1、Designation: D3576 15Standard Test Method forCell Size of Rigid Cellular Plastics1This standard is issued under the fixed designation D3576; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in par
2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the determination of the appar-ent cell size of rigid cellular plastics by counting the number ofcell-wall intersections in
3、 a specified distance.1.2 Procedure A requires the preparation of a thin slice, notmore than one half the average cell diameter in thickness, thatis mechanically stable. For most rigid cellular plastics thislimits the test method to materials with an average cell size ofat least 0.2 mm.1.3 Procedure
4、 B is intended for use with materials whosefriable nature makes it difficult to obtain a thin slice forviewing.1.4 The values stated in SI units are to be regarded asstandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety conce
5、rns, 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 1The annex to ISO 2896 is technically equivalent to this testmethod.2. Referen
6、ced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD2842 Test Method for Water Absorption of Rigid CellularPlasticsD6226 Test Method for Open Cell Content of Rigid CellularPlasticsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 I
7、SO Standard:ISO 2896 Cellular Plastics, RigidDetermination of WaterAbsorption33. Terminology3.1 Definitions of terms applicable to this test method aregiven in Terminology D883.4. Summary of Test Method4.1 Procedure AThe cellular plastic specimen is cut to notmore than one half the average cell diam
8、eter in thickness on aslicer and the shadowgraph is projected on a screen by the useof a cell-size scale slide assembly and a projector. The averagechord length is obtained by counting the cells on cell-wallintersections and converting this value to average cell size bymathematical derivation.4.2 Pr
9、ocedure BThe cellular plastic specimen is sliced toprovide a smooth surface. The cell walls are accented by theuse of a marking pen or marking ink. The average chord lengthis obtained by counting the cell wall intersections and convert-ing this value to average cell size by mathematical derivation.5
10、. Significance and Use5.1 Several physical properties of rigid cellular plastics aredependent on cell size and cell orientation. Measuring waterabsorption and open-cell content in accordance with TestMethod D2842 and Test Method D6226 requires knowledge ofsurface cell volume, which uses cell size va
11、lues in thecalculations.5.2 This test method provides an apparent cell size becauseit assumes that there is no measurable edge to edge or top tobottom variation in average cell size and that the cell sizedistribution about the average cell size is normal. If the analystis concerned there may be sign
12、ificant variation in either theaverage cell size or the cell size distribution more detailedanalysis may be required.5.3 Before proceeding with this test method, referenceshould be made to the specification of the material being tested.Any test specimen preparation, conditioning, dimensions, ortesti
13、ng parameters, or a combination thereof, covered in the1This test method is under the jurisdiction ofASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.22 on Cellular Materials -Plastics and Elastomers.Current edition approved Oct. 1, 2015. Published October 2015. Ori
14、ginallyapproved in 1977. Last previous edition approved in 2010 as D3576 - 04(2010).DOI: 10.1520/D3576-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standa
15、rds Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C70
16、0, West Conshohocken, PA 19428-2959. United States1materials specification shall take precedence over those men-tioned in this test method. If there are no materialspecifications, then the default conditions apply.6. Apparatus6.1 The apparatus required to perform the test as defined byProcedure A is
17、 listed as follows:6.1.1 Cell Size Specimen SlicerCutting blade apparatuscapable of slicing thin specimens (0.02 mm) for cell sizeviewing. Fig. 1 shows an acceptable alternative slicing appa-ratus.6.1.2 Cell Size ProjectorConventional 35-mm slide pro-jector that accepts standard 50 by 50-mm (2 by 2-
18、in.) slides.6.1.3 Cell Size Scale Slide Assembly, consisting of twopieces of slide glass hinged by tape along one edge, betweenwhich a calibrated scale (30 mm in length) printed on a thinplastic sheet is placed (see Fig. 2).6.2 The apparatus required to perform the test as defined byProcedure B is l
