1、Designation:C27201(Reapproved2007) Designation: C272/C272M 12Standard Test Method forWater Absorption of Core Materials for Structural SandwichConstructions1This standard is issued under the fixed designation C272/C272M; the number immediately following the designation indicates the yearof original
2、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.This standard has been approved for use by agencies of the Department of Defense
3、.1. Scope1.1This test method covers the determination of the relative amount of water absorption by various types of structural corematerials when immersed or in a high relative humidity environment. This test method is intended to apply to only structural corematerials; honeycomb, foam, and balsa w
4、ood.1.2The values stated in SI units are to be regarded as the standard. The inch-pound units given may be approximate.1.1 This test method covers the determination of the relative amount of water absorption by various types of sandwichconstruction core materials when immersed in water, or when subj
5、ected to a high relative humidity environment. Permissible corematerial forms include those with continuous bonding surfaces (such as balsa wood and foams) as well as those with discontinuousbonding surfaces (such as honeycomb).1.2 The values stated in either SI units or inch-pound units are to be r
6、egarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformance with the standard.1.2.1 Within the text the inch-pound units are shown in
7、brackets.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Refer
8、enced Documents2.1 ASTM Standards:C271/C271MTest Method for Density of Sandwich Core Materials ASTM Standards:2C274 Terminology of Structural Sandwich ConstructionsD883 Terminology Relating to PlasticsD1193 Specification for Reagent Water Specification for Reagent WaterD3878 Terminology for Composit
9、e MaterialsD5229/D5229M Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix CompositeMaterialsE122 Practice for Calculating Sample Size to Estimate, With Specified Precision, the Average for a Characteristic of a Lot orProcessE177 Practice for Use of the Ter
10、ms Precision and Bias in ASTM Test MethodsE456 Terminology Relating to Quality and Statistics3. Terminology3.1 DefinitionsTerminology Terminology D3878 defines terms relating to high-modulus fibers and their composites.Terminology C274 defines terms relating to sandwich constructions. defines terms
11、relating to structural sandwich constructions.Terminology D883 defines terms relating to plastics. Terminology E456 and Practice E177 define terms relating to statistics. Inthe event of a conflict between terms, Terminology D3878 shall have precedence over the other terminologies.1This test method i
12、s under the jurisdiction of ASTM Committee D30 on Composite Materials and is the direct responsibility of Subcommittee D30.09 on SandwichConstruction.Current edition approved Jan. 1, 2007. Published January 2007. Originally approved in 1951. Last previous edition approved in 2001 as C27201. DOI:10.1
13、520/C0272-01R07.Current edition approved April 1, 2012. Published May 2012. Originally approved in 1951. Last previous edition approved in 2007 as C272 01 (2007). DOI:10.1520/C0272_C0272M-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at ser
14、viceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version
15、. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International,
16、 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2 Symbols:3.2.1 CVcoefficient of variation statistic of a sample population for a given property (in percent).3.2.2 Dpre-immersion mass of a test specimen.3.2.3 hheight of a test specimen.3.2.4 llength of a test s
17、pecimen.3.2.5 Sn1standard deviation statistic of a sample population for a given property.3.2.6 x1test result for an individual specimen from the sample population for a given property.3.2.7 xmean or average (estimate of mean) of a sample population for a given property.3.2.8 Vvolume of a test speci
18、men.3.2.9 wwidth of a test specimen.3.2.10 Wmass of a test specimen.4. Summary of Test Method4.1A small piece of the core material is conditioned in various moisture conditions, and the amount of moisture absorbed ismeasured by the weight increase in the specimen.4.1 This test method consists of exp
19、osing sandwich core specimen to a defined moisture condition, and determining the amountof water absorbed by measuring the mass increase in the specimen.5. Significance and Use5.1The moisture content of most core materials is related to such properties as electrical properties (such as dielectric co
