ASTM D4243-99(2009)
(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 X1 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 ) 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-β-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 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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Designation: D4243 − 99 (Reapproved 2009)
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.
1. Scope 2.2 Other Document:
IEC60450MeasurementoftheAverageViscometricDegree
1.1 This test method describes a standard procedure for
of Polymerization of New and Aged Electrical Papers
determining the average viscometric degree of polymerization
¯
(abbreviated DP ) of new or aged electrical papers. The
3. Terminology
v
determination is made by measuring the intrinsic viscosity of a
3.1 Definitions—For definitions of terms used in this test
solution of the paper in an appropriate solvent.
method, refer to Terminology D1711.
1.2 The degree of polymerization (or the degree of conden-
4. Summary of Test Method
sation) of a particular cellulose molecule is the number of
anhydro-β-glucose monomers, C H O , in the cellulose mol-
4.1 This test method measures the specific viscosity of a
6 10 5
ecule.Withinasampleofpaper,notallthecellulosemolecules
solution of the paper in cupriethylene–diamine. From this
havethesamedegreeofpolymerizationsothatthemeanvalue
measurement the intrinsic viscosity of the solution is deduced,
measured by viscometric methods is not necessarily the same
andfromthisthedegreeofpolymerizationiseasilycalculated.
as that which may be obtained by other methods.
4.2 This test method follows very closely the procedures
1.3 This standard may involve hazardous materials,
specified in IEC 60450.
operations, and equipment. This standard does not purport to
5. Significance and Use
address all of the safety concerns, if any, associated with its
use. It is the responsibility of the user of this standard to 5.1 Thistestmethodmaybeappliedtoallpapersmadefrom
establish appropriate safety and health practices and to
unmodified cellulose, as used in transformer, cable, or capaci-
determine the applicability of regulatory limitations prior to tor manufacture. It applies to new or aged papers. For
use. See Section 9
information, Appendix X1 shows an example of statistical
¯
distribution of DP values for new papers intended for the
v
2. Referenced Documents
insulationoftransformers,togetherwithinformationrelativeto
2.1 ASTM Standards:
cable and capacitor papers. Nevertheless, where evaluating the
D445Test Method for Kinematic Viscosity of Transparent
decomposition stage of aged papers, take care to use, as a
and Opaque Liquids (and Calculation of DynamicViscos- ¯
reference, the DP value of the new paper of the very same
v
ity)
¯
origin; DP of new papers being a function, among other
v
D1711Terminology Relating to Electrical Insulation
factors, of their specific gravity and of their manufacturing
process.
5.2 This test method can also be used for the determination
of the intrinsic viscosity of solutions of chemically modified
papers,providedthatthesedissolvecompletelyintheselection
solvent. This test method should be used with caution when it
This test method is under the jurisdiction of ASTM Committee D09 on
is applied to papers with mineral fillers.
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.01 on Electrical Insulating Products.
6. Interferences
Current edition approved Oct. 1, 2009. Published February 2010. Originally
ε1
approved in 1983. Last previous edition approved in 2004 as D4243–99(2004) .
6.1 Lignins, that are present in measurable amounts in most
DOI: 10.1520/D4243-99R09.
papers and boards, may have an effect on the test results,
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 fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4243 − 99 (2009)
depending upon concentration and composition. For this trationgreaterthan1 Mitmaybekeptforoneyearinthedark.
reason, it is important in aging studies to use as a reference It is diluted to 1 M when required for use. Alternatively the
samples of the unaged paper as mentioned in 5.1. CED solution can be made in the laboratory at its working
strength of 1 M by the methods described in Annex A1.
6.2 Under some conditions of heat and atmosphere, cross
8.1.3 The 1 M solution will keep only for a limited time.As
linking of cellulose molecules may occur, resulting in erratic
often as necessary the solution should be checked by:
testvalues.Thiseffecthasbeenobservedforcapacitortissuein
8.1.3.1 Using the method described in Annex A2 to verify
vacuum at temperatures as low as 110°C and for other papers
that the ratio
aged in air at higher temperatures.
C /C 5 2.060.1. (4)
ED Cu
7. Apparatus
8.1.3.2 Verifythatthereisnoprecipitateinthesolution.Any
7.1 Apparatus for Solution:
precipitate should be removed by filtering or by decanting.