19、isted as follows:6.2.1 Cell Size Specimen SlicerCutting blade apparatuscapable of providing a smooth surface.6.2.2 Optical Magnification System, capable of 5 to 25magnification with a calibrated scale of the appropriate length.6.2.3 Highlighting Marker/Ink, that does not contain asolvent which will
20、attack the polymer system. The ink usedshould contrast with the color of the foam.7. Sampling7.1 Generally one specimen is sufficient to determine theapparent cell size of a sample.7.2 The number of samples may be dictated by the end-usedata needed.8. Procedures8.1 Procedure A:8.1.1 Cut a specimen 5
21、0 by 50 mm by thickness (2 by 2 in.by thickness) from the sample in the area to be tested.8.1.2 Prepare the cell size viewing specimen by cutting athin slice (less than monocellular) from one of the cut surfacesof the specimen. (Slice thickness should be as thin as practi-cable; so that a shadowgrap
22、h will not be occluded by overlap-ping cell walls. Optimum slice thickness will vary with theaverage cell size of the foam, with smaller cell foams requiringthinner slices.)NOTE 2One cell size measurement will provide a representativeapparent cell size for cellular plastics having symmetric cells of
23、 relativelyuniform size. However, if the cell size in the three normal directions issuspected of varying by a value greater than the precision of this testmethod, all three directions should be measured and reported for maxi-mum accuracy. An acceptable procedure, in this case, is to determine thecel
24、l size in two planes perpendicular to each other. The size of the cells inthe three normal directions can then be compared and reported separatelyif desired.8.1.3 Insert the thin-sliced foam specimen into the cell sizeslide assembly. Position the zero on the grid line at the top ofthe area to be mea
25、sured. Reassemble the slide.8.1.4 Insert the slide assembly into the projector. Focus theprojector on the wall or screen so that a sharp image shadow-graph results.FIG. 1 Razor Blade Cell Size Specimen SlicerD3576 1528.1.5 Count the number of cell walls that intersect thereference line.48.1.6 Determ
26、ine the average cell chord length, t. Divide thelength of the reference line by the number of cells counted toobtain the average chord length, t. The length of the referenceline is expressed in millimetres.8.2 Procedure B:8.2.1 Cut a 25-mm (1-in.) section across the width of thesample.8.2.2 Identify
27、 the length (L) and width (W) direction in themiddle of the strip.8.2.3 Cut a 25-mm (1-in.) section with the L and W markingfrom the center of the strip giving a specimen of 25 by 25 mmby thickness (1 by 1 in. by thickness).8.2.4 Shave adjacent planes of the sample giving exposedcut cells in the L,
28、W, and thickness (T) directions (see Note 2).8.2.5 Coat the shaved planes with the marker/ink with auniform coating in such a manner that additional cell walls arenot broken.8.2.6 Place the sample in a manner to observe cells in the Tdirection. The sample holder should be of sufficient size andinteg
29、rity so as to hold the sample steady during measurement(see Note 3).NOTE 3For samples with an apparent cell size of 0.3 mm or smallerthe cell size may be measured by the use of a scope with a 10-mmcalibrated reference line. For samples with an apparent cell size of 1.0 mmor greater a handheld eyepie
30、ce with a calibrated scale of 30-mm length canbe used.8.2.7 Count the number of cell walls which intersect thereference line.48.2.8 The cells counted must be a random selection,however, the specific placement of the line should be adjustedto start the count to include a full cell at the beginning of
31、 theline.8.2.9 Determine the average cell chord length, t. Divide thelength of the reference line by the number of cells counted toobtain the average chord length, t. The length of the referenceline is expressed in millimetres.9. Calculation9.1 Calculate the cell size for each direction measured asf
32、ollows:d 5 t1.623!where:d = cell size, mm, andt = average cell chord length, mm.See Appendix X1 for the derivation of the equation.10. Report10.1 Report the following information:10.1.1 Material type and manufacturer,10.1.2 Lot number/production date of the materialevaluated,10.1.3 Procedure used (A
33、 or B),10.1.4 The number of specimens evaluated, and10.1.5 The average cell size in millimetres for each direc-tion measured. For those foams having a cell size larger than4The reference line length should be suitable to the cell size being measured. Aminimum cell count of 20 should be adequate.FIG.
