1、Designation: D 4883 03Standard Test Method forDensity of Polyethylene by the Ultrasound Technique1This standard is issued under the fixed designation D 4883; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision
2、. A number 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 the determination of the densityof polyethylene through the utilization of ultrasound equip-ment.1.2 This
3、 test method is based on the distinct behaviors of theamorphous and crystalline phases of polyethylene in responseto ultrasound. Polyethylene can be viewed as a compositestructure where high-density crystalline regions are connectedby lower-density amorphous material. The ratio of crystallineto amor
4、phous material determines the final density of thematerial. The amorphous and crystalline phases exhibit verydistinct behaviors with regard to the propagation of soundwaves. The propagation characteristics in the composite willdepend on the relative amount of the two phases (the degree ofcrystallini
5、ty).1.3 Inorganic materials increase density as measured by TestMethods D 792 and D 1505, but they have little or no effect onultrasonic density. The ultrasonic measurement is basically abase resin density.1.4 The values stated in SI units are to be regarded as thestandard. The values given in paren
6、theses are for informationonly.1.5 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 limitatio
7、ns prior to use.NOTE 1There is no similar or equivalent ISO standard.2. Referenced Documents2.1 ASTM Standards:D 618 Practice for Conditioning Plastics for Testing2D 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by Displacement2D 883 Terminology Relating to Plasti
8、cs2D 1248 Specification for Polyethylene Plastics: ExtrusionMaterials for Wire and Cable2D 1505 Test Method for Density of Plastics by the Density-Gradient Technique2D 3350 Specification for Polyethylene Plastics: Pipe andFittings Materials3D 4703 Practice for Compression Molding ThermoplasticMateri
9、als into Test Specimens, Plaques, or Sheets3D 4976 Specification for Polyethylene Plastics: Moldingand Extrusion Materials4E 494 Practice for Measuring Ultrasonic Velocity in Mate-rials5E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method63. Terminology3.
10、1 Definitions: The definitions given in TerminologyD 883, as well as in Test Methods D 792 and D 1505, areapplicable to this test method.4. Significance and Use4.1 The density of polyethylene is a conveniently measur-able property which is frequently useful as a means offollowing physical changes in
11、 a sample, as an indication ofuniformity among samples, and as a means of identification.4.2 This test method is designed to yield results with aprecision of 60.08 % or better.5. Apparatus5.1 Use an instrument which utilizes a sonic technique toevaluate the density of polyethylene. The DS 500 instru
12、ment7utilizes a sonic sensing head (transducer) which measures thevelocity of sound in a molded specimen. Because sonicvelocity is positively correlated to density in polyethylene, ameasurement of this velocity is used to determine specimendensity. The information from this transducer then must beel
13、ectronically evaluated; in the DS 500 instance this is donewith a computer, and the result is reported either through adisplay or printout.5.2 Equipment specified in Test Method D 1505.1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Su
14、bcommittee D20.70 on Analytical Methods,Section 01, Physical Methods.Current edition approved July 10, 2003. Published September 2003. Originallyapproved in 1989. Last previous edition approved in 1999 as D 4883 99.2Annual Book of ASTM Standards, Vol 08.01.3Annual Book of ASTM Standards, Vol 08.02.4
15、Annual Book of ASTM Standards, Vol 08.03.5Annual Book of ASTM Standards, Vol 03.03.6Annual Book of ASTM Standards, Vol 14.02.7The DS 500 instrument can be obtained from R/D Tech (www.rd-) orUltra Optec ().1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International
16、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 Equipment specified in Test Methods D 792.5.4 Equipment specified in Practice D 618.5.5 Equipment specified in Practice D 4703, Annex 1.NOTE 2The equipment specified in 5.2 or 5.3 is required for the initialcal
17、ibration of the sonic equipment. Once the equipment is calibrated, thisadditional equipment is no longer required. It is recommended that thestandards used for the initial calibration be retained for any additionalcalibration when needed. It is also recommended that one or more of thecalibration sta
18、ndards be evaluated on a routine basis for calibrationverification. The absolute accuracy of data produced will not be better thanthis initial calibration and continued verification. Samples for initialcalibration are available from various sources (such as the NationalInstitute of Standards and Tec
