ASTM D4243-99(2004)e1
(Test Method)Standard Test Method for Measurement of Average Viscometric Degree of Polymerization of New and Aged Electrical Papers and Boards
Standard Test Method for Measurement of Average Viscometric Degree of Polymerization of New and Aged Electrical Papers and Boards
SIGNIFICANCE AND USE
This test method may be applied to all papers made from unmodified cellulose, as used in transformer, cable, or capacitor manufacture. It applies to new or aged papers. For information, Appendix X2 shows an example of statistical distribution of values for new papers intended for the insulation of transformers, together with information relative to cable and capacitor papers. Nevertheless, where evaluating the decomposition stage of aged papers, take care to use, as a reference, the value of the new paper of the very same origin; of new papers being a function, among other factors, of their specific gravity and of their manufacturing process.
This test method can also be used for the determination of the intrinsic viscosity of solutions of chemically modified papers, provided that these dissolve completely in the selection solvent. This test method should be used with caution when it is applied to papers with mineral fillers.
SCOPE
1.1 This test method describes a standard procedure for determining the average viscometric degree of polymerization (abbreviated DPv) of new or aged electrical papers. The determination is made by measuring the intrinsic viscosity of a solution of the paper in an appropriate solvent.
1.2 The degree of polymerization (or the degree of condensation) of a particular cellulose molecule is the number of anhydro--glucose monomers, C6H10O5, in the cellulose molecule. Within a sample of paper, not all the cellulose molecules have the same degree of polymerization so that the mean value measured by viscometric methods is not necessarily the same as that which may be obtained by other methods.
This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use. See Section 9
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An American National Standard
´1
Designation: D4243 – 99 (Reapproved 2004)
Standard Test Method for
Measurement of Average Viscometric Degree of
Polymerization of New and Aged Electrical Papers and
Boards
This standard is issued under the fixed designation D4243; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—References to IEC 450 were replaced with IEC 60450 in 2.2 and 4.2 editorially in December 2004.
1. Scope 2.2 Other Document:
IEC Publication 60450 Measurement of theAverage Visco-
1.1 This test method describes a standard procedure for
metric Degree of Polymerization of New and Aged
determining the average viscometric degree of polymerization
Electrical Papers
(abbreviated DP ) of new or aged electrical papers. The
v
determination is made by measuring the intrinsic viscosity of a
3. Terminology
solution of the paper in an appropriate solvent.
3.1 Definitions—For definitions of terms used in this test
1.2 The degree of polymerization (or the degree of conden-
method, refer to Terminology D1711.
sation) of a particular cellulose molecule is the number of
anhydro-b-glucose monomers, C H O , in the cellulose mol-
6 10 5
4. Summary of Test Method
ecule.Withinasampleofpaper,notallthecellulosemolecules
4.1 This test method measures the specific viscosity of a
havethesamedegreeofpolymerizationsothatthemeanvalue
solution of the paper in cupriethylene–diamine. From this
measured by viscometric methods is not necessarily the same
measurement the intrinsic viscosity of the solution is deduced,
as that which may be obtained by other methods.
andfromthisthedegreeofpolymerizationiseasilycalculated.
1.3 This standard may involve hazardous materials, opera-
4.2 This test method follows very closely the procedures
tions, and equipment. This standard does not purport to
specified in IEC 60450.
address all of the safety concerns, if any, associated with its
use. It is the responsibility of the user of this standard to
5. Significance and Use
establish appropriate safety and health practices and to
5.1 Thistestmethodmaybeappliedtoallpapersmadefrom
determine the applicability of regulatory limitations prior to
unmodified cellulose, as used in transformer, cable, or capaci-
use. See Section 9
tor manufacture. It applies to new or aged papers. For
information, Appendix X2 shows an example of statistical
2. Referenced Documents
2 distribution of DP values for new papers intended for the
v
2.1 ASTM Standards:
insulationoftransformers,togetherwithinformationrelativeto
D445 Test Method for Kinematic Viscosity of Transparent
cable and capacitor papers. Nevertheless, where evaluating the
and Opaque Liquids (and Calculation of Dynamic Viscos-
decomposition stage of aged papers, take care to use, as a
ity)
reference, the DP value of the new paper of the very same
v
D1711 Terminology Relating to Electrical Insulation
origin; DP of new papers being a function, among other
v
factors, of their specific gravity and of their manufacturing
This test method is under the jurisdiction of ASTM Committee D09 on
process.
