ASTM D1795-96(2001)e1
(Test Method)Standard Test Method for Intrinsic Viscosity of Cellulose
Standard Test Method for Intrinsic Viscosity of Cellulose
SCOPE
1.1 This test method covers the determination of the intrinsic viscosity of purified celluloses such as bleached wood pulps, cotton linters, and regenerated cellulose. It is applicable to all cellulose samples with an intrinsic viscosity of 15 dl/g or less. Most native (unpurified) celluloses have intrinsic viscosity values too high for measurement by this test method.
Note 1—The use of cuprammonium hydroxide solution for regular viscosity determination is described in Method T 206 m-55 of the Technical Association of Pulp and Paper Industry on "Cuprammonium Disperse Viscosity of Pulp," and Joint Army-Navy Specifications JAN-C-206.
1.2 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 determine the applicability of regulatory limitations prior to use.
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e1
Designation: D 1795 – 96 (Reapproved 2001)
Standard Test Method for
Intrinsic Viscosity of Cellulose
This standard is issued under the fixed designation D1795; 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.
e NOTE—Editorial changes were made throughout in August 2001.
1. Scope 4. Significance and Use
1.1 This test method covers the determination of the intrin- 4.1 This test is a sensitive measure of the degradation of
sic viscosity of purified celluloses such as bleached wood celluloseresultingfromtheactionofheat,light,acids,alkalies,
pulps, cotton linters, and regenerated cellulose. It is applicable oxidizing and reducing agents, and the like, used in its
to all cellulose samples with an intrinsic viscosity of 15 dl/g or processingorpurification.Theintrinsicviscosityvaluemaybe
less. Most native (unpurified) celluloses have intrinsic viscos- converted to degree of polymerization (DP) or to intrinsic
ity values too high for measurement by this test method. fluidity, if desired.
4.2 SolutionsofcellulosearenotNewtonianliquids;thatis,
NOTE 1—The use of cuprammonium hydroxide solution for regular
their viscosity depends upon the rate-of-shear or velocity
viscosity determination is described in Method T206 m-55 of the
gradientduringmeasurement.Thiseffectissmallerforsamples
Technical Association of Pulp and Paper Industry on “Cuprammonium
Disperse Viscosity of Pulp,” and Joint Army-Navy Specifications JAN- oflowmolecularmass(DP)andatlowconcentrationsthanfor
C-206.
high-DPsamplesandathighconcentrations.Forthecelluloses
and concentrations included within the limits set forth in this
1.2 This standard does not purport to address all of the
test method, the effect of rate-of-shear is assumed to be
safety concerns, if any, associated with its use. It is the
negligible for referee purposes. For other conditions and for
responsibility of the user of this standard to establish appro-
research purposes this assumption may be invalid, but to
priate safety and health practices and determine the applica-
discuss ways of accounting for this effect is beyond the scope
bility of regulatory limitations prior to use.
of the present test method.
2. Referenced Documents
5. Apparatus
2.1 ASTM Standards:
5.1 Viscometer, Glass, Capillary Type— The Cannon-
D445 Test Method for Kinematic Viscosity of Transparent
Fenske, Ubbelohde, or similar capillary type instrument as
and Opaque Liquids (and the Calculation of Dynamic
described in Test Method D445 is recommended. In order to
Viscosity)
avoidcorrectionforthekineticenergyeffect,chooseaviscom-
D629 Test Methods for Quantitative Analysis of Textiles
eterwithasmallenoughcapillarytogiveanoutflowtimeof80
E1 Specification for ASTM Thermometers
s or more for the Cannon-Fenske type. (Asize 100 viscometer
3. Summary of Test Method
is normally used for the sample solution and a size 50 for the
solvent.)
3.1 Aweighedsampleofthematerialisdissolvedina0.5M
5.2 Thermometer—ASTM Kinematic Viscosity Thermom-
cupriethylenediamine hydroxide solution. The viscosity of this
eter for use at 25°C, having a range from 19 to 27°C and
solution, and also that of the solvent, is determined at 25°C by
conforming to the requirement for Thermometer 17C as
means of a calibrated glass capillary-type viscometer. The
prescribed in Specification E1.
relative viscosity is calculated and the corresponding intrinsic
5.3 Bath—Aconstant-temperature bath at 25°C suitable for
viscosity is read from a table.
immersion of the viscometer so that the reservoir or the top of
the capillary, whichever is uppermost, is immersed at least 50
This test method is under the jurisdiction of ASTM Committee D01 on Paint
mm, and with provision for visibility of the instrument and the
and Related Coatings, Materials, andApplications and is the direct responsibility of
thermometer. Firm supports for the viscometer shall be pro-
Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
vided; or the viscometer may be sealed in as an integral part of
Current edition approved Nov. 10, 1996. Published January 1997. Originally
published as D1795 – 60. Last previous edition D1795–94.
the bath. Either a liquid bath with thermostatic regulation and
Annual Book of ASTM Standards, Vol 05.01.
astirreroravaporbathwithpressureregulationispermissible.