19、hnology (NIST), resin manufacturers, and soforth).6. Test Specimens and Materials6.1 Test plaques shall be prepared in accordance to themolding procedure specified in Practice D 4703, Annex 1,Procedure C.6.2 The test specimen shall consist of a piece of the materialunder test. Mold or cut the sample
20、 specimen to the specifieddimensions. When a sample piece is cut from a molded plaque,care must be taken to avoid change in density resulting fromcompressive stress.Specimen Dimensions, mm in.LengthWidthThickness8010035451.533.153.941.381.770.060.12NOTE 3A minimum thickness of 1.5 mm is required to
21、provide properspecimen stiffness and for the instrument to distinguish signal from echo.A maximum thickness of 3.0 mm is the thickness which the instrumentsample holder allows.NOTE 4A sample thickness of 1.9 6 0.2 mm shall be used in order tobe in compliance with Specifications D 1248, D 3350 and D
22、4976 forPolyethylene Plastics.6.3 Use the same plaque thickness for calibration samplesand testing samples.6.4 The specimen shall be free of foreign matter and voidsand shall have no surface marks or other surface flaws.6.5 Use demineralized water for the testing equipmentswater bath.7. Conditioning
23、7.1 ConditioningCondition the test specimens at23 6 2C 73.4 6 3.6F for not less than 40 h prior to test inaccordance with Procedure A of Practice D 618, for those testswhere conditioning is required. In cases of disagreement,specimens shall be conditioned at 23 6 1C and 50 6 5%relative humidity.7.2
24、Test ConditionsConduct tests in instruments waterbath at a temperature of 23 6 2C 73.4 6 3.6F unlessotherwise specified. In cases of disagreement, the tolerancesshall be 61C 1.8F.NOTE 5Testing in normal plant operations frequently calls for testingbefore the sample has become fully conditioned. It w
25、ill be necessary toestablish a correlation between the conditioning time and measureddensity and to apply the correlation to obtain the predicted density. If thespecimens have not reached a level of stability that assures the densityaccuracy, the density determination shall be tested under test cond
26、itions inaccordance with the test method listed in the applicable ASTM specifi-cation.8. Calibration8.1 Refer to instruments operating manual for details onoperating the instrument.NOTE 6The cleanliness of the demineralized water used in the waterbath shall be monitored and the water be replaced on
27、a regular basis toavoid erroneous testing results.8.2 Resins to be utilized for calibration shall be molded intoplaques in accordance with Practice D 4703 Annex 1, Proce-dure C and be conditioned in accordance with Practice D 618.Specimens to be used for calibration shall undergo full condi-tioning.
28、NOTE 7One method of ensuring full conditioning is by aging at 70Cfor 24 h.8.3 Determine the density value of the specimen in accor-dance with Test Methods D 792 or D 1505. Conduct thedeterminations as specified by the test methods, that is, twodeterminations for D 792 or three determinations for D 1
29、505.Calculate a mean density value for the sample plaque.8.4 Evaluate each plaque on ultrasound instrument and usethe mean density obtained in 8.3 for calibration. Use either thesame sample plaque used in Section 8.3 or different plaques.This is considered as one data point. Six data points arerecom
30、mended per resin sample. Ensure that the moldedsamples acquired for Test Methods D 792 or D 1505 accuratelyrepresent the molded samples utilized for the ultrasonic cali-bration.8.5 The absolute accuracy of the data acquired is directlycorrelated to the accuracy of the calibration curve. This curvesh
31、all be made up of as many data points as possible and coverthe entire density range of interest. A minimum of 30 datapoints per calibration curve is required. More data points arerecommended if a broad density range is to be measured. Thesedata points shall be evenly spread throughout the density ra
32、nge.NOTE 8Numerous product attributes such as product family, reactorgeometry, catalyst, comonomer, additives and fillers, have been known toinfluence instrument calibration. Use different calibration curves fordifferent products when needed. Verify the calibration curve when anychange of this natur
33、e is made to the product.NOTE 9Because this test method is based on electronic techniques ascompared to physical methods, it is imperative that the electronics becalibrated correctly. The electronics shall be re-calibrated when thetransducer or the board is replaced.9. Sample Testing9.1 For the most
