1、Designation: D 4243 99 (Reapproved 2004)e1An American National StandardStandard Test Method forMeasurement of Average Viscometric Degree ofPolymerization of New and Aged Electrical Papers andBoards1This standard is issued under the fixed designation D 4243; the number immediately following the desig
2、nation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEReferences to IEC 450 were replaced
3、with IEC 60450 in 2.2 and 4.2 editorially in December 2004.1. Scope1.1 This test method describes a standard procedure fordetermining the average viscometric degree of polymerization(abbreviated DPv) of new or aged electrical papers. Thedetermination is made by measuring the intrinsic viscosity of a
4、solution of the paper in an appropriate solvent.1.2 The degree of polymerization (or the degree of conden-sation) of a particular cellulose molecule is the number ofanhydro-b-glucose monomers, C6H10O5, in the cellulose mol-ecule. Within a sample of paper, not all the cellulose moleculeshave the same
5、 degree of polymerization so that the mean valuemeasured by viscometric methods is not necessarily the sameas that which may be obtained by other methods.1.3 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns
6、, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and todetermine the applicability of regulatory limitations prior touse. See Section 92. Referenced Documents2.1 ASTM Standards:2D 445 Test Method for Kinematic
7、 Viscosity of Transparentand Opaque Liquids (and the Calculation of DynamicViscosity)D 1711 Terminology Relating to Electrical Insulation2.2 Other Document:IEC Publication 60450 Measurement of the Average Visco-metric Degree of Polymerization of New and AgedElectrical Papers33. Terminology3.1 Defini
8、tionsFor definitions of terms used in this testmethod, refer to Terminology D 1711.4. Summary of Test Method4.1 This test method measures the specific viscosity of asolution of the paper in cupriethylenediamine. From thismeasurement the intrinsic viscosity of the solution is deduced,and from this th
9、e degree of polymerization is easily calculated.4.2 This test method follows very closely the proceduresspecified in IEC 60450.5. Significance and Use5.1 This test method may be applied to all papers made fromunmodified cellulose, as used in transformer, cable, or capaci-tor manufacture. It applies
10、to new or aged papers. Forinformation, Appendix X2 shows an example of statisticaldistribution of DPvvalues for new papers intended for theinsulation of transformers, together with information relative tocable and capacitor papers. Nevertheless, where evaluating thedecomposition stage of aged papers
11、, take care to use, as areference, the DPvvalue of the new paper of the very sameorigin; DPvof new papers being a function, among otherfactors, of their specific gravity and of their manufacturingprocess.5.2 This test method can also be used for the determinationof the intrinsic viscosity of solutio
12、ns of chemically modifiedpapers, provided that these dissolve completely in the selectionsolvent. This test method should be used with caution when itis applied to papers with mineral fillers.1This test method is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Mat
13、erials and is the direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products.Current edition approved April 10, 1999. Published June 1999. Originallyapproved in 1983. Last previous edition approved in 1998 as D 4243 86 (1998).2For referenced ASTM standards, visit the ASTM webs
14、ite, 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 from American National Standards Institute, 11 W. 42nd St., 13thFloor, New York, NY 10036.1Copyright
15、ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Interferences6.1 Lignins, that are present in measurable amounts in mostpapers and boards, may have an effect on the test results,depending upon concentration and composition. For this rea-son,
16、 it is important in aging studies to use as a referencesamples of the unaged paper as mentioned in 5.1.6.2 Under some conditions of heat and atmosphere, crosslinking of cellulose molecules may occur, resulting in erratictest values. This effect has been observed for capacitor tissue invacuum at temp
17、eratures as low as 110 C and for other papersaged in air at higher temperatures.7. Apparatus7.1 Apparatus for Solution:7.1.1 Round-Bottomed 50-mL Flask, preferably with a shortnarrow neck, or a narrow-necked 50-mL Erlenmeyer flask.7.1.2 Rubber Stopper, fitting the neck of the flask, throughwhich pas
18、ses a capillary tube fitted with a small-bore cockglass cock; or a ground stopper, fitted with a small-bore cockmay be used with a ground-neck flask.7.1.3 Glass Balls, 4 to 6-mm diameter, that shall not be ableto enter the bore of the cock.7.1.4 Mechanical Stirrer, to rotate the solution flask with
19、auniform circular motion with a horizontal axis between 20 and40 r/min. The flask shall be mounted so that its axis is normalto the axis of rotation, and the radius of gyration shall not begreater than 200 mm.7.2 Apparatus for Measurement of Viscosity:7.2.1 Apparatus for Measurement of Kinematic Vis
20、cosity,asdescribed in Test Method D 445. The viscometer shall have acalibration constant, C, of from 0.00010 or 0.00013 St/s (10 3109to 13 3 109m2/s2).7.2.2 This constant shall be determined by measuring theefflux-time T (seconds) of a liquid of known dynamic viscosity(Ns/m2) and density r (g/cm3).