Annual Book of ASTM Standards, Vol 07.01.
The efficiency of the stirring and the balance between heat
Annual Book of ASTM Standards, Vol 14.03.
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D 1795
NOTE 3—Detailed specifications and directions for filling, calibrating,
losses and heat input must be such that the temperature of the
and measurement with types of capillary viscometers most used are given
bath medium does not vary by more than 60.1°C over the
in Test Method D445.
length of the viscometer, or from viscometer to viscometer in
NOTE 4—Calibrationoftheviscometersmaybeavoidedifbothsolvent
the various bath positions. If a vapor bath is used, there must
and solution are measured in the same instrument. Then the relative
be no temperature gradient over the length of the viscometer
viscosity is nearly the ratio of outflow times for solution and solvent,
greater than that permitted in a liquid bath.
respectively. This simplification involves two assumptions. The first, that
5.4 Timer—A stop watch or other spring-activated timing
the densities of solution and solvent are equal, holds very well for the
device or electrical timing device shall be used, graduated in dilute solutions used in these tests. The second, that the kinetic energy
correction is zero, depends upon the choice of viscometer. If the one used
divisions of 0.2 s or less, and accurate to within 0.05% when
gives convenient outflow times for the solution of less than 150 s, then it
tested over not less than a 10-min period. Such electrical
will be too fast for the solvent. The kinetic energy correction is zero,
timing devices shall be used only on electrical circuits of
depending upon flow. On the other hand, if one is chosen so that the
continuously controlled frequency. Frequency-controlled de-
outflow time for the solvent is large enough (80 s or more), then the times
vices of suitable capacity for laboratory purposes, accurate to
for the solutions will in most cases be inconveniently long. For some
within 1 part in 10 000 should be used. Errors exceeding
work, however, it may be desirable to make some sacrifice in accuracy or
0.05% of a 10-min interval may occur in timing devices in convenience during measurement in order to avoid calibration and
using two sizes of viscometers.
actuated by electrical synchronous motors driven by most
public power systems, which are intermittently and not con-
8.2 Bymeansofapipet,add7.0mLofthecalibratingliquid
tinuously controlled.
totheviscometer,inaconstant-temperaturebathat25 60.1°C
(or fill as described in Test Method D445, Appendix A).
6. Reagent
8.3 When the liquid has reached temperature equilibrium
6.1 CupriethylenediamineHydroxideSolution (1.00 60.01
with the bath (in about 5 min), determine the outflow time t by
M), in copper, with the molar ratio of ethylenediamine to
drawingthetopmeniscusoftheliquidabovethemarkbetween
copper of 2 6 0.1 to 1. This solvent may be prepared in the
thetwobulbsandmeasuringthetimerequiredforthemeniscus
laboratory. It is also commercially available.
to pass from this mark to the mark below the lower bulb. Take
the average of two or more observations, which should differ
7. Reference Materials
by not more than 0.2 s.
7.1 Viscosity Oil Standards—Calibrating oils in the speci-
8.4 Determine the viscometer constant C by the equation:
fiedrangesofviscosity. Aqueoussolutionsofglycerolmaybe
C5h/dt (1)
used instead of standardized oils; the compositions for various
viscosities are given in chemical handbooks. The applicable
where:
viscosity oil standards (Note 2) are listed in Table 1.
h = viscosity of the calibrating liquid, cP,
d = density, g/mL, and
t = time, s.
TABLE 1 Viscosity Oil Standards
Viscometer Viscosity Oil Standard
9. Preparation of Sample
Approximate
Absolute Viscosity
Size Designation Absolute Viscosity
A
Range, cP
9.1 To avoid undesirable effects from long heating at high
at 77°F (25°C), cP
50 0.9to3.5 S-3 3.3
temperature, samples should be air-dried and the moisture
100 3.3 to 13.3 S-6 7.7
content determined on a portion that is not used for measure-
A
For solution with density of 0.9.
ment of viscosity. The mass of air-dried samples is then
corrected for moisture to obtain the mass of oven-dried
cellulose used to calculate concentration.
NOTE 2—The viscosity oil standards are available only as 1-pt (4.7- m
3) samples. More than 1 pt of any given oil (for example, duplicate 9.2 Soft, sheeted pulp should be picked apart with tweezers
samples) are supplied only when it is established that 1 pt is inadequate.