20、nstant,loss tangent, and electrical resistance) and mechanical properties (such as strength and modulus). The amount of weight thestructure may gain by the core absorbing water is also important. It should be noted that in a sandwich panel there are facingsbonded on two sides of the core that affect
21、 the amount of water absorbed by the core.5.1 Absorbed water affects the characteristic properties of sandwich core materials, such as electrical properties (for example,dielectric constant, loss tangent, and electrical resistance) and mechanical properties (for example, strength and modulus). Thema
22、ss of absorbed water may also affect the behavior of sandwich structures. It should be noted that in a sandwich panel thepresence of facings bonded on two sides of the core may affect the amount of water absorbed by the core.5.2 This test method provides a standard method of obtaining sandwich core
23、moisture absorption data for design properties,material specifications, research and development applications, and quality assurance.5.3 Factors that influence the water absorption and shall therefore be reported include the following: core material, methods ofmaterial fabrication, core geometry (ho
24、neycomb cell size, honeycomb cell wall thickness, foam pore size, etc.), specimengeometry, specimen preparation, methods of mass and dimensional measurement, specimen conditioning, and moisture contentduring mass and dimensional measurements.6. Interferences6.1 Material and Specimen PreparationCrack
25、s in the specimen and rough surfaces can increase the apparent waterabsorption. Poor material fabrication practices and damage induced by improper specimen machining are known causes of highdata scatter in composites and sandwich structures in general. Important aspects of sandwich core specimen pre
26、paration thatcontribute to data scatter include the existence of joints, voids or other core discontinuities, out-of-plane curvature, and surfaceroughness. Cracks in the specimen and rough surfaces can increase the apparent water absorption.6.2 Surface WaterSome core materials tend to collect water
27、on the surfaces or trap water in corners, and, if not removed willgive incorrect results.6.3 EnvironmentResults are affected by the environmental conditions under which specimens are conditioned.7. Apparatus7.1 Analytical Balance, capable of measurement to 0.001 g. Analytical Balance or Weighing Sca
28、leAn analytical balance orweighing scale is required that is capable of measuring accurately to 0.001 g.7.2 Oven:7.2.1 Circulating Air Oven, capable of maintaining uniform temperatures with an accuracy of 63C (65F). For ProcedureA and C tests, an air-circulating oven is required that shall be capabl
29、e of maintaining the required uniform temperatures to within63C 65F.7.2.2 Circulating Air Vacuum OvenFor Procedure B tests, an air-circulating oven is required that shall be capable ofmaintaining the required uniform temperatures to within 63C 65F, shall be capable of achieving full vacuum, and shal
30、l havea drying device on the air inlet line.7.3 DesiccatorA clean, dry desiccator is required; specimens being oven-dried shall be brought to laboratory temperaturefollowing removal from the oven.7.4 Humidity Chamber, A humidity chamber is required that shall be capable of maintaining uniform relati
31、ve humidity withan accuracy of 65 % and a uniform temperature with an accuracy of 63C (65F).65F.7.4The7.5 The water used in this test method shall be distilled water (Specification D1193, Type IV reagent water) or deionizedwater.C272/C272M 1228. Sampling and Test Specimens8.1Test at least five speci
32、mens per test condition unless valid results can be gained through the use of fewer specimens, suchas in the case of a designed experiment.8.2The test specimen shall be 75 by 75 by 12.7 mm (3 by 3 by 0.5 in.) thick. The thickness of the specimen shall be in the samedirection as the core thickness wh
33、en used in a sandwich panel.8.3Machine, saw, or shear the test specimens from the core sample so as to have smooth surfaces that are free from cracks.8.4Measure the length and width dimensions to the nearest 0.25 mm (0.01 in.) and the thickness to the nearest 0.025 mm (0.001in.).8.1 Test at least fi
34、ve specimens per test condition unless valid results can be gained through the use of fewer specimens, suchas in the case of a designed experiment. For statistically significant data, consult the procedures outlined in Practice E122. Reportthe method of sampling.8.2 GeometryTest specimens shall have