Electrical and Electronic Insulating Materials and is the direct responsibility of
5.2 This test method can also be used for the determination
Subcommittee D09.19 on Dielectric Sheet and Roll Products.
of the intrinsic viscosity of solutions of chemically modified
Current edition approved April 10, 1999. Published June 1999. Originally
approved in 1983. Last previous edition approved in 1998 as D4243–86 (1998). papers,providedthatthesedissolvecompletelyintheselection
DOI: 10.1520/D4243-99R04E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available from American National Standards Institute, 11 W. 42nd St., 13th
the ASTM website. Floor, New York, NY 10036.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D4243 – 99 (2004)
solvent. This test method should be used with caution when it ~C /C ! 52 (3)
ED cu
is applied to papers with mineral fillers.
8.1.2 Cupriethylene-diamine solution may be purchased
commercially at several different concentrations.At a concen-
6. Interferences
trationgreaterthan1 Mitmaybekeptforoneyearinthedark.
6.1 Lignins, that are present in measurable amounts in most
It is diluted to 1 M when required for use. Alternatively the
papers and boards, may have an effect on the test results,
CED solution can be made in the laboratory at its working
depending upon concentration and composition. For this rea-
strength of 1 M by the methods described in Annex A1.
son, it is important in aging studies to use as a reference
8.1.3 The 1 M solution will keep only for a limited time.As
samples of the unaged paper as mentioned in 5.1.
often as necessary the solution should be checked by:
6.2 Under some conditions of heat and atmosphere, cross
8.1.3.1 Using the method described in Annex A2 to verify
linking of cellulose molecules may occur, resulting in erratic
that the ratio
testvalues.Thiseffecthasbeenobservedforcapacitortissuein
C /C 52.0 60.1. (4)
ED Cu
vacuum at temperatures as low as 110 °C and for other papers
8.1.3.2 Verifythatthereisnoprecipitateinthesolution.Any
aged in air at higher temperatures.
precipitate should be removed by filtering or by decanting.
7. Apparatus
9. Preparation of Specimens
7.1 Apparatus for Solution:
9.1 Impregnated Papers:
7.1.1 Round-Bottomed 50-mL Flask, preferably with a short
narrow neck, or a narrow-necked 50-mL Erlenmeyer flask. 9.1.1 Using a Soxhlet extractor, degrease the paper with
hexane or, if necessary, with chloroform.
7.1.2 Rubber Stopper, fitting the neck of the flask, through
which passes a capillary tube fitted with a small-bore cock 9.1.1.1 Caution—Chloroform is toxic, and hexane is flam-
mable.Adequate precautions must be taken to avoid exposure
glass cock; or a ground stopper, fitted with a small-bore cock
may be used with a ground-neck flask. to vapors and to prevent fire.
9.1.2 Allowthesolventtoevaporateinairatroomtempera-
7.1.3 Glass Balls,4to6-mmdiameter,thatshallnotbeable
to enter the bore of the cock. ture.
9.1.3 Cut the sample into small pieces (1 or 2 mm ) with
7.1.4 Mechanical Stirrer, to rotate the solution flask with a
uniform circular motion with a horizontal axis between 20 and scissors, using gloves to avoid touching the paper.
9.1.4 Keep the sample in a controlled-humidity atmosphere
40 r/min. The flask shall be mounted so that its axis is normal
to the axis of rotation, and the radius of gyration shall not be until it reaches equilibrium water content before removing the
material required for test purposes.
greater than 200 mm.
