1、Designation: D4883 18Standard Test Method forDensity of Polyethylene by the Ultrasound Technique1This standard is issued under the fixed designation D4883; 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 () 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 te
3、st method is based on the distinct behaviors of theamorphous and crystalline phases of polyethylene in responseto ultrasound. Polyethylene shall be viewed as a compositestructure where high-density crystalline regions are connectedby lower-density amorphous material. The ratio of crystallineto amorp
4、hous 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 ofcrystallinit
5、y).1.3 Inorganic materials increase density as measured by TestMethods D792 and D1505, 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 parenthe
6、ses 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, health, and environmental practices and deter-mine the applicability of regulat
7、ory limitations prior to use.NOTE 1There is no known ISO equivalent to this standard.1.6 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, Gu
8、ides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D618 Practice for Conditioning Plastics for TestingD792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by Displacement
9、D883 Terminology Relating to PlasticsD1248 Specification for Polyethylene Plastics ExtrusionMaterials for Wire and CableD1505 Test Method for Density of Plastics by the Density-Gradient TechniqueD3350 Specification for Polyethylene Plastics Pipe and Fit-tings MaterialsD4703 Practice for Compression
10、Molding ThermoplasticMaterials into Test Specimens, Plaques, or SheetsD4976 Specification for Polyethylene Plastics Molding andExtrusion MaterialsE494 Practice for Measuring Ultrasonic Velocity in Materi-alsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Met
11、hodE2935 Practice for Conducting Equivalence Testing inLaboratory Applications3. Terminology3.1 DefinitionsThe definitions given in TerminologyD883, as well as in Test Methods D792 and D1505, areapplicable to this test method.4. Significance and Use4.1 The density of polyethylene is a conveniently m
12、easur-able property which is frequently useful as a means offollowing physical changes in 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.1This test method is under the juri
13、sdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.70 on Analytical Methods.Current edition approved Nov. 1, 2018. Published November 2018. Originallyapproved in 1989. Last previous edition approved in 2008 as D488308, which waswithdrawn January 2017 and r
14、einstated in November 2018. DOI: 10.1520/D4883-18.2For 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 standards Document Summary page onthe ASTM website.*A Summary
15、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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in
16、the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.15. Apparatus5.1 Use an instrument which utilizes a sonic technique toevaluate the density of polyethylene. The DS 5
17、00 instrument3utilizes 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
18、must beelectronically 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 D1505.5.3 Equipment specified in Test Methods D792.5.4 Equipment specified in Practice D618.5.5 Equipment specifi
19、ed in Practice D4703, Annex 1.NOTE 2The equipment specified in 5.2 or 5.3 is required for the initialcalibration 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
20、for any additionalcalibration when needed. It is also recommended that one or more of thecalibration standards 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 i
21、nitialcalibration are available from various sources (such as the NationalInstitute of Standards and Technology (NIST), resin manufacturers, and soforth).6. Test Specimens and Materials6.1 Test plaques shall be prepared in accordance to themolding procedure specified in Practice D4703, Annex 1,Proce
22、dure C.6.2 The test specimen shall consist of a piece of the materialunder test. Mold or cut the sample 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.)Len
23、gth 80100 (3.153.94)Width 3545 (1.381.77)Thickness 1.53 (0.060.12)A minimum thickness of 1.5 mm is required to provideproper specimen stiffness and for the instrument to distinguishsignal from echo. A maximum thickness of 3.0 mm is thethickness which the instrument sample holder allows.6.3 A sample
24、thickness of 1.9 6 0.2 mm shall be used inorder to be in compliance with Specifications D1248, D3350and D4976 for Polyethylene Plastics.6.4 Use the same plaque thickness for calibration samplesand testing samples.6.5 The specimen shall be free of foreign matter and voidsand shall have no surface mar
25、ks or other surface flaws.6.6 Use demineralized water for the testing equipmentswater bath.7. Conditioning7.1 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 D618, for those testswhere conditioning is req
26、uired. In cases of disagreement,specimens shall be conditioned at 23 6 1C and 50 6 5%relative humidity.7.2 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).7.3 Testin
27、g in normal plant operations frequently calls fortesting before the sample has become fully conditioned. It willbe necessary to establish a correlation between a predeterminedconditioning time (that is, 30 minutes in a water bath at23 6 2C (73.4 6 3.6F) and measured density and the mea-sured density
28、 when fully conditioned in accordance withProcedure A of Practice D618 and to apply the correlation toobtain the predicted density. Retain the sample and retest oncethe sample has been fully conditioned. If the measured densityof the retained specimen does not fall within 60.0004 of thepredicted den
