1、Designation: D750 12 (Reapproved 2017)Standard Practice forRubber Deterioration Using Artificial Weathering Apparatus1This standard is issued under the fixed designation D750; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This practice covers specif
3、ic variations in the testconditions and procedures that shall be applicable whenPractice G151 plus either Practice G152, G153, G154,orG155are employed for exposure of vulcanized rubber compounds. Italso covers the preparation of test specimens and the evaluationof results.1.2 The values stated in SI
4、 units are to be regarded asstandard. The values given in parentheses are for informationonly.1.3 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 and health pra
5、ctices and determine the applica-bility of regulatory limitations prior to use.1.4 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 a
6、nd Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D412 Test Methods for Vulcanized Rubber and Thermoplas-tic ElastomersTensionD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Stand
7、ard Compounds and PreparingStandard Vulcanized SheetsD3183 Practice for RubberPreparation of Pieces for TestPurposes from ProductsD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Black ManufacturingIndustriesG151 Practice for Exposing Nonmetallic Materials in
8、 Accel-erated Test Devices that Use Laboratory Light SourcesG152 Practice for Operating Open Flame Carbon Arc LightApparatus for Exposure of Nonmetallic MaterialsG153 Practice for Operating Enclosed Carbon Arc LightApparatus for Exposure of Nonmetallic MaterialsG154 Practice for Operating Fluorescen
9、t Ultraviolet (UV)Lamp Apparatus for Exposure of Nonmetallic MaterialsG155 Practice for Operating Xenon Arc Light Apparatus forExposure of Non-Metallic Materials3. Significance and Use3.1 This practice describes procedures to use in determiningthe effects of an open-flame carbon-arc light source, an
10、enclosed carbon-arc light source, a xenon-arc light source, or afluorescent UV source along with heat and moisture on rubberspecimens held in a jig or holder with or without a specifiedstrain. The purpose is to attempt to accelerate the effectsproduced by light, heat, and moisture in the natural env
11、iron-ment. Exposures are not intended to simulate the deteriorationcaused by localized weather phenomena, such as atmosphericpollution, biological attack, and saltwater exposure. The Sig-nificance and Use section in Practice G151 and the standard forthe appropriate apparatus, that is, Practices G152
12、, G153, G154,or G155 should be consulted for additional information onsignificance and use of the exposure tests.3.2 The primary criterion used in estimating resistance toweathering is the percentage decrease in tensile strength and inelongation at break. A supplementary criterion for estimatingresi
13、stance to weathering is the observed extent of surfacecrazing and cracking.3.3 Results obtained by use of these test procedures shouldnot be represented as equivalent to those of any naturalexposure test until the degree of quantitative correlation hasbeen established for the material in question.3.
14、4 Because of differences in the spectral power distribu-tions of the exposure sources as well as the other conditions inthe different types of laboratory weathering tests, the differentprocedures may not result in the same performance rankings or1This practice is under the jurisdiction of ASTM Commi
15、ttee D11 on Rubber andRubber-like Materials and is the direct responsibility of Subcommittee D11.15 onDegradation Tests.Current edition approved June 1, 2017. Published July 2017. Originally approvedin 1943. Last previous edition approved in 2012 as D750 12. DOI: 10.1520/D0750-12R17.2For referenced
16、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.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho
17、hocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Orga
18、nization Technical Barriers to Trade (TBT) Committee.1types of failure modes of the materials. Comparisons shall notbe made of relative stabilities of materials exposed in differenttypes of apparatus.3.5 When conducting exposures in devices that use labora-tory light sources, it is important to cons
19、ider how well theartificial weathering conditions will reproduce propertychanges and failure modes caused by end-use environments onthe materials being tested.3.6 Practices G151, G152, G153, G154, and G155 recom-mend that a similar material of known performance (a control)be exposed simultaneously w
