1、Designation: D542 14Standard Test Method forIndex of Refraction of Transparent Organic Plastics1This standard is issued under the fixed designation D542; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、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 a procedure for measurin
3、g theindex of refraction of transparent organic plastic materials.1.2 A refractometer method is presented. This procedurewill satisfactorily cover the range of refractive indices foundfor such materials. Refractive index measurements requireoptically homogeneous specimens of uniform refractive index
4、.NOTE 1This test method and ISO 489 are technically equivalent.1.3 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 applic
5、a-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C162 Terminology of Glass and Glass ProductsD618 Practice for Conditioning Plastics for TestingD883 Terminology Relating to PlasticsE284 Terminology of AppearanceE691 Practice for Conducting an Interlaboratory
6、 Study toDetermine the Precision of a Test Method2.2 ISO Standard:ISO 489 Determination of the Refractive Index of Transpar-ent PlasticsPart A33. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this test method, seeTerminologies D883 and E284.3.1.2 dispersionvariation of refractive
7、 index with wavelength of light. C162, C143.1.3 index of refraction, nthe numerical expression of theratio of the velocity of light in a vacuum to the velocity of lightin a substance at a specified wavelength. E284, E124. Significance and Use4.1 This test method measures a fundamental property ofmat
8、ter which is useful for the control of purity and compositionfor simple identification purposes, and for optical parts design.This test method is capable of readability to four figures to theright of the decimal point.5. Apparatus5.1 The apparatus for this test method shall consist of anAbbe refract
9、ometer (Note 2), a suitable source of white light,and a small quantity of a suitable contacting liquid (Note 2 andNote 3).NOTE 2Other suitable refractometers can be used with appropriatemodification to this procedure as described in Section 7.NOTE 3Asatisfactory contacting liquid is one which will n
10、ot soften orotherwise attack the surface of the plastic within a period of2hofcontact.The index of refraction of the liquid must be higher, but not less than oneunit in the second decimal place, than the index of the plastic beingmeasured; for example, ndof the sample = 1.500, ndof the contactingliq
11、uid 1.510.6. Sampling6.1 Sampling shall be statistically adequate to ensure thatthe specimens were produced and obtained by a process instatistical control.6.2 Samples can be drawn from any materials presentation(for example, pellets, film, sheet, fabricated articles, etc.)which permits preparation
12、of a satisfactory specimen as de-scribed herein.7. Test Specimens7.1 The test specimen shall be of a size that will conve-niently fit on the face of the fixed half of the refractometerprisms (Note 4).Aspecimen measuring 6.3 by 12.7 mm on oneface is usually satisfactory.NOTE 4For maximum accuracy in
13、the refractometer method, the1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.40 on Optical Properties.Current edition approved March 1, 2014. Published March 2014. Originallyapproved in 1939. Last previous edition appr
14、oved in 2013 as D542 - 13. DOI:10.1520/D0542-14.2For 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.3Available fr
15、om 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 C700, West Conshohocken, PA 19428-2959. United States1surface
16、 contacting the prism must be flat. This surface is judged forflatness, provided the specimen has been satisfactorily polished, byobserving the sharpness of the dividing line between the light and darkfield as viewed in the ocular. A sharply defined straight dividing lineindicates satisfactory conta
17、ct between the specimen and prism surfaces.7.2 The surface to be used in contact with the prism shall beflat and shall have a good polish. A second edge surfaceperpendicular to the first and on one end of the specimen shallbe prepared with a fair polish (Note 5). The polished surfacesshall intersect
18、 without a beveled or rounded edge.NOTE 5It has been found possible to prepare a satisfactorily polishedsurface by hand polishing small specimens on an abrasive material backedby a piece of plate glass. Fine emery paper (for example, No. 000Behr-Manning polishing paper) followed by a polishing rouge
