1、Designation: D8132/D8132M 17Standard Test Method forDetermination of Prepreg Impregnation by PermeabilityMeasurement1This standard is issued under the fixed designation D8132/D8132M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision,
2、the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method determines the in-plane permeability ofcomposite prepreg (pre-impregnated) materials as a
3、 measure oflevel of impregnation. Permissible prepreg materials includethose reinforced with carbon, glass, aramid, thermoplastic andother fibers impregnated with a thermoset or thermoplasticmatrix resin, creating a single ply sheet material.The reinforce-ments may be unidirectional or woven fabrics
4、.1.2 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith
5、 the standard.1.2.1 Within the text, the inch-pound units are shown inbrackets.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, health and environmental pra
6、ctices and deter-mine the applicability 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
7、nd Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:D883 Terminology Relating to PlasticsD3878 Terminology for Composite MaterialsE122 Practice for Calculating Sample Size to Estimate, WithSpecified Precision
8、, the Average for a Characteristic of aLot or ProcessE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE456 Terminology Relating to Quality and StatisticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitio
9、nsTerminology D3878 defines terms relatingto high-modulus fibers and their composites. TerminologyD883 defines terms relating to plastics. Terminology E456 andPractice E177 define terms relating to statistics. In the event ofa conflict between terms, Terminology D3878 shall haveprecedence over the o
10、ther terminologies.3.2 Definitions of Terms Specific to This Standard:3.2.1 as castpertaining to the transparent and smoothsurface of an acrylic block.3.2.2 acrylic block assemblythe acrylic blocks nestedtogether or clamped together but that are otherwise oriented orjoined together only for a tempor
11、ary process.3.2.3 cut sidemachined surface of an acrylic block.3.2.4 permeabilityMaterial property that determines flowthrough a porous medium. Used to determine the air transportof prepreg materials in the in-plane directions.3.2.5 permeability test apparatusthe vacuum test chamberwith known volume
12、 where the permeability test specimen ismounted and tested to determine permeability.3.2.6 permeability test specimenthe vacuum test chamberwith known volume where the permeability test specimen ismounted and tested to determine permeability.3.3 SymbolsA = cross-sectional area of the prepreg test sp
13、ecimenCV = coefficient of variation statistic of a sample populationfor a given property (in percent)FAW = fiber areal weightH = prepreg thicknessID = inner diameterK = permeabilityKn= normalized permeability (independent of prepregthickness)L = length of prepreg sampleOD = outer diameter1This test
14、method is under the jurisdiction of ASTM Committee D30 onComposite Materials and is the direct responsibility of Subcommittee D30.03 onConstituent/Precursor Properties.Current edition approved Aug. 1, 2017. Published September 2017. DOI:10.1520/D8132_D8132M-17Copyright ASTM International, 100 Barr H
15、arbor Drive, PO Box C700, West Conshohocken, 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 Recommend
16、ations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1P = absolute pressure in vacuum chamber (P as a function oftime)Patm= actual atmospheric pressurePi= initial absolute pressure in vacuum chamber (Piabsattime 0)RH = relative humiditySn-1= standard deviation st
17、atistic of a sample population fora given propertyx1= test result for an individual specimen from the samplepopulation for a given propertyx = mean or average (estimate of mean) of a samplepopulation for a given property4. Summary of Test Method4.1 This test method consists of imparting a pressure d
18、iffer-ential across a single ply of prepreg to determine the perme-ability of the material by exposing one side to the atmosphereand the other to known volume of reduced pressure. The initialreduced pressure, created by a vacuum pump, increases afterthe pump is shut off as a function of air flow thr
19、ough theprepreg. To create the test specimen, a single ply of prepreg issandwiched and bonded between acrylic blocks. This testspecimen is then attached to the surface of the known volumewith vacuum tape. This assembly provides a leak-free seal andno applied compaction pressure on the prepreg surfac
20、e duringtesting.4.2 This standard defines a test method to determine the airtransport capacity of a prepreg composite material in the planeof the fiber; in unidirectional materials, this means eitherparallel to or orthogonal to the fiber direction and in wovenfabric materials, in the warp or fill di
21、rection.4.3 A successful test is dependent on proper handling andmounting of the prepreg material sample. A leak-free seal isrequired between the prepreg and acrylic block adherends andto the surface of the test apparatus.5. Significance and Use5.1 It is well known that the prepreg impregnation leve
22、laffects handling characteristics, tack and drape, and final partquality. Resin impregnation level is the dominant factor in theability of removing air and volatiles from the layup duringprocessing. Partially impregnated prepreg materials can insome applications provide higher quality, lower void co
23、ntentcomposite parts, and are becoming increasingly more commondue to the desire to cure out-of-autoclave, using vacuumbag-only processes. This test can identify small changes in thematerial impregnation level which can assist in definition ofproduction processes or shipping and handling procedures.