34、 2 Cell Size Scale Slide AssemblyD3576 1531.0 mm, report the value to the nearest 0.1 mm. For thosesmaller than 1.0 mm, report the value to the nearest 0.01 mm.11. Precision and Bias511.1 Tables 1 and 2 are based on a round robin conducted in1989 in accordance with Practice E691 involving six materi
35、alsfor Procedures A and B. Due to equipment limitations, onlyfour of the participants were able to obtain data with ProcedureA. All seven participants obtained data using Procedure B. Allof the samples were prepared at one source but the individualspecimens were prepared at the laboratories that tes
36、ted them.Each test result was the average of three determinations. Eachlaboratory obtained one test result for each material.WarningSections 11.2 11.2.3 are intended only to give anapproximate precision of this test method. When data isobtained from less than six laboratories, it should be viewedwit
37、h extreme caution. The data should not be rigorouslyapplied to acceptance or rejection of material. The data isspecific to the round robin and may not be representative ofother lots, conditions, materials, or laboratories. Users of thistest method should apply the principles outlined in PracticeE691
38、 to generate data specific to their laboratory and materials,or between specific laboratories.The principles of 11.2 11.2.3a would then be valid for such data.11.2 Concept of r and RIf Srand SRwere calculated froma large enough body of data, and for test results consisting ofone determination per te
39、st result:11.2.1 Repeatability Limit, r(Comparing two test resultsfor the same material, obtained by the same operator using thesame equipment on the same day.) The two test results shouldbe judged not equivalent if they differ by more than the “ r”value for that material.11.2.2 Reproducibility Limi
40、t, R(Comparing two test re-sults for the same material, obtained by different operatorsusing different equipment in different laboratories on differentdays.) The two test results should be judged not equivalent ifthey differ by more than the “R” value for that material.11.2.3 Any judgment in accorda
41、nce with 11.2.1 or 11.2.2would have an approximate 95 % (0.95) probability of beingcorrect.11.3 There are no recognized standards by which to estimatebias of this test method.12. Keywords12.1 cell size; rigid cellular plastics5Supporting data have been filed at ASTM International Headquarters and ma
42、ybe obtained by requesting Research Report RR:D20-1185.TABLE 1 Precision Data Summary, Procedure AMaterialNominalThickness, in.Average CellSize,mm% rA% RBrCRDNumber ofLaboratoriesin ResearchReportExtruded Polystyrene Foam 0.75 0.36 5.7 9.3 16.3 26.4 4Extruded Polystyrene Foam 2 0.79 7.3 12.3 20.7 34
43、.7 4Extruded Polystyrene Foam 6.5 1.6 5.3 15.1 14.9 42.8 4Polyisocyanurate Foam (Glass FibersReinforced)2 0.33 9.4 18.3 26.6 51.8 3Phenolic Foam 1 0.37 17.2 17.4 48.7 49.2 3Aris the within-laboratory coefficient of variation of the average.BRis the between-laboratories coefficient of variation of th
44、e average.Cr is the within-laboratory repeatability limit = 2.8 r.DR is the between-laboratories reproducibility limit = 2.8 R.TABLE 2 Precision Data Summary, Procedure BMaterialNominalThickness, in.Average CellSize,mm% rA% RBrCRDNumber ofLaboratories inResearch ReportExtruded Polystyrene Foam 0.75
45、0.35 8.7 11.6 24.8 32.9 6Extruded Polystyrene Foam 2 0.74 6.2 19.4 17.47 54.9 6Extruded Polystyrene Foam 6.5 1.7 5.2 15.1 14.7 42.7 5Polyisocyanurate Foam (Glass FibersReinforced)2 0.39 10.3 31.0 29.1 87.7 7Polyurethane Foam 1 0.37 10.5 32.1 29.7 90.8 6Phenolic Foam 1 0.13 8.7 14.8 24.5 41.9 3Aris t
46、he within-laboratory coefficient of variation of the average.BRis the between-laboratories coefficient of variation of the average.Cr is the within-laboratory repeatability limit = 2.8 r.DR is the between-laboratories reproducibility limit = 2.8 R.D3576 154APPENDIX(Nonmandatory Information)X1. DERIV
47、ATION OF CELL SIZEX1.1 Assumptions made in this derivation are that the cellshape is spherical and that the cells are relatively uniform withrespect to size.X1.2 Subsection 8.1.6 of this test method describes theprocedure for determining t, the average measured chordlength of the randomly truncated
48、cells. The relationship be-tween t and the average cell diameter, d, appearing at the planeof the cut surface, may be calculated as follows:X1.2.1 The mean value of the ordinates in the first quadrantfor any circle x2+ y2= r2is:y 5 1/r!*0r=r22 x2dx 5 r/4 (X1.1)where:r = radius of the cell in the sur
49、face plane, andy = t/2.Therefore:t/2 5 r/4 (X1.2)Since r = d/2 then:t 5 d/4 (X1.3)Rearrangement of Eq X1.3 yields:d 5 t/0.785 (X1.4)X1.3 The average cell diameter of the circular segments, d,is related to the diameter of the sphere, d in the same manner.The average sphere diameter is larger than the average circularsegment diameter, d, because the cells are randomly truncatedwith respect to depth at the plane of the specimen surface. Themean value of the chord length with respect to diameter (see EqX1.3) again applies:d 5 d/0.785 (X1.5)