7.1.1 Round-Bottomed 50-mL Flask, preferably with a short
narrow neck, or a narrow-necked 50-mL Erlenmeyer flask.
9. Preparation of Specimens
7.1.2 Rubber Stopper, fitting the neck of the flask, through
9.1 Impregnated Papers:
which passes a capillary tube fitted with a small-bore cock
9.1.1 Using a Soxhlet extractor, degrease the paper with
glass cock; or a ground stopper, fitted with a small-bore cock
hexane or, if necessary, with chloroform. (Warning—
may be used with a ground-neck flask.
Chloroform is toxic, and hexane is flammable. Adequate
7.1.3 Glass Balls,4to6-mmdiameter,thatshallnotbeable
precautions must be taken to avoid exposure to vapors and to
to enter the bore of the cock.
prevent fire.)
7.1.4 Mechanical Stirrer, to rotate the solution flask with a
9.1.2 Allowthesolventtoevaporateinairatroomtempera-
uniform circular motion with a horizontal axis between 20 and
ture.
40 r/min. The flask shall be mounted so that its axis is normal
9.1.3 Cut the sample into small pieces (1 or 2 mm ) with
to the axis of rotation, and the radius of gyration shall not be
scissors, using gloves to avoid touching the paper.
greater than 200 mm.
9.1.4 Keep the sample in a controlled-humidity atmosphere
7.2 Apparatus for Measurement of Viscosity:
until it reaches equilibrium water content before removing the
7.2.1 Apparatus for Measurement of Kinematic Viscosity, as
material required for test purposes.
described in Test Method D445. The viscometer shall have a
9.2 Nonimpregnated Papers:
calibration constant, C, of from 0.00010 or 0.00013 St/s (10 ×
−9 −9 2 2 2
9.2.1 Cut the sample into small pieces (1 or 2 mm ) with
10 to 13 × 10 m /s ).
scissors, using gloves to avoid touching the paper.
7.2.2 This constant shall be determined by measuring the
9.2.2 Keep the sample in a controlled-humidity atmosphere
efflux-time T(seconds)ofaliquidofknowndynamicviscosity
2 3
(Ns/m ) and density ρ (g/cm ). It is given by the formula: until it reaches equilibrium water content before removing the
material required for test purposes.
η
C 5 (1)
ρ·T
10. Procedure
7.2.3 Constant-Temperature Water Bath, regulated at 20 6
10.1 Determination of Viscosity :
0.1°C.
10.1.1 Test Specimen—Weigh to the nearest 0.1 mg an
7.2.4 Stopwatch, with an accuracy of 0.1 s.
amount (m) of paper, in equilibrium with the controlled
7.3 Apparatus for Measurement of Water Content of Paper
atmosphere, of about:
Sample:
¯
10.1.1.1 125 mg whenDP lies between 100 and 300,
v
7.3.1 Weighing Containers, impermeable to water vapor,
¯
10.1.1.2 50 mg when DP lies between 300 and 700, and
v
with airtight lids.
7.3.2 Ventilated Drying Oven, thermostatically controlled at ¯
10.1.1.3 25 mg whenDP lies between 700 and 1500.
v
105 6 2°C.
10.1.2 Solution:
7.3.3 Desiccator.
10.1.2.1 Put a few glass balls in the flask.
10.1.2.2 Add the weighed test specimen.
8. Reagents
10.1.2.3 Carefully shake or stir by hand to ensure the small
8.1 Cupriethylene-Diamine Solution:
pieces of paper are separated and evenly distributed.
8.1.1 Theformulaascribedtocupriethylene-diamine(CED)
10.1.2.4 Add 22.5 mL of distilled water.
is:
10.1.2.5 Again shake or stir by hand to disintegrate and wet
@Cu NH 2 CH 2 CH 2 NH # OH (2)
~ ! ~ !
2 2 2 2 all the paper completely.
2 2
10.1.2.6 Leavefor ⁄2htoallowthoroughimpregnationwith
This implies a molar ratio of 2 between the concentration of
water.
ethylene-diamine and the concentration of copper:
10.1.2.7 Add 22.5 mL of 1 M solution of cupriethylene-
~C /C ! 52 (3)
ED cu
diamine.
