ASTM D4243-99
(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
SCOPE
1.1 This 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-[beta]-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.
1.3 This standard does not purport to address all of the safety problems, 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.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
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An American National Standard
Designation: D 4243 – 99
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method describes a standard procedure for 3.1 Definitions—For definitions of terms used in this test
determining the average viscometric degree of polymerization method, refer to Terminology D1711.
(abbreviated DP ) of new or aged electrical papers. The
v
4. Summary of Test Method
determination is made by measuring the intrinsic viscosity of a
solution of the paper in an appropriate solvent. 4.1 This test method measures the specific viscosity of a
solution of the paper in cupriethylene–diamine. From this
1.2 The degree of polymerization (or the degree of conden-
sation) of a particular cellulose molecule is the number of measurement the intrinsic viscosity of the solution is deduced,
and from this the degree of polymerization is easily calculated.
anhydro-b-glucose monomers, C H O , in the cellulose mol-
6 10 5
ecule.Withinasampleofpaper,notallthecellulosemolecules 4.2 This test method follows very closely the procedures
specified in IEC Publication 450.
have the same degree of polymerization so that the mean value
measured by viscometric methods is not necessarily the same
5. Significance and Use
as that which may be obtained by other methods.
5.1 Thistestmethodmaybeappliedtoallpapersmadefrom
1.3 This standard may involve hazardous materials, opera-
unmodified cellulose, as used in transformer, cable, or capaci-
tions, and equipment. This standard does not purport to
tor manufacture. It applies to new or aged papers. For
address all of the safety concerns, if any, associated with its
information, Appendix X2 shows an example of statistical
use. It is the responsibility of the user of this standard to
distribution of DP values for new papers intended for the
establish appropriate safety and health practices and to
v
insulationoftransformers,togetherwithinformationrelativeto
determine the applicability of regulatory limitations prior to
cable and capacitor papers. Nevertheless, where evaluating the
use. See Section 9
decomposition stage of aged papers, take care to use, as a
2. Referenced Documents
reference, the DP value of the new paper of the very same
v
origin; DP of new papers being a function, among other
2.1 ASTM Standards:
v
D445 Test Method for Kinematic Viscosity of Transparent factors, of their specific gravity and of their manufacturing
process.
and Opaque Liquids (the Calculation of Dynamic Viscos-
ity) 5.2 This test method can also be used for the determination
of the intrinsic viscosity of solutions of chemically modified
D1711 Terminology Relating to Electrical Insulation
2.2 Other Document: papers,providedthatthesedissolvecompletelyintheselection
solvent. This test method should be used with caution when it
IEC Publication 450 Measurement of the Average Visco-
metric Degree of Polymerization of New and Aged is applied to papers with mineral fillers.
Electrical Papers
6. Interferences
6.1 Lignins, that are present in measurable amounts in most
This test method is under the jurisdiction of ASTM Committee D-9 on
papers and boards, may have an effect on the test results,
Electrical and Electronic Insulating Materials and is the direct responsibility of
depending upon concentration and composition. For this rea-
Subcommittee D09.19 on Dielectric Sheet and Roll Products.
son, it is important in aging studies to use as a reference
Current edition approved April 10, 1999. Published June 1999. Originally
published as D4243–83. Last previous edition D4243–86 (1998).
samples of the unaged paper as mentioned in 5.1.
Annual Book of ASTM Standards, Vol 10.03.
6.2 Under some conditions of heat and atmosphere, cross
Annual Book of ASTM Standards, Vol 10.01.
4 linking of cellulose molecules may occur, resulting in erratic
Available from American National Standards Institute, 11 W. 42nd St., 13th
Floor, New York, NY 10036. testvalues.Thiseffecthasbeenobservedforcapacitortissuein
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D4243–99
C /C 52.0 60.1. (4)
vacuum at temperatures as low as 110°C and for other papers
ED Cu
aged in air at higher temperatures.
8.1.3.2 Verifythatthereisnoprecipitateinthesolution.Any
precipitate should be removed by filtering or by decanting.
7. Apparatus
7.1 Apparatus for Solution:
9. Preparation of Specimens
7.1.1 Round-Bottomed 50-mL Flask, preferably with a short
9.1 Impregnated Papers:
narrow neck, or a narrow-necked 50-mL Erlenmeyer flask.