34、 accurate results, test each sample fourtimes and determine the average. If the density of onedetermination is equal or greater than 60.0004 g/cm3from theaverage, discard this determination. If two determinations areequal or greater than 6 0.0004 g/cm3from the average, makea new plaque. If data has
35、demonstrated that the resin sampleshave good uniformity, one determination per sample will besufficient.NOTE 10In the case that deviation from the average is caused byinadequate conditioning of the sample in the bath, place the sample backto the bath for an additional five minutes then re-measure th
36、e density.10. Report10.1 Report the following information:D488303210.1.1 Complete identification of the material or producttested, including method of specimen preparation and condi-tioning.10.1.2 Average specific gravity for all specimens from asampling unit, reported as sp gr 23/23C = _, or averag
37、edensity reported as D 23C = _ g/cm3.10.1.3 A measure of the degree of variation of specificgravity or density within the sampling unit such as the standarddeviation and number of determinations.10.1.4 Date of test.11. Precision and Bias811.1 PrecisionTable 1 is based on a round robin con-ducted in
38、1987 in accordance with Practice E 691, involvingfour materials tested by six laboratories. Each material wasmolded, with all specimens being prepared in one laboratory.Each material tested was represented by four specimens, andeach specimen was evaluated six times. This procedure yielded24 test res
39、ults for each material under evaluation from eachlaboratory.11.2 Concept of r and RWarningThe following explanations of r and R (11.2through 11.2.3) are only intended to present a meaningful wayof considering the approximate precision of this test method.The data in Table 1 should not be rigorously
40、applied toacceptance or rejection of material, as those data are specific tothe round robin and may not be representative of other lots,conditions, materials, or laboratories. Users of this test methodshould apply the principles outlined in Practice E 691 togenerate data specific to their laboratory
41、 and materials, orbetween specific laboratories. The principles of 11.2 through11.2.3 would then be valid for such data.If Srand SRhave been calculated from a large enough bodyof dat0a, and for test results that were averages from testingone specimen:11.2.1 Repeatability Limit, r (Comparing two test
42、 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 valuefor that material.11.2.2 Reproducibility Limit, R (Comparing two test re-sults for the same material, obtain
43、ed by different operatorsusing different equipment in different laboratories)The twotest results should be judged not equivalent if they differ bymore than the R value for that material.11.2.3 Any judgment in accordance with 11.2.1 or 11.2.2would have an approximate 95 % (0.95) probability of beingc
44、orrect.11.3 BiasThere are no recognized standards by which toestimate the bias of this test method.12. Keywords12.1 amorphous; crystalline; density; molded; plaques;polyethylene; sonic; ultrasonic; ultrasoundSUMMARY OF CHANGESThis section identifies the location of selected changes to this test meth
45、od. For the convenience of the user,Committee D20 has highlighted those changes that may impact the use of this test method. This section may alsoinclude descriptions of the changes or reasons for the changes, or both.D 4883 03:(1) Added to Referenced Documents: D 1248, D 3350, D 4703,D 4976, and E
46、494.(2) Added Note 3, 4, 8, 10 and Section 9.1.(3) Combine Notes 6 and 7 of the previous revision into Note5.(4) Deleted the relative humidity requirement for testing.(5) Clarified the number of determinations needed for calibra-tion and sample testing.(6) Deleted instruments operating procedures.(7
47、) Removed non-mandatory languages.D 4883 96:(1) Added an ISO equivalency statement and sections onkeywords and precision and bias.D 4883 99:Added Note 7.8Supporting data are available from ASTM Headquarters. Request RR: D20-1157.TABLE 1 Precision DataMaterial Average SrASRBrCRD1 0.9216 0.00029 0.001
48、28 0.00082 0.003622 0.9187 0.00047 0.00107 0.00133 0.003023 0.9341 0.00073 0.00148 0.00207 0.004194 0.9516 0.00039 0.00127 0.00110 0.00359ASr= within-laboratory standard deviation for the indicated material. It is ob-tained by pooling the within-laboratory standard deviations of the test results fro
49、mall of the participating laboratories.BSR= between-laboratories reproducibility, expressed as standard deviation, forthe indicated material.Cr = within-laboratory repeatability limit = 2.8 Sr.DRR= between-laboratories reproducibility limit = 2.8 SR.D4883033ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent
