1、Designation: D1505 10D1505 18Standard Test Method forDensity of Plastics by the Density-Gradient Technique1This standard is issued under the fixed designation D1505; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This test method covers the determin
3、ation of the density of solid plastics.1.2 This test method is based on observing the level to which a test specimen sinks in a liquid column exhibiting a densitygradient, in comparison with standards of known density.NOTE 1This test method is equivalent to ISO 1183-2.1.3 The values stated in SI uni
4、ts are to be regarded as the standard.1.4 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 safety, health, and healthenvironmental practices and determine theapp
5、licability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the
6、 World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD2839 Practice for Use of a Melt Index Strand for Determining Density of PolyethyleneD4703 Practice for Compression Molding Thermoplastic Materials in
7、to Test Specimens, Plaques, or SheetsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test MethodE2935 Practice for Conducting Equivalence Testing in Laboratory Applications2.2 ISO Standard:ISO 1183-2 Methods for Determining the Density and Relative Density of No
8、ncellular Plastics33. Terminology3.1 Refer to Terminology D883 for definitions of other terms relating to this test method.3.2 Definitions:3.2.1 density of plasticsthe weight per unit volume of material at 23C, expressed as follows:D23C,g/cm3 (1)NOTE 2Density is to be distinguished from specific gra
9、vity, which is the ratio of the weight of a given volume of the material to that of an equalvolume of water at a stated temperature.4. Significance and Use4.1 The density of a solid is a conveniently measurable property which is frequently useful as a means of following physicalchanges in a sample,
10、as an indication of uniformity among samples, and a means of identification.1 This test method is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.70 on Analytical Methods (SectionD20.70.01).Current edition approved July 1, 2010April 1, 20
11、18. Published September 2010April 2018. Originally approved in 1957. Last previous edition approved in 20032010 asD1505 - 03.D1505 - 10. DOI: 10.1520/D1505-10.10.1520/D1505-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For
12、Annual Book ofASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http:/www.ansi.org.This document is not an ASTM standard and is intended only
13、 to provide the user of an ASTM standard an indication of what changes have been made to the previous version. 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 versio
14、nof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 This test method is designed to yield
15、 results accurate to better than 0.05 %.NOTE 3Where accuracy of 0.05 % or better is desired, the gradient tube shall be constructed so that vertical distances of 1 mm shall represent densitydifferences no greater than 0.0001 g/cm.3 The sensitivity of the column is then 0.0001 g/cm3mm. Where less acc
16、uracy is needed, the gradient tube shallbe constructed to any required sensitivity.5. Apparatus5.1 Density-Gradient TubeA suitable graduate with ground-glass stopper.45.2 Constant-Temperature BathAmeans of controlling the temperature of the liquid in the tube at 2360.1C.Athermostattedwater jacket ar
17、ound the tube is a satisfactory and convenient method of achieving this.5.3 Glass FloatsA number of calibrated glass floats covering the density range to be studied and approximately evenlydistributed throughout this range.5.4 Pycnometer, for use in determining the densities of the standard floats.5
18、.5 Liquids, suitable for the preparation of a density gradient (Table 1).NOTE 4It is very important that none of the liquids used in the tube exert a solvent or chemical effect upon the test specimens during the time ofspecimen immersion.5.6 HydrometersA set of suitable hydrometers covering the rang
19、e of densities to be measured. These hydrometers shall have0.001 density graduations.5.7 Analytical Balance, with a sensitivity of 0.0001 g or better.5.8 Siphon or Pipet Arrangement, for filling the gradient tube. This piece of equipment shall be constructed so that the rate offlow of liquid may be
20、regulated to 10 6 5 mL/min.6. Test Specimen6.1 The test specimen shall consist of a piece of the material under test. The piece shall be cut to any shape convenient for easyidentification, but shall have dimensions that permit the most accurate position measurement of the center of volume of thesusp