9.1.1 Using a Soxhlet extractor, degrease the paper with
7.1.2 Rubber Stopper, fitting the neck of the flask, through
hexane or, if necessary, with chloroform.
which passes a capillary tube fitted with a small-bore cock
9.1.1.1 Caution—Chloroform is toxic, and hexane is flam-
glass cock; or a ground stopper, fitted with a small-bore cock
mable.Adequate precautions must be taken to avoid exposure
may be used with a ground-neck flask.
to vapors and to prevent fire.
7.1.3 Glass Balls,4to6-mmdiameter,thatshallnotbeable
9.1.2 Allowthesolventtoevaporateinairatroomtempera-
to enter the bore of the cock.
ture.
7.1.4 Mechanical Stirrer, to rotate the solution flask with a
9.1.3 Cut the sample into small pieces (1 or 2 mm ) with
uniform circular motion with a horizontal axis between 20 and
scissors, using gloves to avoid touching the paper.
40 r/min. The flask shall be mounted so that its axis is normal
9.1.4 Keep the sample in a controlled-humidity atmosphere
to the axis of rotation, and the radius of gyration shall not be
until it reaches equilibrium water content before removing the
greater than 200 mm.
material required for test purposes.
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
(Ns/m ) and density r (g/cm ). It is given by the formula:
10. Procedure
h
10.1 Determination of Viscosity:
C 5 (1)
r· T
10.1.1 Test Specimen—Weigh to the nearest 0.1 mg an
7.2.3 Constant-Temperature Water Bath, regulated at 20 6
amount (m) of paper, in equilibrium with the controlled
0.1°C.
atmosphere, of about:
7.2.4 Stopwatch, with an accuracy of 0.1 s.
10.1.1.1 125 mg when DP lies between 100 and 300,
v
7.3 Apparatus for Measurement of Water Content of Paper
10.1.1.2 50 mg when DP lies between 300 and 700, and
v
Sample:
10.1.1.3 25 mg when DP lies between 700 and 1500.
v
7.3.1 Weighing Containers, impermeable to water vapor,
10.1.2 Solution:
with airtight lids.
10.1.2.1 Put a few glass balls in the flask.
7.3.2 Ventilated Drying Oven, thermostatically controlled at
10.1.2.2 Add the weighed test specimen.
105 6 2°C.
10.1.2.3 Carefully shake or stir by hand to ensure the small
7.3.3 Desiccator.
pieces of paper are separated and evenly distributed.
10.1.2.4 Add 22.5 mL of distilled water.
8. Reagents
10.1.2.5 Again shake or stir by hand to disintegrate and wet
8.1 Cupriethylene-Diamine Solution:
all the paper completely.
8.1.1 Theformulaascribedtocupriethylene-diamine(CED)
10.1.2.6 Leavefor ⁄2htoallowthoroughimpregnationwith
is:
water.
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
~C /C ! 52 (3)
ED cu
willentirelyfilltheflaskandreachtheboreofthecock.Donot
8.1.2 Cupriethylene-diamine solution may be purchased allow any pieces of paper to enter the capillary, for such paper
commercially at several different concentrations.At a concen- will not be dissolved.
trationgreaterthan1 Mitmaybekeptforoneyearinthedark. 10.1.2.9 Close the cock.
It is diluted to 1 M when required for use. Alternatively the 10.1.2.10 Allow the specimen to dissolve with mechanical
CED solution can be made in the laboratory at its working stirring as described in 7.1.4. The preferred solution time is 2
strength of 1 M by the methods described in Annex A1. h; however, when the specimen is not satisfactorily dissolved,
8.1.3 The 1 M solution will keep only for a limited time.As the solution time may be increased to a maximum of 18 h. For
often as necessary the solution should be checked by: a specimen of an aged paper, there is little risk of further
measurable degradation due to this increase of solution time.
8.1.3.1 Using the method described in Annex A2 to verify
that the ratio 10.1.3 Measurement of Viscosity:
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
D4243–99
10.1.3.1 After the period of stirring and before filling the 10.2.3 Alternative procedures may be used to determine the
viscometer, allow the solution to stand for 1 h at the tempera- water content of the paper sample provided that it can be
ture of measurement, 20 6 0.1°C. verified that the procedure used will give results that differ
10.1.3.2 Taketherequiredvolumeofsolutionandtransferit from the results used in 10.2.2 by no more than 0.5%.
totheviscometerreservoir.Assembletheviscometerandplace
11. Calculation
the assembly in the thermostatic bath.