19、 compoundsuspended in water on a piece of parchment paper has successfully beenused as the abrasive to produce a polished surface.7.3 A minimum of three specimens are prepared and mea-sured.8. Conditioning8.1 ConditioningCondition the test specimens at 23 62C and 50 6 10 % relative humidity for not
20、less than 40 hprior to the test in accordance with Procedure A of PracticeD618. In cases of disagreement, the tolerances should be 61Cand 65 % relative humidity.8.2 Test ConditionsConduct tests at 23 6 2C and 50 610 % relative humidity, unless otherwise directed in a pertinentspecification. In cases
21、 of disagreement, the tolerances shall be61C and 65 % relative humidity. If the index of refraction ofthe material is found to be highly temperature dependent, thenthe temperature shall be accurately controlled to 23 6 0.2C.9. Procedure9.1 Remove the hinged illuminating prism from therefractometer,
22、if necessary. Place a source of diffuse polychro-matic light so that even illumination is obtained along the planeof the surface of contact between the specimen and therefractometer prism. Place a small drop of the suitable contact-ing liquid on the polished surface of the specimen and thenplace the
23、 specimen in firm contact with the surface of the prismwith the polished side of the specimen toward the specifiedlight source. Determine the index of refraction in the samemanner as specified for liquids. This shall be done by movingthe index arm of the refractometer until the field seen throughthe
24、 eyepiece is one-half dark. Adjust the compensator (Amiciprisms) drum to remove all color from the field of the ocular.Adjust the index arm using the vernier until the dividing linebetween the light and dark portions of the field exactlycoincides with the intersection of the cross hairs as seen in t
25、heeyepiece. Read the value of the index of refraction for theSodium D Line (see Note 6). Determine the dispersion byreading the compensator drum and applying this figure, alongwith the index of refraction, to a chart or table supplied withthe instrument.NOTE 6Sodium light from a sodium burner or dis
26、charge lamp is ofuse in increasing the precision of this test method as well as making thereading of the refractometer easier.9.2 In the case of nonisotropic materials, for example,injection- and compression-molded materials, the index ob-served is the average value for a thin layer of small area at
27、 apoint of contact near the center of the refractometer prism. Fora complete and accurate determination of the variation of theindex throughout the test specimen, it is necessary to make themeasurement at more than one point on the surface and withinthe body of the material. This can be done by prep
28、aring acontacting surface both perpendicular and parallel to themolding pressure or flow. After the test specimen is contactedto the prism it may be translated carefully for short distancesalong the prism surface in the direction of the light sourcewhile the variation of index is followed with the r
29、efractometer.This procedure shall be repeated a sufficient number of timesand for a sufficient number of specimens to determine the rangeof indices involved. The average value and the range of theindex readings obtained from these specimens shall be reportedif the range exceeds the accuracy of the m
30、easurement. If thevariations in index are systematic with the orientation of thetest specimen, and if these variations exceed those foundbetween specimens of the same material, the nature of thesevariations shall be reported with the average value.10. Report10.1 Report the following information:10.1
31、.1 The index of refraction to the nearest significantfigure warranted by the accuracy and duplicability of themeasurement. If the index is specified to more than threesignificant figures, the wavelength of light for which themeasurement was made shall be specified.NOTE 7Care should be taken to work
32、rapidly to avoid changes in therefractive index of the plastic due to its absorption of the contacting liquid.10.1.2 The temperature in degrees Celsius at which theindex was measured.10.1.3 If available, the dispersion shall be reported alongwith the index of refraction.11. Precision and Bias411.1 P
33、recisionA limited round robin was conducted in1978, involving seven materials (four polymers and three glassstandards) tested by four laboratories. An individual determi-nation is a test result. Each laboratory obtained six test resultsfor each material (three determinations on two different days).S