20、ith the test specimen to provide astandard for comparative purposes. Preferably, a control mate-rial known to have poor durability as well as one that has gooddurability should be used. The reason for using a control is thatreproducibility in ranking stabilities is usually better thanreproducibility
21、 of absolute changes. Therefore, the use ofcontrols is particularly important when test materials are notbeing compared with one another.4. Apparatus4.1 Historically, this standard utilized carbon arc exposureapparatus in a test method for rubber deterioration. The optionsof using either xenon arc o
22、r fluorescent UV exposure apparatushave been added in order to update the tests with the use oflight sources that give a better representation of the effects ofsolar radiation than carbon arcs. The xenon arc source withdaylight filters, which conforms to Practice G155, gives theclosest simulation of
23、 the full spectrum of terrestrial solarradiation, and the fluorescent UV/condensation test apparatuswith the UVA-340 fluorescent UV lamp, which conforms toPractice G154, closely simulates the UV of terrestrial solarradiation in the 300 to 360 nm region.4.2 The type of carbon-arc exposure apparatus p
24、referred isthe filtered open flame carbon arc, which conforms withPractice G152, but the enclosed carbon arc apparatus conform-ing with Practice G153 may be used by mutual consent of theconcerned parties.5. Test Specimens5.1 Unless otherwise mutually agreed upon, test specimensprepared especially fo
25、r this test or cut from the material to beevaluated shall be three tension test replicates prepared inaccordance with Practices D3182 and D3183. An additionalthree tension test replicates shall be prepared and stored fortesting in accordance with 7.1.3. Unless otherwise mutuallyagreed upon, the spec
26、imens should have a maximum thicknessof 0.75 mm (0.030 in.) and a minimum thickness 0.60 mm(0.025 in.).5.2 If evaluation is limited only to visual observation, thenspecimens of any thickness may be used and the thickness shallbe included in the report. Dimensions of the specimens are notcritical but
27、 previous practice called for specimens 75 mm(3 in.) wide by 150 mm (6 in.) in length.5.3 Exposing at least duplicate sets, preferably triplicatesets, of test specimens whenever possible is recommended.5.4 Specimens cut from rubber products may be buffed.6. Procedure6.1 Firmly fasten the test specim
28、ens in a jig or holder thatpermits exposure either with or without elongation. Whileexposures are usually made without elongation of the testspecimen, when mutually agreed upon, any specified amountof elongation may be employed but this must be reported in theresults of the test.6.2 The four exposur
29、e procedures use different types ofexposure sources and test conditions. Therefore, they mayproduce different test results. They shall not be used inter-changeably without supporting data that demonstrates equiva-lency of the procedures for the materials tested. Choice of thetype of apparatus and du
30、ration of exposure shall be by mutualagreement among the interested parties.6.3 For the allowed operational fluctuations of the specifiedset points for irradiance, temperature, and relative humidity,refer to Table A3.1 in Practice G151. If the actual operatingconditions do not comply with the maximu
31、m allowable fluc-tuations in Table A3.1 after the equipment has stabilized,discontinue the test and correct the cause of the problem beforecontinuing.6.4 Specimens should be confined to an exposure area inwhich the irradiance is at least 90 % of the irradiance at thecenter of the exposure area. Unle
32、ss it is known that irradianceuniformity meets this requirement, use one of the proceduresdescribed in Practice G151, Appendix X2 to ensure equalradiant exposure on all specimens or to compensate fordifferences within the exposure chamber. If the specimens donot completely fill the racks, fill the e
33、mpty spaces with blankmetal panels to maintain the test conditions within the cham-ber.6.5 The apparatus shall be operated continuously. However,if the test needs to be interrupted to perform routine mainte-nance or inspection, it should be during a dry period.6.6 Procedure for Exposure in Open Flam
34、e Carbon ArcApparatus (Practice G152) or Enclosed Carbon Arc Apparatus(Practice G153)Unless otherwise specified, use the follow-ing operating conditions:6.6.1 The open flame carbon arc apparatus and the enclosedcarbon arc apparatus shall be used with daylight type filters andconform with the spectra
35、l power distribution specifications inPractices G152 and G153, respectively.6.6.2 Unless otherwise mutually agreed upon or specified,operate with a cycle cam of 102 min light followed by 18 minof light plus water spray on the front surface of the sample (seeNote 1). The water spray temperature is ty
