1、Designation: C 272 01 (Reapproved 2007)Standard Test Method forWater Absorption of Core Materials for Structural SandwichConstructions1This standard is issued under the fixed designation C 272; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, 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 met
3、hod covers the determination of the relativeamount of water absorption by various types of structural corematerials when immersed or in a high relative humidityenvironment. This test method is intended to apply to onlystructural core materials; honeycomb, foam, and balsa wood.1.2 The values stated i
4、n SI units are to be regarded as thestandard. The inch-pound units given may be approximate.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 pract
5、ices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C 271/C 271M Test Method for Density of Sandwich CoreMaterialsC 274 Terminology of Structural Sandwich ConstructionsD 1193 Specification for Reagent Water3. Terminology3.1 Definiti
6、onsTerminology C 274 defines terms relatingto sandwich constructions.4. Summary of Test Method4.1 A small piece of the core material is conditioned invarious moisture conditions, and the amount of moistureabsorbed is measured by the weight increase in the specimen.5. Significance and Use5.1 The mois
7、ture content of most core materials is related tosuch properties as electrical properties (such as dielectricconstant, loss tangent, and electrical resistance) and mechani-cal properties (such as strength and modulus). The amount ofweight the structure may gain by the core absorbing water isalso imp
8、ortant. It should be noted that in a sandwich panelthere are facings bonded on two sides of the core that affect theamount of water absorbed by the core.6. Interferences6.1 Material and Specimen PreparationCracks in thespecimen and rough surfaces can increase the apparent waterabsorption.6.2 Surface
9、 WaterSome core materials tend to collectwater on the surfaces or trap water in corners, and, if notremoved will give incorrect results.7. Apparatus7.1 Analytical Balance, capable of measurement to 0.001 g.7.2 Circulating Air Oven, capable of maintaining uniformtemperatures with an accuracy of 63C (
10、65F).7.3 Humidity Chamber, capable of maintaining uniformrelative humidity with an accuracy of 65 % and a uniformtemperature with an accuracy of 63C (65F).7.4 The water used in this test method shall be distilledwater (Specification D 1193, Type IV reagent water) or deion-ized water.8. Sampling and
11、Test Specimens8.1 Test at least five specimens per test condition unlessvalid results can be gained through the use of fewer specimens,such as in the case of a designed experiment.8.2 The test specimen shall be 75 by 75 by 12.7 mm (3 by3 by 0.5 in.) thick. The thickness of the specimen shall be in t
12、hesame direction as the core thickness when used in a sandwichpanel.8.3 Machine, saw, or shear the test specimens from the coresample so as to have smooth surfaces that are free from cracks.1This test method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct resp
13、onsibility of Subcommittee D30.09 onSandwich Construction.Current edition approved Jan. 1, 2007. Published January 2007. Originallyapproved in 1951. Last previous edition approved in 2001 as C 272 01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Servic
14、e at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8.4 Measure the length and width dimensions to
15、 the nearest0.25 mm (0.01 in.) and the thickness to the nearest 0.025 mm(0.001 in.).9. Calibration9.1 The accuracy of all measuring equipment shall havecertified calibrations that are current at the time of use of theequipment.10. Conditioning10.1 Weigh the specimens individually and then oven dry a
16、sfollows:10.1.1 For materials whose water absorption value would beaffected by temperatures up to approximately 110C (230F),dry the specimens in an oven for 24 h at 50 6 3C (120 65F), cool in a desiccator to room temperature, remove, andimmediately weigh and record the weight.10.1.2 For materials wh
17、ose water absorption value has beenshown not to be affected by temperatures up to 110C (230F),dry the specimens in an oven for2hat1056 3C (225 6 5F),cool in a desiccator to room temperature, remove, and imme-diately weigh and record the weight.10.1.3 In the case of a new material of which the watera
18、bsorption properties are not known, condition the specimensin accordance with 10.1.1 and 10.1.2 until sufficient experienceon the effect of temperature is achieved to indicate the selectionof the most satisfactory method.11. Procedure11.1 Test Method ATwenty-Four-Hour ImmersionCompletely immerse the
19、 specimens in a container of 23 6 3C(73 6 5F) water. Materials that float should be held underwater by a loose net.At the end of 24 h, remove the specimens,shake vigorously, wipe off all surface water with a dry cloth,and immediately weigh and record the weight. For materialsthat tend to collect wat
20、er on the surfaces or trap water incorners, dip the specimen in alcohol, shake vigorously, allowthe alcohol to evaporate, and immediately weigh and record theweight.11.2 Test Method BElevated Temperature Humidity:11.2.1 The standard condition shall be 70 6 3C (160 65F) and 85 6 5 % relative humidity
21、 for 30 days. However,other temperatures, relative humidities, and lengths of time canbe used but must be reported.11.2.2 Place the specimens in the chamber with the 75 by 75mm (3 by 3 in.) planes in the vertical position and the endssitting on an open base (such as a screen or perforatedmaterial).1
22、1.2.3 The standard conditioned specimens should not havecondensed water on their surfaces. Therefore, take the speci-mens out of the chamber, allow to cool to room temperature,and immediately weigh and record the weight.11.2.4 For specimens in conditions that cause condensationwater to be on the spe
23、cimens surfaces, remove the specimensfrom the chamber, shake vigorously, wipe off all surface waterwith a dry cloth (if required), dip the specimen in alcohol,shake vigorously, allow the alcohol to evaporate, and immedi-ately weigh and record the weight.11.3 Test Method CMaximum Percent Weight GainC
24、ompletely immerse the specimens in a container of water ata temperature of 23 6 3C (73 6 5F). Materials that floatshould be held under water by a loose net. At the end of 48 h,remove the specimens one at a time, shake vigorously, wipe offall surface water with a dry cloth (if required), dip thespeci
25、mens in alcohol, shake vigorously, allow the alcohol toevaporate, and immediately weigh, and record the weight.Place the specimens back into the water and repeat this processuntil the weight gain after one 48-h interval is less than 2 % ofthe entire weight gain of all the previous intervals.11.4 Sur
26、face Water CorrectionWhen surface water on thespecimens presents a problem, determine the amount of surfacewater left on the specimens using the following procedure.Weigh five control samples, dip quickly in water, then followthe same procedure used on the actual specimens to determinethe weight gai
27、n. Subtract the average surface water weight gainto correct the actual wet specimen weight.12. Calculation12.1 Calculate the percentage increase in weight as follows:Increase in weight, % 5W 2 DD3 100 (1)where:W = wet weight, andD = dry weight.12.2 Calculate the specimen density in accordance with T
28、estMethod C 271.13. Report13.1 Report the following information:13.2 Description of core material tested,13.3 Product designation and batch number,13.4 Method and conditions of test environment used,13.5 Individual specimen dimensions, weight, and densitybefore conditioning,13.6 Individual specimen
29、weight increase percentage (noteif corrected for surface water), and13.7 Average, standard deviation, and coefficient of varia-tion of the weight increase percentage.14. Precision and Bias14.1 PrecisionThe data required for the development of aprecision statement is not available for this test metho
30、d.14.2 BiasBias cannot be determined for this test methodas no accepted reference standard exists.15. Keywords15.1 moisture content; water absorption; water saturationC 272 01 (2007)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any ite
31、m 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 time by the responsible technical comm
32、ittee 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 receive careful consideration at a m
33、eeting 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 International, 100 Barr Harbor Drive
34、, 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).C 272 01 (2007)3
