1、Designation: D4243 99 (Reapproved 2009)An 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 D4243; the number immediately following the designati
2、on 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a standa
3、rd 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 asolution of the paper in an appropriate solvent.1.2 The degree of polymerization (or the degree of conden-
4、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 degree of polymerization so that the mean valuemeasured by viscometric methods is not necessarily the sam
5、eas 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, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish approp
6、riate safety and health practices and todetermine the applicability of regulatory limitations prior touse. See Section 92. Referenced Documents2.1 ASTM Standards:2D445 Test Method for Kinematic Viscosity of Transparentand Opaque Liquids (and Calculation of Dynamic Viscos-ity)D1711 Terminology Relati
7、ng to Electrical Insulation2.2 Other Document:IEC 60450 Measurement of the Average Viscometric De-gree of Polymerization of New and Aged ElectricalPapers33. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D1711.4. Summary of Test Method4.1 This test m
8、ethod measures the specific viscosity of asolution of the paper in cupriethylenediamine. From thismeasurement the intrinsic viscosity of the solution is deduced,and from this the degree of polymerization is easily calculated.4.2 This test method follows very closely the proceduresspecified in IEC 60
9、450.5. 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 to new or aged papers. Forinformation, Appendix X1 shows an example of statisticaldistribution of DPvvalues for new papers
10、intended for theinsulation of transformers, together with information relative tocable and capacitor papers. Nevertheless, where evaluating thedecomposition stage of aged papers, take care to use, as areference, the DPvvalue of the new paper of the very sameorigin; DPvof new papers being a function,
11、 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 solutions of chemically modifiedpapers, provided that these dissolve completely in the selectionsolvent. This test method should b
12、e 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 Materials and is the direct responsibility ofSubcommittee D09.19 on Dielectric Sheet and Roll Products.Current edition approve
13、d Oct. 1, 2009. Published February 2010. Originallyapproved in 1983. Last previous edition approved in 2004 as D4243 99(2004)1.DOI: 10.1520/D4243-99R09.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
14、ndards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036, http:/www.ansi.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohock
15、en, 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, it is important in aging studies to use as a referencesamples of the u
16、naged 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 temperatures as low as 110C and for other papersaged in air at higher tempe
17、ratures.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 passes a capillary tube fitted with a small-bore cockglass cock; or a groun
18、d 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 auniform circular motion with a horizontal axis between 20 and40 r/min.
19、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 Viscosity,asdescribed in Test Method D445. The viscometer shall have acalib
20、ration 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). It is given by the formula:C 5hr T(1)7.2.3 Constant-Temperature Water Bat
21、h, regulated at 20 60.1C.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 Oven, thermostatically controlled at105 6 2C.7.3.3 Desiccator.8. Reagents
22、8.1 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 copper:CED/Ccu! 5 2 (3)8.1.2 Cupriethylene-diamine solution may be purchase
23、dcommercially 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 laboratory at its workingstrength of 1 M by the methods described in Annex A1.8
24、.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 there is no precipitate in the solution.Anyprecipitate should be removed by
25、 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. (WarningChloroform is toxic, and hexane is flammable. Adequateprecautions must be taken to avoid exposure to vapors and topre
26、vent 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 controlled-humidity atmosphereuntil it reaches equilibrium water content before removing t
27、hematerial 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 atmosphereuntil it reaches equilibrium water content before removing thematerial r
28、equired 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 DPvlies between 100 and 300,10.1.1.2 50 mg when DPvlies between 300 and 700, and10
29、.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 paper are separated and evenly distributed.10.1.2.4 Add 22.5 mL of distilled water.1
30、0.1.2.5 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.D4243 99 (2009)210.1.2.8 Add a number of glass balls so that, when thestopper with capilla
31、ry 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 cock.10.1.2.10 Allow the specimen to dissolve with mechanicalstirring as described i
32、n 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 furthermeasurable degradation due to this increase of solution time.10.1.3 Measureme
33、nt 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 0.1C.10.1.3.2 Take the required volume of solution and transfer itto the viscometer reservoir.Assemble the viscometer and placethe asse
34、mbly 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 efflux time between the upper and lower marks.Make three successive measurements. The di
35、fference 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 kept at the measurement temperature and make afurther series of three measurements. If
36、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 theviscometer constant C stated in 6.2 (0.00010 # C # 0.00013).10.1.4 Cleaning the Visc
37、ometer: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 means of compressed gas from a cylinder ordust-and-oil-free compressed air.10.1.5 Make al
38、l 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 paper in equilibrium with the controlled-humidity atmo-sphere, and in a closed weighin
39、g 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 the viscometric measurements, its water content may bededuced from the moisture equilib
40、rium 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 used as a first approximation for temperatures between 20and 27C.Relative Humidity of
41、 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 105 6 2C until it reaches constant mass. This willnormally require from 4 to 18 h.10.2.2.2 After drying
42、, 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 container withthe specimen.10.2.3 Alternative procedures may be used to determine thewa
43、ter 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 Dry Paper in the Solution:11.1.1 The water content H of the paper, as a proportion ofthe
44、 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 of the test specimenand its water content, H, the concentration c (g/100 mL), of drypa
45、per 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 given by:hs5Ts2 T0T0(7)where:T0= mean efflux time of the solvent, andTs= mean efflux time
46、 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 does not readily lend itself tocalculation of h, use Table 1, which contains values of
47、 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.D4243 99 (2009)311.4 Degree of Polymerization DPvThe average visco-metric degree of polymerization DPvis given by the equation:DPva5 h/K (8)where:a= 1, andK
48、 = 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 viscosity, filter the solutionthrough a fine-sintered glass filter; wash the filter and a
49、nydeposit with hydrochloric acid (diluted with one part water tothree parts acid), then with distilled water; dry in an oven ofabout 110C, 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 considered to beresults, but the test report shall state that the above validityrequirements h