orscrapedwithadullknife.Hard-pressedorharshpulpshould
be slurried in water, formed into thin sheets on a Büchner
8. Calibration of Viscometer
funnel, and dried at a temperature below 100°C (preferably
8.1 The following directions apply to the Cannon-Fenske
roomtemperature).Loosepulpshouldbepickedapartbyhand
viscometer (Note 3).They should be modified according to the
to break up any lumps. Slurried or slush pulps should be
operating instructions for other types of viscometers. The
formed into thin sheets and dried. Yarn and staple should be
viscometers shall be calibrated (Note 4) by means of liquids
washed in warm water containing a little detergent to remove
having known viscosities approximately equal to those of the
the finish, rinsed thoroughly, dried (at low temperature), and
solvent and cellulose solutions respectively (1.2 and 12 cP,
fluffed.(Itwillbefoundhelpfultocutyarnandlongstapleinto
approximately). 1
short lengths, say ⁄2 in. (13 mm), before washing.) Fabrics
should be cut into small pieces, desized (see Test Methods
D629,Section8),thoroughlywashed,anddried.Ravelingwill
Thesolesourceofsupplyoftheviscosityoilstandardsknowntothecommittee
be helpful before dissolving samples that tend to get in the
atthistimeisCannonInstrumentCo.,P.O.Box16,StateCollege,PA16801.Ifyou
solvent. Materials containing a considerable amount of non-
are aware of alternative suppliers, please provide this information to ASTM
cellulosic matter must first be purified; such treatments lie
Headquarters.Your comments will receive careful consideration at a meeting of the
responsible technical committee, which you may attend. outside the scope of this test method.
D 1795
TABLE 2 Intrinsic Viscosities of Typical Samples cotton linters with degree of polymerization (DP) as low as that of wood
pulps.Thedifficultyshowsupbymuchpoorerprecisionofresultsthanthe
Intrinsic Approximate
1 to 2% that is normally obtained between measurements made with two
Type of Material Viscosity, Concentration,
dL/g g/dL ormoresolutionsofthesamesample.Evensolutionsthatleavenoresidue
on fritted-glass filters have been observed to give erratic results. Inad-
Regenerated cellulose (rayons) 2 to 3 1
equate dispersion of the sample is apparently the cause, and two
Dissolving pulps:
Low viscosity 3 to 4 1 modifications in procedure have been recommended in such cases. One is
Regular viscosity 4 to 7 0.5
to add about 0.04% wetting agent to the water used to wet out the
High viscosity 7 to 10 0.3 6
sample. The other requires use of cupriethylenediamine solutions of two
Cotton linters, for rayon and acetate 6 to 9 0.4
concentrations:Thesampleiswettedoutwithonesolutionthatis0.167M
Paper (wood) pulps 3 to 8 0.4
A in copper and dispersion is completed by adding the second solution,
Native celluloses 15 to 30 0.1 to 0.2
1.000 M in copper, in such volume as to make the final copper
A
Seriouserrormaybeintroducedwhenthistestmethod,whichneglectseffects
concentration 0.500 M.
of rate of shear upon viscosity, is used for native celluloses of high intrinsic
viscosity.
11. Measurement of Viscosity
11.1 Transfer 7.0 mL of the solution by means of a syringe
10. Preparation of Solution
or pipet to a viscometer previously placed in the bath at 25°C
10.1 The sample size is dependent upon the nature of the
and flushed with nitrogen (or fill as described in Test Method
material,smallermassesofhigh-viscositycellulosesandlarger
D445, Appendix A). Allow at least 5 min for the solution to
masses of low-viscosity celluloses being used in order to keep
reach bath temperature.
the viscosity of the solutions within rather narrow limits.
11.2 By applying either pressure (with nitrogen) or suction,
(Working at nearly constant viscosity reduces the effect of rate
drawthesolutionintothelowerbulboftheviscometeruntilthe
of shear upon the measurements.) The concentration for each
top meniscus is a little above the mark between the two bulbs.
sample is chosen according to the rule:
Measure the time t required for the meniscus to pass from this
@h#c 53.09 60.5 (2)
mark to the mark below the lower bulb. Repeat at least twice
and average the observations, which should not differ by more
where:
than 0.3%.
[h] = intrinsic viscosity, dL/g, and
11.3 In the same way, measure the outflow time t for the
c = cellulose concentration, g/dL.
solvent. This of course must be determined not for the 1.00 M
Obviously, use of this rule requires knowledge of the
solvent as prepared or purchased, but for this solvent diluted
approximate intrinsic viscosity of the sample before the con-
with an equal volume of water.
centration can be estimated. In routine control work, such
information is available. If it is not, Table 2 will serve as an
12. Calculations
approximate guide.
12.1 Calculate the viscosity, h, in centipoises, as follows:
10.2 Make up a preliminary solution of about the indicated
concentration, and determine the viscosity as described in
h5 Ctd (3)
Sections 11 and 12. From the relative viscosity thus obtained,
where:
find the approximate value of the intrinsic viscosity by means
C = viscometer constant (Section 8),
of Table 3. From this determine the concentration needed to
t = outflow time, s, and
give: [h] c=3.0. If this preliminary solution does not give a
d = density, g/mL.
value of [h]c of 3.0 6 0.5, prepare a second solution of the
Calculate the relative viscosity, h , as follows:
rel
indicated concentration for the final viscosity measurement.
h 5h/h
10.3 Alkaline solutions of cellulose are known to be sensi- rel 0
tive to oxidation. Hence it is usually necessary to exc
...
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