1、Designation: F 484 08Standard Test Method forStress Crazing of Acrylic Plastics in Contact with Liquid orSemi-Liquid Compounds1This standard is issued under the fixed designation F 484; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method cove
3、rs determination of the crazingeffect that a liquid or semi-liquid test compound will have ontransparent acrylic plastic material that is under bending stress.1.2 Three types of acrylic material are covered. One, two, orall of the materials shall be used in the test, as specified by theprocuring age
4、ncy. When not specified otherwise, all three typesof acrylic shall be used in the test.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standar
5、d.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced
6、 Documents2.1 ASTM Standards:2D 1193 Specification for Reagent Water2.2 Military Standards:MIL-PRF-5425 Plastic Sheet, Acrylic, Heat Resistant3MIL-PRF-8184 Plastic Sheet, Acrylic, Modified3MIL-PRF-25690 Plastic, Sheets and Formed Parts, Modi-fied Acrylic-Basic, Monolithic, Crack Propagation Resis-ta
7、nt33. Terminology3.1 Definitions:3.1.1 crazea minute surface crack, sometimes hairline insize.NOTE 1Hairline craze cracks are very difficult to see except withcareful inspection under properly oriented light.3.1.2 cracka fracture or tear.4. Types4.1 Type A, cast acrylic material shall conform to MIL
8、-PRF-5425, Finish A.4.2 Type B, cast acrylic material shall conform to MIL-PRF-8184, Finish B.4.3 Type C, stretched acrylic material shall conform toMIL-PRF-25690.5. Apparatus5.1 Stress ApparatusThe means of stressing the acrylicplastic test specimen bars shall be as shown in Fig. 1.6. Test Specimen
9、s6.1 The test specimens shall be machined from 0.25 60.025 in. (6.4 6 0.64 mm) thick polished acrylic plastic sheetconforming to the applicable specification.6.2 The test specimens shall be 1 6 0.03 in. (25.4 6 0.8mm) wide by 7 6 0.05 in. (177.8 6 1.27 mm) long by 0.25 60.025 in. (6.4 6 0.64 mm) thi
10、ck. Edges shall be a smoothmachined surface without cracks.7. Conditioning7.1 Do not anneal Type C acrylic specimens.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.07 onQualification Testing of Aircraft
11、Cleaning Materials.Current edition approved April 1, 2008. Published April 2008. Originallyapproved in 1977. Last previous edition approved in 2002 as F 484 02.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of
12、 ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5098, Attn: NPODS.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, Wes
13、t Conshohocken, PA 19428-2959, United States.7.2 Anneal Type A and Type B acrylic test specimens aftermachining by heating in a circulating air oven at 195 6 5F (916 3C) for 512 h. Cool the specimens to room temperature inthe oven using a uniform cooling rate of 50F (28C)/h.7.3 Condition all specime
14、ns at 75 6 10F and 50 6 5%relative humidity for a minimum of 24 h just before testing.8. Procedure8.1 Test two specimens of each acrylic material specified foreach of the test compounds being evaluated.8.2 Conduct the test at a temperature of 75 6 10F (23 65C).8.3 Carefully load the acrylic specimen
15、 as a cantilever beamas shown in Fig. 1. Unless otherwise specified, the followingare recommended stress levels:8.3.1 Type A specimens shall be stressed to an outer fiberstress of 3000 psi (20 685 kPa).8.3.2 Type B specimens shall be stressed to an outer fiberstress of 3500 psi (24 132 kPa).8.3.3 Ty
16、pe C specimens shall be stressed to an outer fiberstress of 4500 psi (31 027 kPa).8.4 Allow the specimen to remain under the designatedstress for 10 min; then examine under the lighting and visualinspection conditions shown in Fig. 1 to be sure no crazing hasinitiated. If crazing has occurred, subst
17、itute another acrylic testspecimen.8.5 With the test specimen again under the designated load,place an absorbent cotton or flannel swatch,12 to58 in. (12.7to 15.9 mm) square, on the tension surface (top) of the crazetest specimen directly over the fulcrum. Position the cotton orflannel swatch in the
18、 middle of the specimen so there is a clearspace along each edge to avoid initiating crazing at the edge.8.6 Completely soak the cotton or flannel swatch with thetest fluid or compound to be evaluated. Keep the swatch moistwith the test compound for the duration of the test. Take careto avoid spread
19、ing or smearing the test compound to the edgeof the test specimen. No test compound should contact theacrylic specimen within18 in. (3.2 mm) of the edge.8.7 The test duration shall be 8 h. After test compoundexposures of 30 min, 1 h, 2 h, 4 h, and 8 h, inspect thespecimens for crazing or degradation
20、. Do this by sliding themoist swatch approximately 2 in. toward the loaded end.Carefully wipe the test area clean. A clean cloth wet withdistilled or deionized water conforming to SpecificationD 1193, Type IV water may be used to remove dry residue ifnecessary in the cleaning operation.8.8 Carefully
21、 examine the top (tension) surface of thespecimen in the manner shown in Fig. 1 for any evidence ofcrazing, cracks, or etching effect on the polished surface of theacrylic test specimen.8.8.1 Use a single point source of concentrated columatedlight, such as a large-size microscopic illuminator, for
22、inspec-tion.8.9 Disregard crazing that initiates at the edge of thespecimen unless it grows and extends across the specimen. Inthis case, the time of the meeting of the crazing from the edgesshall be taken as the end point of the test. Terminate the test assoon as crazing or degradation is observed,
23、 even though thefull 8-h duration has not been reached.Load: outer fiber stressouter fiber stressouter fiber stress3000 psi (20 685 kPa) Type A acrylic3500 psi (24 132 kPa) Type B acrylic4500 psi (31 027 kPa) Type C acrylicFormula:load, lb 5 w 3 t23stress in psi24load, g 5 w 3 t23stress in kPa5930wh
24、ere:w = width of specimen in inches or millimetres to nearest 0.001 in. or 0.025 mm, respectively, andt = thickness of specimen in inches or millimetres to nearest 0.001 in. or 0.025 mm, respectively. Width and thickness shall be measuredat the stress area.Note: The fulcrum radius shall be14 in. (6.
25、4 mm) where it bears on the acrylic specimen.FIG. 1 Description of Stressing ProcedureF4840828.10 After each examination at the specified intervals duringthe 8-h period, move the moist swatch back to its originalposition over the stress area and remoisten it with testcompound as required.9. Report9.
26、1 The report shall include the following:9.1.1 Test compound evaluated,9.1.2 Type of acrylic craze test specimen used,9.1.3 Description of acrylic craze test surface after test; thatis, not affected, light crazing, cracked, rippled, stained, and9.1.4 Exposure time to craze or degrade surface, whenap
27、plicable.10. Precision and Bias10.1 No statement is made about either precision or bias ofthis test method for measuring the crazing effect of thecandidate test liquid, on acrylic plastic, since the result merelystates that there is conformance to the criteria for success.Aerospace industry and mult
28、ilocation laboratory use and ac-ceptance of this test method indicates a high degree ofrepeatability.11. Keywords11.1 acrylic plastics; hairline craze crack; liquid com-pounds; outer fiber bending stress; stress crazingASTM International takes no position respecting the validity of any patent rights
29、 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 standard is subject to revision at any ti
30、me 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 International Headquarters. Your comments will
31、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.This standard is copyrighted by ASTM
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