7.2 Apparatus for Measurement of Viscosity: 9.2 Nonimpregnated Papers:
7.2.1 Apparatus for Measurement of Kinematic Viscosity,as 9.2.1 Cut the sample into small pieces (1 or 2 mm ) with
described in Test Method D445. The viscometer shall have a scissors, using gloves to avoid touching the paper.
calibration constant, C, of from 0.00010 or 0.00013 St/s (10 3 9.2.2 Keep the sample in a controlled-humidity atmosphere
−9 −9 2 2
10 to 13 3 10 m /s ). until it reaches equilibrium water content before removing the
7.2.2 This constant shall be determined by measuring the material required for test purposes.
efflux-time T(seconds)ofaliquidofknowndynamicviscosity
2 3
10. Procedure
(Ns/m ) and density r (g/cm ). It is given by the formula:
10.1 Determination of Viscosity:
h
C 5 (1)
10.1.1 Test Specimen—Weigh to the nearest 0.1 mg an
r· T
amount (m) of paper, in equilibrium with the controlled
7.2.3 Constant-Temperature Water Bath, regulated at 20 6
atmosphere, of about:
0.1 °C.
10.1.1.1 125 mg when DP lies between 100 and 300,
v
7.2.4 Stopwatch, with an accuracy of 0.1 s.
10.1.1.2 50 mg when DP lies between 300 and 700, and
v
7.3 Apparatus for Measurement of Water Content of Paper
10.1.1.3 25 mg when DP lies between 700 and 1500.
v
Sample:
10.1.2 Solution:
7.3.1 Weighing Containers, impermeable to water vapor,
10.1.2.1 Put a few glass balls in the flask.
with airtight lids.
10.1.2.2 Add the weighed test specimen.
7.3.2 Ventilated Drying Oven, thermostatically controlled at
10.1.2.3 Carefully shake or stir by hand to ensure the small
105 6 2 °C.
pieces of paper are separated and evenly distributed.
7.3.3 Desiccator.
10.1.2.4 Add 22.5 mL of distilled water.
10.1.2.5 Again shake or stir by hand to disintegrate and wet
8. Reagents
all the paper completely.
8.1 Cupriethylene-Diamine Solution:
10.1.2.6 Leavefor ⁄2htoallowthoroughimpregnationwith
8.1.1 Theformulaascribedtocupriethylene-diamine(CED)
water.
is:
10.1.2.7 Add 22.5 mL of 1 M solution of cupriethylene-
@Cu~NH 2CH 2CH –NH ! #~OH! (2)
2 2 2 2 2 2
diamine.
This implies a molar ratio of 2 between the concentration of 10.1.2.8 Add a number of glass balls so that, when the
ethylene-diamine and the concentration of copper: stopper with capillary tube, and so forth, is fitted, the liquid
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D4243 – 99 (2004)
willentirelyfilltheflaskandreachtheboreofthecock.Donot
50 6
65 8
allow any pieces of paper to enter the capillary, for such paper
will not be dissolved.
10.2.2 Measurement of Water Content:
10.1.2.9 Close the cock.
10.2.2.1 After weighing, open the container and place it,
10.1.2.10 Allow the specimen to dissolve with mechanical
with the weighed test specimen and its cap, in the oven and
stirring as described in 7.1.4. The preferred solution time is 2
heat at 1056 2 °C until it reaches constant mass. This will
h; however, when the specimen is not satisfactorily dissolved,
normally require from 4 to 18 h.
the solution time may be increased to a maximum of 18 h. For
10.2.2.2 After drying, replace the cap on the container and
a specimen of an aged paper, there is little risk of further
allow it to cool in a desiccator for about 45 min.After cooling,
measurable degradation due to this increase of solution time.
equalize the air pressures inside and outside the container by
10.1.3 Measurement of Viscosity:
raising and lowering the cap quickly.Weigh the container with
10.1.3.1 After the period of stirring and before filling the
the specimen.
viscometer, allow the solution to stand for 1 h at the tempera-
10.2.3 Alternative procedures may be used to determine the
ture of measurement, 20 6 0.1 °C.
water content of the paper sample provided that it can be
10.1.3.2 Taketherequiredvolumeofsolutionandtransferit
verified that the procedure used will give results that differ
totheviscometerreservoir.Assembletheviscometerandplace
from the results used in 10.2.2 by no more than 0.5%.
the assembly in the thermostatic bath.
