1、Designation: D 6226 05Standard Test Method forOpen Cell Content of Rigid Cellular Plastics1This standard is issued under the fixed designation D 6226; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A num
2、ber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers cellular plastics, which arecomposed of membranes or walls of polymer separating smallcavities or cells. These c
3、ells may be interconnecting (opencell), non-connecting (closed cell), or any combination of thesetypes. This test method determines numerical values for opencells. It is a porosity determination, measuring the accessiblecellular volume of a material. The remaining volume is thatoccupied by closed ce
4、lls and cell walls. Since any convenientlysized specimen can only be obtained by some cutting opera-tion, a fraction of the closed cells will be opened by specimenpreparation and will be included as open cells, (see Note 2).1.2 This test method provides good accuracy on predomi-nantly highly open-ce
5、lled materials. By not accounting forclosed cells that were opened during specimen preparation, theaccuracy decreases as the closed cell content increases and asthe cell size increases.1.3 The values as stated in SI units are to be regarded as thestandard. The values in brackets are given for refere
6、nce only.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.NOTE 1
7、This test method and ISO 4590-1981 use the same basicprinciples but are significantly different in experimental detail.NOTE 2Two procedures for correcting for cells opened during speci-men preparation are described in Appendix X1.1.2. Referenced Documents2.1 ASTM Standards:2D 883 Terminology Related
8、 to PlasticsD 2842 Test Method for Water Absorption of Rigid CellularPlasticsD 3576 Test Method for Cell Size of Rigid Cellular PlasticsE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 4590-1981 Cellular PlasticsDetermination of Vo
9、l-ume Percentage of Open and Closed Cells of RigidMaterials33. Terminology3.1 Definitions:3.1.1 Terms relating to plastics as given in TerminologyD 883 shall be used where applicable.3.2 Definitions of Terms Specific to This Standard:3.2.1 closed cella cell totally enclosed by its walls andhence not
10、 interconnecting with other cells.3.2.2 open cella cell not totally enclosed by its walls andopen to the surface either directly or by interconnecting withother cells.3.2.3 volume of closed cells and cell wallsinaccessibleinternal volume, consisting of an aggregate of solid polymervolume (cell walls
11、, struts), filler volume, when applicable(solid particles or fibers), the volume of individual closed cells,and the volume of small cell groups interconnected by rupturedcell walls but otherwise inaccessible.3.2.4 uncorrected volume of open cellsthe aggregate mea-surement of both the internal porous
12、 volume of the materialand the various irregular volumes accessible at the cut-cellsurface of the test specimen.3.3 Symbols:3.3.1 dspecimen diameter, cm.3.3.2 hspecimen height, cm.3.3.3 lspecimen length, cm.3.3.4 Ovvolume, percent open cells.3.3.5 Vgeometric volume of specimen, cm3.3.3.6 VCALIBvolum
13、e of the calibration standard, cm3.3.3.7 VCHAMBERvolume of the sample chamber, cm3.3.3.8 VEXPexpansion reference volume, cm3.3.3.9 VSPECspecimen displacement volume, cm3, and,3.3.10 wspecimen width, cm.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct res
14、ponsibility of Subcommittee D20.22 on Cellular MaterialsPlastics and Elastomers.Current edition approved April 1, 2005. Published June 2005. Originallyapproved in 1998. Last previous edition approved in 1998 as D 6226 - 98e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
15、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*A Summary of Changes sectio
16、n appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Summary of Test Method4.1 This test method is based on a determination of porosityin which the accessible cellular volume of a cellular plastic i
17、sdetermined by application of Boyles Law, which states thatthe increase in volume of a confined gas results in a propor-tionate decrease in pressure. The apparatus consists of twochambers of known volume connected by a valve. One of thechambers, the calibrated sample chamber, is accessible forinsert
18、ion of the test specimen and is connected to a source ofhigh purity (at least 99.99 %) dry gas, such as nitrogen orhelium. The pressure in the sample chamber is increased to apredetermined pressure and this value, P1, is noted. The valvebetween the two chambers is then opened and the second,lower Pr
19、essure, P2, is again noted. The ratio of the pressurechange P1/P2, is directly related to the volume of the samplechamber displaced by the specimen. The difference betweenthis volume and the geometric volume of the specimen is ameasure of the open-cell volume.NOTE 3The criteria for selecting a dry g
20、as are that the gas shall notexhibit significant non-ideal behavior, dissolve the matrix, or readilydiffuse into the matrix.5. Significance and Use5.1 This test method is intended to be used in specificationswhere porosity of cellular plastics has a direct bearing on theirend use. For example, for t
21、hermal insulation applications, ahigh percentage of closed cells is necessary to prevent escapeof gases and to promote low thermal conductivity. In flotationapplications, high closed-cell content generally reduces waterabsorption.5.2 Before proceeding with this test method, reference shallbe made to
22、 the specification of the material being tested. Anytest specimen preparation, conditioning, or dimensions, orboth, and testing parameters covered in the materials specifi-cation shall take precedence over those mentioned in this testmethod. If there are no material specifications, then the defaultc
23、onditions apply.6. Apparatus6.1 Gas PycnometerA schematic diagram of the pycnom-eter apparatus is shown in Fig. 1. It shall have the followingfeatures:6.1.1 Sample Chamber (VCHAMBER), having a volume ap-proximately between 30 and 150 cm31.8 and 9.2 in.3,calibrated to the nearest 0.1 cm30.006 in.3.6.