21、It is given by the formula:C 5hr T(1)7.2.3 Constant-Temperature Water Bath, regulated at 20 60.1 C.7.2.4 Stopwatch, with an accuracy of 0.1 s.7.3 Apparatus for Measurement of Water Content of PaperSample:7.3.1 Weighing Containers, impermeable to water vapor,with airtight lids.7.3.2 Ventilated Drying
22、 Oven, thermostatically controlled at105 6 2 C.7.3.3 Desiccator.8. Reagents8.1 Cupriethylene-Diamine Solution:8.1.1 The formula ascribed to cupriethylene-diamine (CED)is:CuNH22 CH22 CH2NH2!2#OH!2(2)This implies a molar ratio of 2 between the concentration ofethylene-diamine and the concentration of
23、copper:CED/Ccu! 5 2 (3)8.1.2 Cupriethylene-diamine solution may be purchasedcommercially at several different concentrations. At a concen-tration greater than 1 M it may be kept for one year in the dark.It is diluted to 1 M when required for use. Alternatively theCED solution can be made in the labo
24、ratory at its workingstrength of 1 M by the methods described in Annex A1.8.1.3 The 1 M solution will keep only for a limited time. Asoften as necessary the solution should be checked by:8.1.3.1 Using the method described in Annex A2 to verifythat the ratioCED/CCu5 2.0 6 0.1. (4)8.1.3.2 Verify that
25、there is no precipitate in the solution.Anyprecipitate should be removed by filtering or by decanting.9. Preparation of Specimens9.1 Impregnated Papers:9.1.1 Using a Soxhlet extractor, degrease the paper withhexane or, if necessary, with chloroform.9.1.1.1 CautionChloroform is toxic, and hexane is f
26、lam-mable. Adequate precautions must be taken to avoid exposureto vapors and to prevent fire.9.1.2 Allow the solvent to evaporate in air at room tempera-ture.9.1.3 Cut the sample into small pieces (1 or 2 mm2) withscissors, using gloves to avoid touching the paper.9.1.4 Keep the sample in a controll
27、ed-humidity atmosphereuntil it reaches equilibrium water content before removing thematerial required for test purposes.9.2 Nonimpregnated Papers:9.2.1 Cut the sample into small pieces (1 or 2 mm2) withscissors, using gloves to avoid touching the paper.9.2.2 Keep the sample in a controlled-humidity
28、atmosphereuntil it reaches equilibrium water content before removing thematerial required for test purposes.10. Procedure10.1 Determination of Viscosity:10.1.1 Test SpecimenWeigh to the nearest 0.1 mg anamount (m) of paper, in equilibrium with the controlledatmosphere, of about:10.1.1.1 125 mg when
29、DPvlies between 100 and 300,10.1.1.2 50 mg when DPvlies between 300 and 700, and10.1.1.3 25 mg when DPvlies between 700 and 1500.10.1.2 Solution:10.1.2.1 Put a few glass balls in the flask.10.1.2.2 Add the weighed test specimen.10.1.2.3 Carefully shake or stir by hand to ensure the smallpieces of pa
30、per are separated and evenly distributed.10.1.2.4 Add 22.5 mL of distilled water.10.1.2.5 Again shake or stir by hand to disintegrate and wetall the paper completely.10.1.2.6 Leave for12 h to allow thorough impregnation withwater.10.1.2.7 Add 22.5 mL of 1 M solution of cupriethylene-diamine.D 4243 9
31、9 (2004)e1210.1.2.8 Add a number of glass balls so that, when thestopper with capillary tube, and so forth, is fitted, the liquidwill entirely fill the flask and reach the bore of the cock. Do notallow any pieces of paper to enter the capillary, for such paperwill not be dissolved.10.1.2.9 Close the
32、 cock.10.1.2.10 Allow the specimen to dissolve with mechanicalstirring as described in 7.1.4. The preferred solution time is 2h; however, when the specimen is not satisfactorily dissolved,the solution time may be increased to a maximum of 18 h. Fora specimen of an aged paper, there is little risk of
33、 furthermeasurable degradation due to this increase of solution time.10.1.3 Measurement of Viscosity:10.1.3.1 After the period of stirring and before filling theviscometer, allow the solution to stand for 1 h at the tempera-ture of measurement, 20 6 0.1 C.10.1.3.2 Take the required volume of solutio
34、n and transfer itto the viscometer reservoir.Assemble the viscometer and placethe assembly in the thermostatic bath.10.1.3.3 Wait 15 min before beginning the measurements.Then raise the liquid level above the upper mark of theviscometer either by means of air pressure or slight vacuum.Measure the ef
35、flux time between the upper and lower marks.Make three successive measurements. The difference betweenthe maximum and minimum time of flow shall be less than 0.5s. If this repeatability is not achieved, clean the viscometer asdescribed in 10.1.4. Take a second specimen of the solutionthat has been k
