ASTM D1795-96(2007)e1
(Test Method)Standard Test Method for Intrinsic Viscosity of Cellulose
Standard Test Method for Intrinsic Viscosity of Cellulose
SIGNIFICANCE AND USE
This test is a sensitive measure of the degradation of cellulose resulting from the action of heat, light, acids, alkalies, oxidizing and reducing agents, and the like, used in its processing or purification. The intrinsic viscosity value may be converted to degree of polymerization (DP) or to intrinsic fluidity, if desired.
Solutions of cellulose are not Newtonian liquids; that is, their viscosity depends upon the rate-of-shear or velocity gradient during measurement. This effect is smaller for samples of low molecular mass (DP) and at low concentrations than for high-DP samples and at high concentrations. For the celluloses and concentrations included within the limits set forth in this test method, the effect of rate-of-shear is assumed to be negligible for referee purposes. For other conditions and for research purposes this assumption may be invalid, but to discuss ways of accounting for this effect is beyond the scope of the present test method.
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 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D1795 − 96 (Reapproved2007)
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 (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Specification E1 was replaced with Specification E2251 in Section 2 and 5.2 in June 2007.
1. Scope solution, and also that of the solvent, is determined at 25°C by
means of a calibrated glass capillary-type viscometer. The
1.1 This test method covers the determination of the intrin-
relative viscosity is calculated and the corresponding intrinsic
sic viscosity of purified celluloses such as bleached wood
viscosity is read from a table.
pulps, cotton linters, and regenerated cellulose. It is applicable
to all cellulose samples with an intrinsic viscosity of 15 dl/g or
4. Significance and Use
less. Most native (unpurified) celluloses have intrinsic viscos-
4.1 This test is a sensitive measure of the degradation of
ity values too high for measurement by this test method.
celluloseresultingfromtheactionofheat,light,acids,alkalies,
NOTE 1—The use of cuprammonium hydroxide solution for regular
oxidizing and reducing agents, and the like, used in its
viscosity determination is described in Method T206 m-55 of the
processingorpurification.Theintrinsicviscosityvaluemaybe
Technical Association of Pulp and Paper Industry on “Cuprammonium
Disperse Viscosity of Pulp,” and Joint Army-Navy Specifications JAN- converted to degree of polymerization (DP) or to intrinsic
C-206.
fluidity, if desired.
1.2 The values stated in SI units are to be regarded as the
4.2 SolutionsofcellulosearenotNewtonianliquids;thatis,
standard. The values given in parentheses are for information
their viscosity depends upon the rate-of-shear or velocity
only.
gradientduringmeasurement.Thiseffectissmallerforsamples
1.3 This standard does not purport to address all of the oflowmolecularmass(DP)andatlowconcentrationsthanfor
safety concerns, if any, associated with its use. It is the high-DPsamplesandathighconcentrations.Forthecelluloses
responsibility of the user of this standard to establish appro- and concentrations included within the limits set forth in this
priate safety and health practices and determine the applica- test method, the effect of rate-of-shear is assumed to be
bility of regulatory limitations prior to use. negligible for referee purposes. For other conditions and for
research purposes this assumption may be invalid, but to
2. Referenced Documents
discuss ways of accounting for this effect is beyond the scope
2.1 ASTM Standards:
of the present test method.
D445Test Method for Kinematic Viscosity of Transparent
and Opaque Liquids (and Calculation of DynamicViscos-
5. Apparatus
ity)
5.1 Viscometer, Glass, Capillary Type—The Cannon-
D629Test Methods for Quantitative Analysis of Textiles
Fenske, Ubbelohde, or similar capillary type instrument as
E2251Specification for Liquid-in-Glass ASTM Thermom-
described in Test Method D445 is recommended. In order to
eters with Low-Hazard Precision Liquids
avoidcorrectionforthekineticenergyeffect,chooseaviscom-
eterwithasmallenoughcapillarytogiveanoutflowtimeof80
3. Summary of Test Method
s or more for the Cannon-Fenske type. (Asize 100 viscometer
3.1 Aweighedsampleofthematerialisdissolvedina0.5M
is normally used for the sample solution and a size 50 for the
cupriethylenediamine hydroxide solution.The viscosity of this
solvent.)