29、sity then the conditioning time will need to beadjusted and a new correlation between measured and pre-dicted density will need to be created.8. Calibration8.1 Refer to instruments operating manual for details onoperating the instrument.8.2 The cleanliness of the demineralized water used in thewater
30、 bath shall be monitored and the water be replaced on aregular basis to avoid erroneous testing results.8.3 Resins to be utilized for calibration shall be molded intoplaques in accordance with Practice D4703 Annex 1, Proce-dure C and be conditioned in accordance with Procedure A ofPractice D618. Spe
31、cimens to be used for calibration shallundergo full conditioning.8.4 Determine the density value of the specimen in accor-dance with Test Methods D792 or D1505. Conduct thedeterminations as specified by the test methods, that is, twodeterminations for D792 or three determinations for D1505.Calculate
32、 a mean density value for the sample plaque.8.5 Evaluate each plaque on ultrasound instrument and usethe mean density obtained in 8.4 for calibration. Use either thesame sample plaque used in 8.4 or another plaque molded fromthe same resin sample. This is considered as one data point. Sixdata points
33、 are recommended per resin sample.8.6 The absolute accuracy of the data acquired is directlycorrelated to the accuracy of the calibration curve. This curveshall be made up of as many data points as possible and coverthe entire density range of interest. A minimum of 30 datapoints per calibration cur
34、ve is required. More data points arerecommended if a broad density range is to be measured. Thesedata points shall be evenly spread throughout the density range.3The sole source of supply of the DS 500 instrument known to the committee atthis time is Deguise Technologies, Inc., 11755 Rue de Guise, Q
35、uebec City (PQ),Canada, G2A 3K6; Phone: (418) 845-9064; (email:jraymondb2b2c.ca). If you areaware of alternative suppliers, please provide this information to ASTM Interna-tional Headquarters. Your comments will receive careful consideration at a meetingof the responsible technical committee,1which
36、you may attend.D4883 1828.7 Because this test method is based on electronic tech-niques as compared to physical methods, it is imperative thatthe electronics be calibrated correctly. The electronics shall bere-calibrated when the transducer or the board is replaced.NOTE 3Numerous product attributes
37、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 nature is made to the product.9. Sample Tes
38、ting9.1 Place the test specimen in the instruments water bathand allow it to condition for approximately 10 minutes prior tomeasurement to allow the specimen to become properly wettedand at the proper temperature.9.2 For the most accurate results, test each sample fourtimes (from different locations
39、 on the specimen) and determinethe average. If the density of one determination is equal orgreater than 60.0004 g/cm3from the average, discard thisdetermination. If two determinations are equal or greater than60.0004 g/cm3from the average, make a new plaque. If datahas demonstrated that the resin sa
40、mples have good uniformity,one determination per sample will be sufficient.NOTE 4In the case that deviation from the average is caused byinadequate conditioning of the sample in the bath, place the sample backin the bath for an additional five minutes then re-measure the density.10. Report10.1 Repor
41、t the following information:10.1.1 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 averagedensity reported as D23C = _ g cm3.10
42、.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 Bias411.1 PrecisionTable 1 is based on a round robin con-ducted in 1987 in accordance with Practice E691,
43、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 results for each material under evaluation
44、from eachlaboratory.11.2 Concept of r and RWarningThe following expla-nations of r and R (11.2 through 11.2.3) are only intended topresent a meaningful way of considering the approximateprecision of this test method. The data in Table 1 shall not berigorously applied to acceptance or rejection of ma
45、terial, asthose data are specific to the round robin and are not to beconsidered representative of other lots, conditions, materials,or laboratories. Users of this test method shall apply theprinciples outlined in Practice E691 to generate data specific totheir laboratory and materials, or between s
46、pecific laboratories.The principles of 11.2 through 11.2.3 shall then be valid forsuch data.If Srand SRhave been calculated from a large enough bodyof data, and for test results that were averages from testing onespecimen:11.2.1 Repeatability Limit, rThe value below which theabsolute difference betw
47、een two individual test results obtainedunder repeatability conditions is likely to occur with a prob-ability of approximately 0.95 (95 %).11.2.2 Reproducibility Limit, RThe value below which theabsolute difference between two individual test results obtainedunder reproducibility conditions is likel
48、y to occur with aprobability of approximately 0.95 (95 %).11.2.3 Conducting equivalence testing on numerical datafrom two sources shall be conducted in accordance withPractice E2935 or any known method for judging the equiva-lence of two means, for example, a t-test.11.3 BiasThere are no recognized
49、standards by which toestimate the bias of this test method.12. Keywords12.1 amorphous; crystalline; density; molded; plaques;polyethylene; sonic; ultrasonic; ultrasound4Supporting data are available from ASTM Headquarters. Request RR:D20-1157.TABLE 1 Precision DataMaterial Average SrASRBrCRD1 0.9216 0.00029 0.00128 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 obtainedby pooling th