11.1 Concentration, c, of Dry Paper in the Solution:
10.1.3.3 Wait 15 min before beginning the measurements.
11.1.1 The water content H of the paper, as a proportion of
Then raise the liquid level above the upper mark of the
the dry weight, is as follows:
viscometer either by means of air pressure or slight vacuum.
Measure the efflux time between the upper and lower marks.
H 5 ~M 2 M /M ! (5)
0 0
Make three successive measurements. The difference between
where:
the maximum and minimum time of flow shall be less than 0.5
M = mass of the test sample used for determining the
s. If this repeatability is not achieved, clean the viscometer as
water content before drying, g and
described in 10.1.4. Take a second specimen of the solution
M = mass of this sample after drying, g.
that has been kept at the measurement temperature and make a
11.1.2 Knowing the mass, m, in grams of the test specimen
further series of three measurements. If again the difference is
anditswatercontent, H,theconcentration c(g/100mL),ofdry
not less than 0.5 s, take a new specimen of paper and prepare
paper in the solution is given by:
a fresh solution.
10.1.3.4 Under the same conditions, measure the flow time c 5 ~m·100/45!· ~1/1 1 H! (6)
of the solvent. This shall be between 90 and 110 s for the
11.2 Specific Viscosity, h —The densities of the solvent and
s
viscometer constant C stated in 6.2 (0.00010# C# 0.00013).
of the solution are practically identical. Thus, the specific
10.1.4 Cleaning the Viscometer:
viscosity h as defined in 4.2 is given by:
s
10.1.4.1 By aspiration, fill the tube with chromic-acid mix-
T 2 T
s 0
ture and immediately empty it again.
h 5 (7)
s
T
10.1.4.2 Rinse thoroughly with distilled water.
10.1.4.3 Rinse twice with acetone or alcohol.
where:
10.1.4.4 Drybymeansofcompressedgasfromacylinderor T = mean efflux time of the solvent, and
dust-and-oil-free compressed air. T = mean efflux time of the solution.
s
10.1.5 Make all tests in duplicate, making up two separate 11.3 Intrinsic Viscosity [h]:
solutions from separately weighed specimens. 11.3.1 The intrinsic viscosity is calculated using Martin’s
10.2 Determination of Water Content of Paper: formula from the specific viscosity h and the concentration c
s
10.2.1 Test Specimen: (g/100 mL), of dry paper.
10.2.1.1 Weigh to the nearest milligram approximately 2 g 11.3.2 As Martin’s formula does not readily lend itself to
of paper in equilibrium with the controlled-humidity atmo- calculation of h, use Table 1, which contains values of the
sphere, and in a closed weighing container that has been dried
product [h]· c as a function of [h ].
s
and tared. 11.3.3 In Table 1, k = 0.14, which value has been found
10.2.1.2 If the paper sample is too small for2gtobe
experimentally for the operating conditions described.
reserved for determining its water content, use a smaller 11.4 Degree of Polymerization DP —The average visco-
v
specimen. However, if the amount of paper is only sufficient
metric degree of polymerization DP is given by the equation:
v
for the viscometric measurements, its water content may be
a
DP 5[h]/K (8)
v
deduced from the moisture equilibrium curves and the relative
humidity of the conditioning atmosphere with which the paper
where:
a
was in equilibrium. If equilibrium curves are not available for
= 1, and
−3
K = 7.5 310 .
the particular paper tested, the following average values may
be used as a first approximation for temperatures between 20
12. Validity of Results
and 27°C.
12.1 Two conditions should be met if the results are to be
Relative Humidity of Air, % Water Content of Air, %
50 6 considered significant:
65 8
12.1.1 Both values DP should agree within 2.5% of their
v
10.2.2 Measurement of Water Content: mean value.
10.2.2.1 After weighing, open the container and place it, 12.1.2 After measuring the viscosity, filter the solution
with the weighed test specimen and its cap, in the oven and through a fine-sintered glass filter; wash the filter and any
heat at 1056 2°C until it reaches constant mass. This will deposit with hydrochloric acid (diluted with one part water to
normally require from 4 to 18 h. three parts acid), then with distilled water; dry in an oven of
10.2.2.2 After drying, replace the cap on the container and about 110°C, allow to cool in a desiccator, a
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