5.2 Thermometer—ASTM Kinematic Viscosity Thermom-
This test method is under the jurisdiction of ASTM Committee D01 on Paint
eter for use at 25°C, having a range from 19 to 27°C and
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
conforming to the requirement for Thermometer 17C as
CurrenteditionapprovedJune1,2007.PublishedJuly2007.Originallyapproved
prescribed in Specification E2251.
ε1
in 1960. Last previous edition approved in 2001 as D1795–96(2001) . DOI:
10.1520/D1795-96R07E01.
5.3 Bath—Aconstant-temperature bath at 25°C suitable for
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
immersion of the viscometer so that the reservoir or the top of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the capillary, whichever is uppermost, is immersed at least 50
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. mm, and with provision for visibility of the instrument and the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D1795 − 96 (2007)
thermometer. Firm supports for the viscometer shall be pro- 8. Calibration of Viscometer
vided; or the viscometer may be sealed in as an integral part of
8.1 The following directions apply to the Cannon-Fenske
the bath. Either a liquid bath with thermostatic regulation and
viscometer(Note3).Theyshouldbemodifiedaccordingtothe
astirreroravaporbathwithpressureregulationispermissible.
operating instructions for other types of viscometers. The
The efficiency of the stirring and the balance between heat
viscometers shall be calibrated (Note 4) by means of liquids
losses and heat input must be such that the temperature of the
having known viscosities approximately equal to those of the
bath medium does not vary by more than 60.1°C over the
solvent and cellulose solutions respectively (1.2 and 12 cP,
length of the viscometer, or from viscometer to viscometer in
approximately).
the various bath positions. If a vapor bath is used, there must
NOTE 3—Detailed specifications and directions for filling, calibrating,
be no temperature gradient over the length of the viscometer
and measurement with types of capillary viscometers most used are given
greater than that permitted in a liquid bath.
in Test Method D445.
5.4 Timer—A stop watch or other spring-activated timing NOTE4—Calibrationoftheviscometersmaybeavoidedifbothsolvent
and solution are measured in the same instrument. Then the relative
device or electrical timing device shall be used, graduated in
viscosity is nearly the ratio of outflow times for solution and solvent,
divisions of 0.2 s or less, and accurate to within 0.05% when
respectively. This simplification involves two assumptions. The first, that
tested over not less than a 10-min period. Such electrical
the densities of solution and solvent are equal, holds very well for the
timing devices shall be used only on electrical circuits of
dilute solutions used in these tests. The second, that the kinetic energy
continuously controlled frequency. Frequency-controlled de- correction is zero, depends upon the choice of viscometer. If the one used
gives convenient outflow times for the solution of less than 150 s, then it
vices of suitable capacity for laboratory purposes, accurate to
will be too fast for the solvent. The kinetic energy correction is zero,
within 1 part in 10 000 should be used. Errors exceeding
depending upon flow. On the other hand, if one is chosen so that the
0.05% of a 10-min interval may occur in timing devices
outflow time for the solvent is large enough (80 s or more), then the times
actuated by electrical synchronous motors driven by most
for the solutions will in most cases be inconveniently long. For some
public power systems, which are intermittently and not con- work, however, it may be desirable to make some sacrifice in accuracy or
in convenience during measurement in order to avoid calibration and
tinuously controlled.
using two sizes of viscometers.
6. Reagent 8.2 Bymeansofapipet,add7.0mLofthecalibratingliquid
totheviscometer,inaconstant-temperaturebathat25 60.1°C
6.1 Cupriethylenediamine Hydroxide Solution (1.00 6 0.01
(or fill as described in Test Method D445, Appendix A).
M), in copper, with the molar ratio of ethylenediamine to
copper of 2 6 0.1 to 1. This solvent may be prepared in the 8.3 When the liquid has reached temperature equilibrium
laboratory. It is also commercially available.
with the bath (in about 5 min), determine the outflow time t by
drawingthetopmeniscusoftheliquidabovethemarkbetween
7. Reference Materials
thetwobulbsandmeasuringthetimerequiredforthemeniscus
to pass from this mark to the mark below the lower bulb. Take
7.1 Viscosity Oil Standards—Calibrating oils in the speci-
the average of two or more observations, which should differ
fiedrangesofviscosity. Aqueoussolutionsofglycerolmaybe
by not more than 0.2 s.
used instead of standardized oils; the compositions for various
viscosities are given in chemical handbooks. The applicable
8.4 Determine the viscometer constant C by the equation:
viscosity oil standards (Note 2) are listed in Table 1.