35、 a square or rectangular cross-section. The recommended specimen size is 75 mm 3.0in. in length by 75 mm 3.0 in. in width by 13 mm 0.5 in. in thickness.NOTE 1The specimens cross-sectional area (length times width) is defined in the facing plane, in regard to the orientation that the core would bepla
36、ced in a structural sandwich construction. For example, for a honeycomb core the cross-sectional area is defined in the plane of the cells, which isperpendicular to the orientation of the cell walls.8.3 Specimen Preparation and MachiningMachine, saw, or shear the test specimens from the core sample
37、so as to havesmooth surfaces that are free from cracks and facing plane surfaces that are parallel to each other and perpendicular to the sidesof the specimen. Record and report the specimen cutting preparation method.8.4 LabelingLabel the test specimens so that they will be distinct from each other
38、 and traceable back to the sheet of origin,and will neither influence the test nor be affected by it.9. Calibration9.1 The accuracy of all measuring equipment shall have certified calibrations that are current at the time of use of the equipment.10. Conditioning10.1Weigh the specimens individually a
39、nd then oven dry as follows: Pre-Test Conditioning10.1 Oven dry the specimens as follows:10.1.1 For materials whose water absorption value would be affected by temperatures up to approximately 110C (230F), drythe specimens in an oven for 24 h at 50 6 3C (120 6 5F), cool in a desiccator to room tempe
40、rature, remove, and immediatelyweigh and record the weight.10.1.2For materials whose water absorption value has been shown not to be affected by temperatures up to 110C (230F), drythe specimens in an oven for2hat1056 3C (225 6 5F), cool in a desiccator to room temperature, remove, and immediatelywei
41、gh and record the weight.10.1.3In the case of a new material of which the water absorption properties are not known, condition the specimens inaccordance with 10.1.1 and 10.1.2 until sufficient experience on the effect of temperature is achieved to indicate the selection ofthe most satisfactory meth
42、od. For materials whose water absorption value would be affected by temperatures up to approximately110C 230F, dry the specimens in an oven for 24 h at 50 6 3C 120 6 5F, cool in a desiccator to room temperature, remove,and immediately weigh and record the mass. After weighing, immediately place the
43、specimens in the water or humidity chamber.10.1.2 For materials whose water absorption value has been shown not to be affected by temperatures up to 110C 230F, drythe specimens in an oven for2hat1056 3C 225 6 5F, cool in a desiccator to room temperature, remove, and immediatelyweigh and record the m
44、ass. After weighing, immediately place the specimens in the water or humidity chamber.10.1.3 For specimens to be conditioned using Procedure B below, dry the specimens per 10.1.1 or 10.1.2 in a vacuum dryingoven without application of vacuum. After the time periods specified above, apply full vacuum
45、 for 30 min to remove remainingtraces of moisture. When reducing the vacuum level, ambient venting air should be passed through a calcium sulfate desiccant orsuitable alternate in-line trap.10.2 In the case of a new material of which the water absorption properties are not known, conditioning separa
46、te specimens inaccordance with 10.1.1 and 10.1.2, followed by the specified procedure below is recommended until sufficient experience on theeffect of temperature is achieved to indicate the selection of the most satisfactory method.11. Procedure11.1 Test Method ATwenty-Four-Hour ImmersionCompletely
47、 immerse the specimens in a container of 23 6 3C (73 65F) water. Materials that float should be held under water by a loose net. At the end of 24 h, remove the specimens, shakevigorously, wipe off all surface water with a dry cloth, and immediately weigh and record the weight. For materials that ten
48、d tocollect water on the surfaces or trap water in corners, dip the specimen in alcohol, shake vigorously, allow the alcohol to evaporate,and immediately weigh and record the weight. Parameters to Be Specified Before Test:11.1.1 The specimen sampling method and specimen geometry.11.1.2 The propertie
49、s and data reporting format desired.C272/C272M 123NOTE 2Determine specific material property, accuracy, and data reporting requirements prior to test for proper selection of apparatus.11.1.3 The pre-test conditioning method and parameters.11.1.4 The balance or weighing scale measurement accuracy.11.1.5 The conditioning procedure (A, B or C) to be used.11.2 Test Method BElevated Temperature HumidityGeneral Instructions:11.2.1The standard condition shall be 70 6 3C (160 6 5F) and 85 6 5% relative humi