21、ended specimen (Note 5). Care shall be taken in cutting specimens to avoid change in density resulting from compressivestress.NOTE 5The equilibrium positions of film specimens in the thickness range from 0.025 to 0.051 mm (0.001 to 0.002 in.) may be affected by interfacialtension. If this effect is
22、suspected, films not less than 0.127 mm (0.005 in.) in thickness shall be tested.6.2 The specimen shall be free of foreign matter and voids and shall have no cavities or surface characteristics that will causeentrapment of bubbles.7. Preparation of Density-Gradient Columns7.1 Preparation of Standard
23、 Glass Floats5Prepare glass floats by any convenient method such that they are fully annealed,approximately spherical, have a maximum diameter less than one fourth the inside diameter of the column, and do not interferewith the test specimens. Prepare a solution (400 to 600 mL) of the liquids to be
24、used in the gradient tube such that the density ofthe solution is approximately equal to the desired lowest density. When the floats are at room temperature, drop them gently intothe solution. Save the floats that sink very slowly, and discard those that sink very fast, or save them for another tube
25、. If necessaryto obtain a suitable range of floats, grind selected floats to the desired density by rubbing the head part of the float on a glass plate4 Tubes similar to those described in Refs (1) and (2) may also be used.5 Manufactured certified glass floats may be purchased.TABLE 1 Liquid Systems
26、 for Density-Gradient TubesSystem Density Range,g/cm3Methanol-benzyl alcohol 0.80 to 0.92Isopropanol-water 0.79 to 1.00Isopropanol-diethylene glycol 0.79 to 1.11Ethanol-carbon tetrachloride 0.79 to 1.59Toluene-carbon tetrachloride 0.87 to 1.59Water-sodium bromide 1.00 to 1.41Water-calcium nitrate 1.
27、00 to 1.60Carbon tetrachloride-trimethylene dibromide 1.60 to 1.99Trimethylene dibromide-ethylene bromide 1.99 to 2.18Ethylene bromide-bromoform 2.18 to 2.89D1505 182on which is spread a thin slurry of 400 or 500-mesh silicon carbide (Carborundum) or other appropriate abrasive. Progress shallbe foll
28、owed by dropping the float in the test solution at intervals and noting its change in rate of sinking.7.2 Calibration of Standard Glass Floats (see Appendix X1):7.2.1 Place a tall cylinder in the constant-temperature bath maintained at 23 6 0.1C. Fill the cylinder about two thirds full witha solutio
29、n of two suitable liquids selected from Table 1, the density of which can be varied over the desired range by the additionof either liquid to the mixture.After the cylinder and solution have attained temperature equilibrium, place the float in the solution,and if it sinks, add the denser liquid by s
30、uitable means with good stirring until the float reverses direction of movement. If the floatrises, add the less dense liquid by suitable means with good stirring until the float reverses direction of movement.7.2.2 When reversal of movement has been observed, reduce the amount of the liquid additio
31、ns to that equivalent to0.0001-g/cm3 density. When an addition equivalent to 0.0001-g/cm3 density causes a reversal of movement, or when the floatremains completely stationary for at least 15 min, the float and liquid are in satisfactory balance. The cylinder must be coveredwhenever it is being obse
32、rved for balance, and the liquid surface must be below the surface of the liquid in the constant-temperaturebath. After vigorous stirring, the liquid will continue to move for a considerable length of time; make sure that the observedmovement of the float is not due to liquid motion by waiting at le
33、ast 15 min after stirring has stopped before observing the float.7.2.3 When balance has been obtained, fill a freshly cleaned and dried pycnometer with the solution and place it in the 23 60.1C bath for sufficient time to allow temperature equilibrium of the glass. Determine the density of the solut
34、ion by normalmethods and make “in vacuo” corrections for all weighings. Record this as the density of the float. Repeat the procedure for eachfloat.7.3 Gradient Tube Preparation (see Annex A1 for details):7.3.1 Method AStepwise addition.7.3.2 Method BContinuous filling (liquid entering gradient tube
35、 becomes progressively less dense).7.3.3 Method CContinuous filling (liquid entering gradient tube becomes progressively more dense).8. Conditioning8.1 Test specimens whose change in density on conditioning is greater than the accuracy required of the density determinationshall be conditioned before