10.1.3.3 Wait 15 min before beginning the measurements.
11. Calculation
Then raise the liquid level above the upper mark of the
viscometer either by means of air pressure or slight vacuum. 11.1 Concentration, c, of Dry Paper in the Solution:
Measure the efflux time between the upper and lower marks.
11.1.1 The water content H of the paper, as a proportion of
Make three successive measurements. The difference between
the dry weight, is as follows:
the maximum and minimum time of flow shall be less than 0.5
H 5 ~M 2 M /M ! (5)
0 0
s. If this repeatability is not achieved, clean the viscometer as
described in 10.1.4. Take a second specimen of the solution
where:
that has been kept at the measurement temperature and make a M = mass of the test sample used for determining the
further series of three measurements. If again the difference is
water content before drying, g and
not less than 0.5 s, take a new specimen of paper and prepare M = mass of this sample after drying, g.
a fresh solution.
11.1.2 Knowing the mass, m, in grams of the test specimen
10.1.3.4 Under the same conditions, measure the flow time
anditswatercontent, H,theconcentration c(g/100mL),ofdry
of the solvent. This shall be between 90 and 110 s for the
paper in the solution is given by:
viscometer constant C stated in 6.2 (0.00010# C# 0.00013).
c 5 ~m·100/45!· ~1/1 1 H! (6)
10.1.4 Cleaning the Viscometer:
11.2 Specific Viscosity, h —The densities of the solvent and
10.1.4.1 By aspiration, fill the tube with chromic-acid mix- s
of the solution are practically identical. Thus, the specific
ture and immediately empty it again.
viscosity h as defined in 4.2 is given by:
s
10.1.4.2 Rinse thoroughly with distilled water.
10.1.4.3 Rinse twice with acetone or alcohol. T 2 T
s 0
h 5 (7)
s
T
10.1.4.4 Drybymeansofcompressedgasfromacylinderor 0
dust-and-oil-free compressed air.
where:
10.1.5 Make all tests in duplicate, making up two separate
T = mean efflux time of the solvent, and
solutions from separately weighed specimens.
T = mean efflux time of the solution.
s
10.2 Determination of Water Content of Paper:
11.3 Intrinsic Viscosity [h]:
10.2.1 Test Specimen:
11.3.1 The intrinsic viscosity is calculated using Martin’s
10.2.1.1 Weigh to the nearest milligram approximately 2 g
formula from the specific viscosity h and the concentration c
s
of paper in equilibrium with the controlled-humidity atmo-
(g/100 mL), of dry paper.
sphere, and in a closed weighing container that has been dried
11.3.2 As Martin’s formula does not readily lend itself to
and tared.
calculation of h, use Table 1, which contains values of the
10.2.1.2 If the paper sample is too small for2gtobe
product [h]· c as a function of [h ].
s
reserved for determining its water content, use a smaller
11.3.3 In Table 1, k = 0.14, which value has been found
specimen. However, if the amount of paper is only sufficient
experimentally for the operating conditions described.
for the viscometric measurements, its water content may be
deduced from the moisture equilibrium curves and the relative 11.4 Degree of Polymerization DP —The average visco-
v
metric degree of polymerization DP is given by the equation:
humidity of the conditioning atmosphere with which the paper
v
was in equilibrium. If equilibrium curves are not available for
a
DP 5[h]/K (8)
v
the particular paper tested, the following average values may
be used as a first approximation for temperatures between 20
where:
a
= 1, and
and 27 °C.
−3
K = 7.5 310 .
Relative Humidity of Air, % Water Content of Air, %
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D4243 – 99 (2004)
A
TABLE 1 Numerical Values of the Product [h]·Casa Function of [h ] According to Martin’s Formula (k = 0.14)
s
h· c
h 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09
s
0.0 0.010 0
...
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