24、 Thevalue of permeability can be used for specifying ranges asacceptance requirements for prepreg materials, thus enablingthe prepreg manufacturer and user greater confidence in theability to produce repeatable, high quality parts. This testdirectly determines the actual air flow propensity of thema
25、terial tested without any applied compaction pressure duringtesting.5.2 Factors that influence the permeability of the testedprepreg material shall be reported including: prepreg material,orientation, location on roll, width, length, thickness, andactual atmospheric pressure.6. Interferences6.1 Mate
26、rial and Specimen PreparationPoor material fab-rication practices, lack of control of fiber alignment, anddamage induced by improper specimen cutting are knowncauses of high data scatter in composites in general. Specificfactors that affect the prepreg test specimen permeabilityresults include compr
27、ession and bending of prepreg, handling,sharpness of cutting blades, and control of fiber alignment andorientation when cutting. Measuring prepreg thickness is verydifficult and subjective due to the viscoelastic material andnon-uniform surface and can cause significant permeabilitycalculation error
28、. When comparing values at differentlaboratories, a normalized permeability value that does not takeinto account prepreg thickness may be more applicable.6.2 Permeability Test Specimen PreparationTo maintain ahigh quality seal to the prepreg material it is important to haveclean bonding surfaces on
29、the acrylic blocks. Also theviscosity, gel, and cure time of adhesive, time to applyadhesive and mount specimen, and adhesive quantity can affectthe seal or cause undesired impregnation of areas of theprepreg. The adhesive must fill in the bond line between thetwo acrylic block adherends or there ca
30、n be a gap that isdifficult to seal from the environment. Control of the orienta-tion of the prepreg between the acrylic blocks is necessary forrepeatable results. Once the prepreg is mounted and adheredbetween the acrylic blocks, the test specimen should beallowed to cure without pressure on the pr
31、epreg. Ends of themounted prepreg should never be touched except for cuttingimmediately before testing.6.3 Mounting Blocks and AdhesiveThe mounting blocksthat are specified are based on cast clear acrylic which enablesinspection of the bond line. Other clear polymer blocks may beused but adhesion wo
32、uld need to be evaluated with themounting adhesive6.4 Mounting Permeability Test Specimen to ApparatusThe completed test specimens must be mounted with theprepreg centered so as not to touch the sides of the apparatus.An air-tight seal must be maintained throughout the testing.6.5 Barometric Pressur
33、eThe barometric pressure that isused for the calculation of permeability must be the actualbarometric pressure in the ambient testing environment and nota corrected barometric pressure. All pressure units used forcalculations must be in absolute values.6.6 GeometrySpecific geometric factors that aff
34、ect perme-ability results include prepreg thickness, width, length, andorientation.6.7 EnvironmentResults can be affected by large varia-tions in environmental conditions under which the tests areconducted. Sample preparation and testing in humidity (RH)over 70% and temperatures above 23.9 C 75 F or
35、 below15.6 C 60 F are not recommended.D8132/D8132M 1727. Apparatus7.1 Test ApparatusTest apparatus is according to drawing(Fig. 1) starting with a stainless-steel cylinder that is approxi-mately 51 mm 2.0 in. outer diameter (OD) by 115 mm4.50 in. long. One end of the cylinder is machined from thecen
36、ter resulting in a hollow right cylinder extending 69.85 mm2.75 in. from one end. Holes are bored according to drawing(Fig. 1) and tapped to attach vacuum gage and valve fitting. Amounting/base plate to support the hollow cylinder in theupright position is recommended for stability. This can bemade