8.1.2 Cupriethylene-diamine solution may be purchased 10.1.2.8 Add a number of glass balls so that, when the
commercially at several different concentrations.At a concen- stopper with capillary tube, and so forth, is fitted, the liquid
D4243 − 99 (2009)
willentirelyfilltheflaskandreachtheboreofthecock.Donot
Relative Humidity of Air, % Water Content of Air, %
50 6
allow any pieces of paper to enter the capillary, for such paper
65 8
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 105 6 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.
11. Calculation
10.1.3.3 Wait 15 min before beginning the measurements.
Then raise the liquid level above the upper mark of the 11.1 Concentration, c, of Dry Paper in the Solution:
viscometer either by means of air pressure or slight vacuum. 11.1.1 The water content H of the paper, as a proportion of
Measure the efflux time between the upper and lower marks. the dry weight, is as follows:
Make three successive measurements. The difference between
H 5 M 2 M /M (5)
~ !
0 0
the maximum and minimum time of flow shall be less than 0.5
where:
s. If this repeatability is not achieved, clean the viscometer as
described in 10.1.4. Take a second specimen of the solution M = mass of the test sample used for determining the water
that has been kept at the measurement temperature and make a content before drying, g and
M = mass of this sample after drying, g.
further series of three measurements. If again the difference is
not less than 0.5 s, take a new specimen of paper and prepare
11.1.2 Knowing the mass, m, in grams of the test specimen
a fresh solution.
anditswatercontent, H,theconcentration c(g/100mL),ofdry
10.1.3.4 Under the same conditions, measure the flow time
paper in the solution is given by:
of the solvent. This shall be between 90 and 110 s for the
c 5 ~m·100/45!·~1/11H! (6)
viscometer constant C stated in 6.2 (0.00010 ≤ C ≤ 0.00013).
11.2 Specific Viscosity, η —The densities of the solvent and
s
10.1.4 Cleaning the Viscometer:
of the solution are practically identical. Thus, the specific
10.1.4.1 By aspiration, fill the tube with chromic-acid mix-
viscosity η as defined in 4.2 is given by:
s
ture and immediately empty it again.
T 2 T
10.1.4.2 Rinse thoroughly with distilled water. s 0
η 5 (7)
s
T
10.1.4.3 Rinse twice with acetone or alcohol.
10.1.4.4 Drybymeansofcompressedgasfromacylinderor
where:
dust-and-oil-free compressed air.
T = mean efflux time of the solvent, and
10.1.5 Make all tests in duplicate, making up two separate
T = mean efflux time of the solution.
s
solutions from separately weighed specimens.
11.3 Intrinsic Viscosity [η]:
10.2 Determination of Water Content of Paper: 11.3.1 The intrinsic viscosity is calculated using Martin’s
formula from the specific viscosity η and the concentration c
10.2.1 Test Specimen:
s
(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
calculation of η, use Table 1, which contains values of the
atmosphere, and in a closed weighing container that has been
product [η]· c as a function of [η ].
dried and tared. s
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
¯
specimen. However, if the amount of paper is only sufficient
11.4 Degree of Polymerization DP —The average viscomet-
v
for the viscometric measurements, its water content may be ¯
ric degree of polymerization DP is given by the equation:
v
deduced from the moisture equilibrium curves and the relative
¯ α
humidity of the conditioning atmosphere with which the paper DP 5 @η#/K (8)
v
was in equilibrium. If equilibrium curves are not available for
where:
the particular paper tested, the following average values may
α
= 1, and
be used as a first approximation for temperatures between 20
−3
K = 7.5×10 .
and 27°C.
D4243 − 99 (2009)
A
TABLE 1 Numerical Values of the Product [η]·Casa Function of [η ] According to Martin’s Formula (k = 0.14)
s
η· c
η 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 0.020 0.030 0.039 0.049 0.059 0.068 0.078 0.087
0.1 0.097 0.106 0.116 0.125 0.134 0.143 0.152 0.161 0.170 0.179
0.2 0.188 0.197 0.206 0.215
...
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