36、ept at the measurement temperature and make afurther series of three measurements. If again the difference isnot less than 0.5 s, take a new specimen of paper and preparea fresh solution.10.1.3.4 Under the same conditions, measure the flow timeof the solvent. This shall be between 90 and 110 s for t
37、heviscometer constant C stated in 6.2 (0.00010 # C # 0.00013).10.1.4 Cleaning the Viscometer:10.1.4.1 By aspiration, fill the tube with chromic-acid mix-ture and immediately empty it again.10.1.4.2 Rinse thoroughly with distilled water.10.1.4.3 Rinse twice with acetone or alcohol.10.1.4.4 Dry by mea
38、ns of compressed gas from a cylinder ordust-and-oil-free compressed air.10.1.5 Make all tests in duplicate, making up two separatesolutions from separately weighed specimens.10.2 Determination of Water Content of Paper:10.2.1 Test Specimen:10.2.1.1 Weigh to the nearest milligram approximately 2 gof
39、paper in equilibrium with the controlled-humidity atmo-sphere, and in a closed weighing container that has been driedand tared.10.2.1.2 If the paper sample is too small for2gtobereserved for determining its water content, use a smallerspecimen. However, if the amount of paper is only sufficientfor t
40、he viscometric measurements, its water content may bededuced from the moisture equilibrium curves and the relativehumidity of the conditioning atmosphere with which the paperwas in equilibrium. If equilibrium curves are not available forthe particular paper tested, the following average values maybe
41、 used as a first approximation for temperatures between 20and 27 C.Relative Humidity of Air, % Water Content of Air, %50656810.2.2 Measurement of Water Content:10.2.2.1 After weighing, open the container and place it,with the weighed test specimen and its cap, in the oven andheat at 1056 2 C until i
42、t reaches constant mass. This willnormally require from 4 to 18 h.10.2.2.2 After drying, replace the cap on the container andallow it to cool in a desiccator for about 45 min. After cooling,equalize the air pressures inside and outside the container byraising and lowering the cap quickly. Weigh the
43、container withthe specimen.10.2.3 Alternative procedures may be used to determine thewater content of the paper sample provided that it can beverified that the procedure used will give results that differfrom the results used in 10.2.2 by no more than 0.5 %.11. Calculation11.1 Concentration, c, of D
44、ry Paper in the Solution:11.1.1 The water content H of the paper, as a proportion ofthe dry weight, is as follows:H 5 M 2 M0/M0! (5)where:M = mass of the test sample used for determining thewater content before drying, g andM0= mass of this sample after drying, g.11.1.2 Knowing the mass, m, in grams
45、 of the test specimenand its water content, H, the concentration c (g/100 mL), of drypaper in the solution is given by:c 5 m 100/45! 1/1 1 H! (6)11.2 Specific Viscosity, hsThe densities of the solvent andof the solution are practically identical. Thus, the specificviscosity hsas defined in 4.2 is gi
46、ven by:hs5Ts2 T0T0(7)where:T0= mean efflux time of the solvent, andTs= mean efflux time of the solution.11.3 Intrinsic Viscosity h:11.3.1 The intrinsic viscosity is calculated using Martinsformula from the specific viscosity hsand the concentration c(g/100 mL), of dry paper.11.3.2 As Martins formula
47、 does not readily lend itself tocalculation of h, use Table 1, which contains values of theproduct hc as a function of hs.11.3.3 In Table 1, k = 0.14, which value has been foundexperimentally for the operating conditions described.11.4 Degree of Polymerization DPvThe average visco-metric degree of p
48、olymerization DPvis given by the equation:DPva5 h/K (8)D 4243 99 (2004)e13where:a= 1, andK = 7.5 3 103.12. Validity of Results12.1 Two conditions should be met if the results are to beconsidered significant:12.1.1 Both values DPvshould agree within 2.5 % of theirmean value.12.1.2 After measuring the
49、 viscosity, filter the solutionthrough a fine-sintered glass filter; wash the filter and anydeposit with hydrochloric acid (diluted with one part water tothree parts acid), then with distilled water; dry in an oven ofabout 110 C, allow to cool in a desiccator, and weigh. Themass of any insoluble residue shall be less than 5 % of theinitial weight of the specimen.12.2 If one or both of these conditions are not met, a furtherseries of tests shall be made. If, again, one or both requirementsare not complied with, the values obtained are consi