37、from one of many designs and is not critical as long asit enables the top of the hollow cylinder to be upright andstable. A 6.35 mm 0.25 in. thick plate, 150 mm 6.0 in. by205 mm 8.0 in. is very effective. Two holes are bored throughthe 6.35 mm 0.25 in. plate located 50.8 mm 2.0 in. from thelong end
38、and one each at 63.5 2.5 in. from each edge. Noneof these dimensions is critical to the apparatus function. It isnecessary that the hole-size clearance is large enough toaccommodate the selected bolt. To mount the cylinder to thebase plate, two holes are drilled and tapped at the bottom of thecylind
39、er.To complete the apparatus, a digital vacuum gage with a0.25 in. MNPT is attached directly to one of the 0.25 in. FNPTtapped holes and a fitting and valve attached on the oppositeside. All threads should be sealed with anaerobic pipe threadsealant to ensure an air tight seal. The digital vacuum ga
40、geshould be capable of accuracy 60.25% full scale and display atleast 5 display digits. On the other side of the cylinder a hexnipple 0.25 in. MNPT, 25.6 mm 1.01 in. long, should beattached. To this hex nipple a valve capable of maintaining aleak free seal under vacuum is attached. A one piece stain
41、lessball valve 0.25 in., FNPT (2 ports) is recommended. The otherside of the valve can be connected to a quick disconnect ordirectly threaded into the vacuum line. A completed apparatusmounted to a baseplate is shown in Fig. 2.The total volume of the completed vacuum chamber appa-ratus from the clos
42、ed valve to the top of the open cylinderneeds to be calculated or determined from filling with appro-priate density fluid. The total volume with fittings should bebetween 85 to 90 cm35.1 to 5.5 in.3.7.2 Vacuum Pump2 to 3 CFM and capable of achievingwithin 3% of actual barometric pressure.7.3 Vacuum
43、HoseConnect to fittings/ports on vacuumpump and apparatus.7.4 Digital StopwatchAccuracy 60.01 s.7.5 Micrometers and CalipersA micrometer witha4to7 mm 0.16 to 0.28 in. nominal diameter ball interface or a flatanvil interface shall be used to measure the specimen thick-ness. A ball interface is recomm
44、ended for thickness measure-ments when at least one surface is irregular (e.g. a course peelply surface which is neither smooth nor flat). A micrometer orcaliper with a flat anvil interface shall be used for measuringlength, width, and other machined surface dimensions. The useof alternative measure
45、ment devices is permitted if specified (oragreed to) by the test requestor and reported by the testinglaboratory. The accuracy of the instrument(s) shall be suitablefor reading to within1%ofthespecimen dimensions. ForFIG. 1 Apparatus DesignD8132/D8132M 173typical specimen geometries, an instrument w
46、ith an accuracyof 60.0025 mm 60.0001 in. is adequate for thicknessmeasurements, while an instrument with an accuracy of60.025 mm 60.001 in. is adequate for measurement oflength, width, and other machined surface dimensions.7.6 BarometerCapable of reading actual barometric pres-sure with a range appr
47、opriate for elevation and resolution of0.01 in. Hg 1 mbar.7.7 Acrylic BlocksBlocks of cast acrylic with dimensionsapproximately 24 mm 24 mm 76.2 mm 0.944 in. 0.944in. 3 in. for mounting prepreg. These can be cut from oneinch thick cast acrylic sheet. Note one inch cast acrylic sheet isreally 0.944 i
48、n. thick.7.8 AdhesiveTwo part, 5 min cure epoxy. Used to adherethe prepreg to the acrylic blocks.7.9 Sealant TapeSealant tape used for vacuum bag devel-opment for composite processing. Use to attach the acrylicblock prepreg assembly sample to the open top rim of theapparatus cylinder.8. Sampling and
49、 Test Specimens8.1 SamplingThe number of tests and location of speci-mens is determined by the test requestor. If not specified, atleast five specimens should be tested unless valid results can begained through the use of fewer specimens, as in the case of adesigned experiment. For a roll of prepreg, often both edgesand middle require testing but may also include beginning andend of rolls. For statistically significant data, consult theprocedures outlined in Practice E122. Report the method ofsampling.8.2 Geometr