34、tatistical tests indicated there is no significant difference in theaverages or variances from Day 1 to Day 2 so that both daysdata were combined. The data in Table 1 and Table 2 are basedon this round robin.11.1.1 Because of the limited number of laboratories par-ticipating in this round robin, int
35、erpretation of SRand IRis notrecommended.11.1.2 Anyone wishing to participate in the development ofprecision and bias data for this test method should contact theChairman, Subcommittee D20.40, through ASTM Headquar-ters.NOTE 8The following explanations of Irand IR(11.3 11.3.3) areonly intended to pr
36、esent a meaningful way of considering the approximateprecision of this test method. The data in Table 1 and Table 2 should not4Supporting data are available from ASTM Headquarters. Request ResearchReport RR: D20 1154.D542 142be rigorously applied to acceptance or rejection of material, as those data
37、are specific to the round robin and may not be representative of other lots,conditions, materials, or laboratories.11.2 Users of this test method shall apply the principlesoutlined in Practice E691 to generate data specific to theirlaboratory and materials, or between specific laboratories. Theprinc
38、iples of 11.3 11.3.3 would then be valid for such data.11.3 Concept of Irand IRIf Srand SRhave beencalculated from a large enough body of data, and for test resultsthat were from testing one specimen:11.3.1 Ir: RepeatabilityComparing two test results for thesame material, obtained by the same operat
39、or using the sameequipment on the same day, the two test results shall be judgednot equivalent if they differ by more than the Irvalue for thatmaterial.11.3.2 IR: ReproducibilityComparing two test results forthe same material, obtained by different operators using differ-ent equipment on different d
40、ays, the two test results should bejudged not equivalent if they differ by more than the IRvaluefor that material.11.3.3 Any judgment in accordance with 11.3.1 and 11.3.2would have an approximate 95 % (0.95) probability of beingcorrect.11.4 BiasBias is the systematic error which contributes tothe di
41、fference between a test result and a true (or reference)value.11.4.1 The data for bias was determined from the threecertified glass standards and is reported in Table 2.12. Keywords12.1 dispersion; index of refractionAPPENDIX(Nonmandatory Information)X1. REFRACTIVE INDEX ROUND ROBINTABLE 1 Precision
42、Material Average SrASRBIrCIRDGlass Standard No. 1 1.356 0.001 0.002 0.003 0.006PTFE 1.366 0.001 0.002 0.003 0.006PVCA 1.477 0.002 0.002 0.006 0.006Glass Standard No. 2 1.490 0.002 0.003 0.006 0.008PA66 0.537 0.002 0.003 0.006 0.008Glass Standard No. 3 1.567 0.001 0.002 0.002 0.006PF 1.614 0.004 0.00
43、4 0.011 0.011ASr= within-laboratory standard deviation.BSR= between-laboratories standard deviation.CIr= 2.83 Sr.DIR= 2.83 SR.TABLE 2 BiasMaterialCertifiedValueTestAverageBiasStatisticallySignificantAGlass Standard No. 1 1.3554 1.3556 +0.0002 NoGlass Standard No. 2 1.4903 1.4897 0.0006 NoGlass Stand
44、ard No. 3 1.5684 1.5673 0.0011 YesA“t”-test ( = 0.05) = bias/Sr/n).TABLE X1.1 Test of Variance Between DaysMaterial Sr(1)ASr(2)AFBSR(1)ASR(2)AFBStandard Glass No. 1 0.011 0.007 2.47 0.0016 0.0017 1.13PTFE 0.0015 0.0016 1.14 0.0017 0.0016 1.13PVAC 0.0023 0.0016 2.07 0.0024 0.0016 2.25Standard Glass N
45、o. 2 0.0023 0.0021 1.20 0.0029 0.0026 1.24PA66 0.0021 0.0025 1.42 0.0032 0.0025 1.64Standard Glass No. 3 0.0008 0.0007 1.31 0.0019 0.0021 1.22PF 0.0050 0.0051 1.04 0.0050 0.0051 1.04A(1)/(2) (1) = day 1 data, (2) = day 2 data.BF 0.95 (2,2) = 19.00.D542 143SUMMARY OF CHANGESCommittee D20 has identifi
46、ed the location of selected changes to this standard since the last issue (D542 - 13)that may impact the use of this standard. (March 1, 2014)(1) Removed reference to Practice D1898 from 2.1 and 6.1. (2) Revised 6.1.Committee D20 has identified the location of selected changes to this standard since
47、 the last issue(D542 - 00(2006) that may impact the use of this standard. (September 1, 2013)(1) Corrected permissive language throughout the standard.(2) Moved former NOTE 7 to 9.2 since these are proceduralinstructions or alternatives, and are not to be placed in notes.(3) Renumbered NOTES 8 and 9
48、 to Note 7 and Note 8.ASTM 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 rights, and the riskof infringeme
49、nt of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not re