36、pically 21 6 5C,but may be lower if ambient water temperature is low and aholding tank is not used to store purified water.NOTE 1This cycle is recommended only because it has long historicalusage, not because it has been established for technical reasons assuperior.6.6.3 Set the uninsulated black pa
37、nel temperature (BPT) at63C during the dry period of exposure to light.6.6.4 Set the relative humidity at 60 % during the dry periodof exposure to light.D750 12 (2017)26.7 Procedure for Exposure in Xenon Arc Light Apparatus(Practice G155)Unless otherwise specified, use the follow-ing operating condi
38、tions:6.7.1 The xenon arc shall be used with daylight type filtersand conform with the spectral power distribution specificationsin Practice G155.6.7.2 Set the irradiance level at 0.55 W/(m2nm) at 340 nm.For equivalent broad band irradiance levels at 300 to 400 nmand 300 to 800 nm, consult the manuf
39、acturer of the apparatus.6.7.3 The default exposure cycle shall be 102 min light onlyfollowed by 18 min light plus either water spray on the frontsurface or immersion in water.3NOTE 2Water spray and immersion in water are different kinds ofmoisture and frequently produce different results. Spray wat
40、er can be freshor re-circulated from a holding tank. The temperature of the spray wateris uncontrolled and for fresh water is typically 21 6 5C. Re-circulatedspray water can be at a higher temperature. Immersion water is generallyin a holding tank for recirculation. The uncontrolled temperature of t
41、here-circulated immersion water during operation of the weathering deviceis typically 40 6 5C.6.7.4 Set the uninsulated black panel temperature (BPT) at63C during the dry period of exposure to light. For theequivalent insulated black panel temperature black standardtemperature (BST), consult the man
42、ufacturer of the apparatus.6.7.5 Relative humidity shall be set at 60 % during the dryperiod of exposure to light in xenon arc apparatus that providesfor control of relative humidity.6.7.6 The chamber air temperature shall be set at 44C inequipment that provides for adjustment of the chamber airtemp
43、erature.6.8 Procedure for Exposure in Fluorescent UV/Condensation Apparatus (Practice G154)Unless otherwisespecified, use the following operating conditions:6.8.1 Use fluorescent UVA-340 lamps that comply with thespectral power distribution specifications in Practice G154.6.8.2 The irradiance level
44、shall be set at 0.77 W/(m2nm) at340 nm in apparatus with irradiance control.6.8.3 The exposure cycle shall be8hUVatanuninsulatedblack panel temperature of 60C followed by a dark period of4 h with wetting by condensation at an uninsulated black paneltemperature of 50C.NOTE 3Wetting by condensation ma
45、y not be applicable to specimensof insulating materials having a thickness greater than 25 mm because ofinadequate heat transfer.NOTE 4The presence of ozone should be avoided since it cancontribute to the crazing and cracking caused by light, heat, and moisture.6.9 The periods of exposure shall be a
46、 mutually agreed uponspecified time or amount of radiant energy. It shall be deter-mined by one of the following procedures (for guidance onminimum exposure, consult Section 8 of Practice G151):6.9.1 A mutually agreed upon specified number of hours, or6.9.2 The number of hours of exposure required t
47、o producemutually agreed upon minimum detectable changes in eitherthe test specimen or an agreed upon standard sample.7. Interpretation of Results7.1 The effects of exposure shall be determined in thefollowing manner:7.1.1 At the conclusion of the exposure interval the speci-mens shall be removed fr
48、om the exposure test apparatus andexamined visually for indications of crazing and cracking. Thenumber and degree of cracks and crazes shall be reported by amutually agreed upon method.7.1.2 The tensile strength and ultimate elongation of thesereplicates shall be determined in accordance with Test M
49、ethodsD412.7.1.3 For the purpose of comparison, tensile strength andelongation of duplicate unexposed specimens of the samematerial shall be determined at the time the exposed replicatesare tested.8. Report8.1 In addition to the report requirements of Practice G151,report the following additional information:8.1.1 Any variations from the specified conditions,8.1.2 Description and dimensions of specimens,8.1.3 Number of cracks and degree of crazing or cracking ofthe specimens,8.1.4 Percentage of elongation during exposure, if any,8.1.5 Tensile strength in kilopa
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