24、1.2 Expansion Reference Volume (VEXP), a precisely cali-brated volume known to the nearest 0.1 cm30.006 in.3.6.1.3 Gage Pressure Transducer, capable of measuring 0 to175 kPa 0 to 25 psig with minimum volume displacement andlinear within 0.1%.6.1.4 Pressure Relief Valve, to avoid over pressurization
25、ofthe transducer.6.1.5 Filter, to prevent powder from contaminating thetransducer and selector valves.6.1.6 Input Flow Control Toggle and Needle Valves,oralternative means to control pressurization.6.1.7 Output Flow Control Toggle and Needle Valves,oralternative means to vent the gas.6.1.8 Two-Way S
26、elector Valve, to connect the referencevolume to the sample chamber.6.1.9 Nonporous Calibration Standard, (for example, astainless steel sphere) of known volume which fills from13 to23 of the sample chamber.6.1.10 Digital Meter, for reading the pressure from thetransducer to 0.007 kPa 0.001 psig.6.1
27、.11 Sample Chamber Closure, with O-ring seal.6.1.12 Calibration Procedure, for the gas pycnometer isoutlined in A2.26.2 Cutting Device, for specimen preparation, such as abandsaw or hobby jigsaw, the blade of which must be capableof producing a smooth cut. This will require a blade with atleast 4 te
28、eth/cm 10 teeth/in. A cellular hole cutter can also beused.6.3 Vernier Calipers, or micrometer measuring device, ca-pable of measuring specimens to the nearest 0.003 cm 0.001in.7. Sampling and Test Specimen Preparation7.1 The standard test specimen is two cubes having anominal dimension of 2.5 by 2.
29、5 by 2.5 cm 1.0 by 1.0 by 1.0in., (see Note 4). An alternative configuration is two cylinderswith nominal cross sectional areas of 6.25 cm20.97 in. by 2.5cm 1.0 in. in height, (see Note 5). It is possible that it will bepractical in some instances (for example, when using smaller-sized sample chambe
30、rs or when there is a limited amount ofmaterial) to use only one cube or one cylinder. However, thespecimen displacement volume (VSPEC) shall be at least 15 %of the sample chamber volume.NOTE 4The analyst shall not substitute a single 5 by 2.5 by 2.5 cmrectangular prism for the two cubes because the
31、 surface areas are notequal.NOTE 5The cylindrical configuration is not recommended for aniso-tropic materials.7.2 Unless otherwise agreed upon, at least three sets of twocubes or two cylinders, selected at random, shall be tested. Allspecimens having obvious defects shall be omitted.7.3 Sample selec
32、tion on commercially available materialsshall be by agreement between the supplier and the user.7.4 Test specimens shall be machined or sawed from thesample so as to have smooth surfaces. It is permissible formachined or sawed surfaces to be further smoothed by slicingtechniques or sanding with a nu
33、mber 400 or finer sandpaper.Resulting dust shall be blown from the specimens.FIG. 1 Schematic Diagram of Gas PycnometerD62260528. Conditioning8.1 Condition specimens at standard laboratory atmosphere23 6 2C 73.4 6 3.6F and 50 6 5 % relative humidity fora minimum of 24 h.8.2 Since this test method de
34、pends on very accurate mea-surement of gas pressures, the temperature of the environment,the apparatus, the specimen, and the sample cup must be keptconstant within 62C.8.3 The temperature at which the calibration is performedshall be within 62C of the temperature at which the analysisis performed.9
35、. Procedure9.1 Measure and record the length, l, height, h, and width,w, of the specimens to the nearest 0.003 cm 0.001 in. If usingcylindrical specimens measure the height, h, and diameter, d.9.2 Close the flow valve if not already closed.9.3 Operate the two-way selector valve so that it isolates t
36、heexpansion volume (reference) chamber from the rest of thesystem.9.4 Open the vent valve if not already open.9.5 Remove the sample chamber cap if not already open andremove any previous specimen.9.6 Insert the new specimen and securely replace the samplechamber cap.9.7 Air, and vapors trapped withi
