiant power per unit area incident
standard.
on a receiver, typically reported in units of W/(m .nm) at
1.5 This standard does not purport to address all of the 2
specifiedwavelengthofmeasurementorinW/m inaspecified
safety concerns, if any, associated with its use. It is the
spectral range.
responsibility of the user of this standard to establish appro-
3.1.3 reference material, n—A material with known perfor-
priate safety and health practices and determine the applica-
mance.
bility of regulatory limitations prior to use.
3.1.4 ultraviolet regions, n—The UVregion of the spectrum
is divided into three regions: UVA, radiation in wavelengths
This test method is under the jurisdiction of ASTM Committee D35 on
Geosynthetics and is the direct responsibility of Subcommittee D35.02 on Endur- For referenced ASTM standards, visit the ASTM website, www.astm.org, or
ance Properties. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved July 1, 2012. Published July 2012. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
D7238-06R2012 the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7238−06 (2012)
between 315 nm and 400 nm; UVB, radiation in wavelengths 6.3 The apparatus must include a feed-back-loop controller
between 280 nm and 315 nm; and UVC, radiation in wave- and be capable of controlling the irradiance level within the
lengths shorter than 280 nm (Ref. CIE Publication No. 20 guidelines set in Practice G154, Table X2.3, Operational
(1972)). Fluctuations On Exposure Conditions.
6.4 Exposure Chamber Location:
4. Summary of Test Method
6.4.1 Theapparatusshallbelocatedinanareamaintainedat
4.1 Geomembrane coupons are exposed to repetitive cycles
temperature range between 18 and 27°C (64 and 81°F)
consisting of ultraviolet radiation at a specified temperature
measured at a maximum distance of 150 mm (5.9 in) from the
followedbymoistureintheformofcondensationataspecified
plane door of the apparatus.
temperature in the absence of ultraviolet radiation.
6.4.2 It is recommended that the apparatus be located at
least0.3m(12in)fromwallsorothertestdevices.Nearbyheat
4.2 The UV source is provided by fluorescent UVA-340
sources, such as ovens or heated test devices, shall be avoided
lamps, with lamp emissions peaking at 343 nm.
or shielded, because such sources can influence the results.
4.3 Water vapor shall be generated by heating water and
6.4.3 The room where the apparatus is located shall be
filling the chamber with hot vapor, which then is made to
adequately ventilated to remove the heat and moisture pro-
condense on the front of the test coupons. The reverse side of
duced and to maintain the temperatures specified in 6.4.1.
the coupons is exposed to the cooling influence of ambient
6.5 Instrument Calibration:
room air.
6.5.1 To ensure standardization and accuracy, the instru-
4.4 While this standard prescribes a particular set of expo-
ments associated with the exposure apparatus (that is, timers,
sure conditions, such conditions may be varied by agreement
thermometers, UV sensors, radiometers) require recurrent cali-
betweenthepartiesinvolvedintheagreementorcontract.Such
bration to ensure repeatability of test results. The calibration
variation may include the irradiance, the selection of the
frequency recommended by the equipment manufacturer
fluorescent UV lamps; the duration of the UV and condensa-
should be used.
tionexposureperiods;thetemperatureofUVexposure;andthe
NOTE5—Itisrecommendedthataweatheringreferencematerialshould
temperature of the condensation exposure.
be evaluated at least once per year to assess the operation of the device.
4.5 The periodically removed coupons are cut into test
Practice G156 describes procedures for selecting and characterizing
specimens, appropriately tested and the results compared to
weathering reference materials used to establish consistency of operating
conditions in a laboratory accelerated test.
unexposed samples for determination of a percent retained for
each property evaluated
7. Test Coupons
7.1 The number of coupons should be sufficient to produce
5. Significance and Use
five Test Methods D6693 specimens from the exposure areas
5.1 The use of this apparatus is intended to induce property
for each exposure period.
changes associated with the end use conditions, including the
7.2 Prepare the test coupons so that the longer dimension of
effects of the UV portion of sunlight, moisture, and heat.
the test coupon is the machine direction of the test material.
Exposuresarenotintendedtosimulatethedeteriorationcaused
by localized weather phenomena, such as atmospheric
7.3 Since the thickness of a coupon may markedly affect the
pollution, biological attack, and saltwater exposure.
results, thickness of the test and control coupon shall be within
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