36、 testing in accordance with the method listed in the applicable ASTM material specification.9. Procedure9.1 Wet three representative test specimens with the less dense of the two liquids used in the tube and gently place them in thetube.Allow the tube and specimens to reach equilibrium, which will r
37、equire 10 min or more. Thin films of 1 to 2 mils in thicknessrequire approximately 112 h to settle, and rechecking after several hours is advisable (Note 4).9.2 Read the height of each float and each specimen by a line through the individual center of volume and averaging the threevalues. When a cat
38、hetometer is used, measure the height of the floats and specimens from an arbitrary level using a line throughtheir center of volume. If equilibrium is not obtained, the specimen may be imbibing the liquid.9.3 Remove old samples without destroying the gradient by slowly withdrawing a wire screen bas
39、ket attached to a long wire(Note 6), which is conveniently done by means of a clock motor. Withdraw the basket from the bottom of the tube and, aftercleaning, return it to the bottom of the tube. It is essential that this procedure be performed at a slow enough rate (approximately30 min/300-mm lengt
40、h of column) so that the density gradient is not disturbed.NOTE 6Whenever it is observed that air bubbles are collecting on samples in the column, a vacuum applied to the column will correct this.10. Calculation10.1 The densities of the samples may be determined graphically or by calculation from th
41、e levels to which the samples settleby either of the following methods:10.1.1 Graphical CalculationPlot float position versus float density on a chart large enough to be read accurately to 61 mmand the desired precision of density. A minimum correlation factor of 0.995 shall be obtained to show the
42、column is acceptable.Plot the positions of the unknown specimens on the chart and read their corresponding densities.10.1.2 Numerical CalculationCalculate the density by interpolation as follows:Density at x 5a1x 2y!b2a!/z 2y!# (2)where:a andb = densities of the two standard floats,y andz = distance
43、s of the two standards, a and b, respectively, bracketing the unknown measured from an arbitrary level, andx = distance of unknown above the same arbitrary level.11. Report11.1 Report the following information:11.1.1 Density reported as D23C, in grams per cubic centimetre, as the average for three r
44、epresentative test specimens,D1505 18311.1.2 Number of specimens tested if different than three,11.1.3 Sensitivity of density gradient in grams per cubic centimetre per millimetre,11.1.4 Complete identification of the material tested, and11.1.5 Date of the test.12. Precision and Bias612.1 Specimens
45、Molded in One Laboratory and Tested in Several LaboratoriesAn interlaboratory test was run in 1981 inwhich randomized density plaques were supplied to 22 laboratories. Four polyethylene samples of nominal densities of 0.92 to 0.96g/cm3 were molded in one laboratory. The data were analyzed using Prac
46、tice E691, and the results are given in Table 2.12.2 Specimens Molded and Tested in Several Laboratories:12.2.1 Samples Prepared Using Practice D4703 in Each LaboratoryTable 3 is based on a round robin6 conducted in 1994in accordance with Practice E691, involving seven materials tested by 7 to 11 la
47、boratories. For each material, all of the sampleswere prepared by each laboratory, molded in accordance with Procedure C of Annex A1 of Practice D4703, and tested using thistest method. The data are for comparison with the data of the same samples tested by Practice D2839. Each test result is anindi
48、vidual determination. Each laboratory obtained six test results for each material.12.2.2 Samples Prepared Using Practice D2839 in Each LaboratoryTable 4 is based on a round robin6 conducted in 1994in accordance with Practice E691, involving seven materials tested by 10 to 15 laboratories. For each m
49、aterial, all of the sampleswere prepared by each laboratory in accordance with Practice D2839. Each test result is an individual determination. Eachlaboratory obtained six test results for each material.12.3 Concept of r and RWarningThe following explanations of r and R (12.3 12.3.3) are only intended to present ameaningful way of considering the approximate precision of this test method. The data in Tables 2-4 shall not be rigorously appliedto acceptance or rejection of material, as those data are specific to the round robin and cannot be repres
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