37、n pores, crevices, or amongthe pieces of the specimen will be removed from the specimenby a prolonged purge when all valves are opened. Report thetime used. However, these impurity gases are much morerapidly removed by alternately increasing and decreasing thegas pressure in the sample chamber.9.8 C
38、lose the vent valve and open the flow valve. Allow thepressure to rise to 20 kPa 2.9 psig, then close the flow valveand open the vent valve. When the pressure has fallen to lessthan 3 kPa 0.4 psig, close the vent valve. This purgingprocess shall be repeated at least twice more. The vent valvemust re
39、main open at the completion of the purge process.Report the number of purge cycles used.9.9 Operate the two-way selector valve so that it connectsthe expansion volume (reference) chamber with the rest of thesystem. Allow the pressure to fall to a steady value, correctingthe pressure display with the
40、 zero control as necessary.9.10 Operate the two-way selector valve so that it againisolates the expansion volume (reference) chamber from therest of the system, ensuring that the pressure display does notshift from zero. If a shift occurs, repeat 9.9.9.11 Close the vent valve neglecting any change i
41、n pressure.9.12 Open the flow valve and fill the chamber to 20 kPa 2.9psig as shown on the pressure indicator.NOTE 6It will be desirable in some instances to use pressures lessthan 20 kPa for the purging and testing steps. The applied pressure shallnot distort the specimen. If other pressures are us
42、ed, they shall be noted onthe test report.9.13 Close the flow valve and allow the pressure to stabilizeor wait a fixed period of time (10 to 15 s give best results formost samples) and record the final pressure as P1. Report thetime used if the pressure did not stabilize.9.14 Immediately operate the
43、 two-way selector valve so thatit again connects the expansion volume (reference) chamberwith the rest of the system and allow the pressure to stabilizeor wait the same fixed period of time as in 9.13. Record thefinal pressure as P2.NOTE 7If the pressure reading drifts continuously to lower pressure
44、s,the cells may be rupturing or the test gas may be diffusing through the cellwalls. Under these conditions, an accurate open-cell content cannot bedetermined.9.15 Open the vent valve and allow the pressure to fall to 0kPa 0 psig.9.16 Return to 9.9 if multiple determinations are to be madeon this sp
45、ecimen.9.17 Remove the specimen from the sample chamber.9.18 If the instrument is to remain idle for an extendedperiod (days), close the sample chamber and shut off the gassupply.9.19 Calculate the specimen volume from the general equa-tion:VSPEC5 VCHAMBERVEXP/P1/P2! 1. (1)NOTE 8Several companies pr
46、oduce both manually operated andautomatically operated gas pycnometers which meet the specificationsdescribed herein. Please refer to the specific operating manuals foradditional details on operation and calibration.10. Calculation10.1 Calculate the geometric volume, V, in cubic centime-tres of the
47、specimen by adding together the volumes of itscomponent specimens determined from their measurements oflength, width, and height as follows:If two cubes: V 5 l13 w13 h1! 1 l23 w23 h2! (2)Or if two cylinders: V 5 p3d123 h1!/4 1 p3d223 h2!/4.(3)10.2 Calculate the open-cell content, Os, of each specime
48、nexpressed as the percentage of the calculated volume, V,asfollows:OV5 V VSPEC!/V 3 100 (4)10.3 If desired the percent volume occupied by the closedcells and cell walls, CWV, can be calculated from the equation:CWV5 100 OV(5)10.4 When the specific gravity of the material in its solidform is known th
49、e percent volumes occupied by the cell walls,WV, and the closed cells, CV, can be calculated individually.The cell wall volume percentage is calculated as follows:WV5 m / sg 3 V!# 3 100 (6)where:m = the mass of the specimen, g,sg = the specific gravity of the material in solid form,g/cm3, andV = the geometric volume of the specimen, cm3.10.5 The closed cell volume percentage can be then calcu-lated with the equation:CV5 100 OV WV(7)D622605311. Report11.1 Report the following information:11.1.1