C 5 η/dt (1)
where:
η = viscosity of the calibrating liquid, cP,
TABLE 1 Viscosity Oil Standards
d = density, g/mL, and
Viscometer Viscosity Oil Standard
t = time, s.
Approximate
Absolute Viscosity
Size Designation Absolute Viscosity
A
Range, cP
at 25°C (77°F), cP
9. Preparation of Sample
50 0.9to3.5 S-3 3.3
100 3.3 to 13.3 S-6 7.7 9.1 To avoid undesirable effects from long heating at high
A
temperature, samples should be air-dried and the moisture
For solution with density of 0.9.
content determined on a portion that is not used for measure-
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.
NOTE2—Theviscosityoilstandardsareavailableonlyas4.7-m (1-pt)
samples. More than 1 pt of any given oil (for example, duplicate samples)
9.2 Soft, sheeted pulp should be picked apart with tweezers
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
funnel, and dried at a temperature below 100°C (preferably
Thesolesourceofsupplyoftheviscosityoilstandardsknowntothecommittee
roomtemperature).Loosepulpshouldbepickedapartbyhand
atthistimeisCannonInstrumentCo.,P.O.Box16,StateCollege,PA16801.Ifyou
to break up any lumps. Slurried or slush pulps should be
are aware of alternative suppliers, please provide this information to ASTM
formed into thin sheets and dried. Yarn and staple should be
International Headquarters. Your comments will receive careful consideration at a
meeting of the responsible technical committee, which you may attend. washed in warm water containing a little detergent to remove
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D1795 − 96 (2007)
the finish, rinsed thoroughly, dried (at low temperature), and screwcap.Add25.0mLofdistilledwaterfromapipetorburet,
fluffed.(Itwillbefoundhelpfultocutyarnandlongstapleinto insert the stopper or cap, and shake in order to wet out and
short lengths, say 13 mm ( ⁄2 in.), before washing.) Fabrics disperse the sample. Sweep the air from the vessel with a
should be cut into small pieces, desized (see Test Methods streamofnitrogenand,withthenitrogenstillflowing,add25.0
D629), thoroughly washed, and dried. Raveling will be helpful mLof solvent. Stopper or cap tightly and shake vigorously by
before dissolving samples that tend to get in the solvent. handorinamechanicalshakeruntilthecelluloseiscompletely
Materials containing a considerable amount of non-cellulosic dissolved.
matter must first be purified; such treatments lie outside the
NOTE 5—Most work pulp and regenerated celluloses dissolve within 5
scope of this test method.
min. Mercerized celluloses do not dissolve as easily in cupriethylenedi-
amine as in cuprammonium solvent and require longer times (up to 1 h).
10. Preparation of Solution
Some operators report difficulty in dissolving native celluloses including
cotton linters with degree of polymerization (DP) as low as that of wood
10.1 The sample size is dependent upon the nature of the
pulps.Thedifficultyshowsupbymuchpoorerprecisionofresultsthanthe
material,smallermassesofhigh-viscositycellulosesandlarger
1 to 2% that is normally obtained between measurements made with two
masses of low-viscosity celluloses being used in order to keep
ormoresolutionsofthesamesample.Evensolutionsthatleavenoresidue
on fritted-glass filters have been observed to give erratic results. Inad-
the viscosity of the solutions within rather narrow limits.
equate dispersion of the sample is apparently the cause, and two
(Working at nearly constant viscosity reduces the effect of rate
modifications in procedure have been recommended in such cases. One is
of shear upon the measurements.) The concentration for each
to add about 0.04% wetting agent to the water used to wet out the
sample is chosen according to the rule:
sample. The other requires use of cupriethylenediamine solutions of two
concentrations:Thesampleiswettedoutwithonesolutionthatis0.167M
@η#c 5 3.0960.5 (2)
in copper and dispersion is completed by adding the second solution,
1.000 M in copper, in such volume as to make the final copper
where:
concentration 0.500 M.
[η] = intrinsic viscosity, dL/g, and
c = cellulose concentration, g/dL.
11. Measurement of Viscosity
Obviously, use of this rule requires knowledge of the
11.1 Transfer 7.0 mL of the solution by means of a syringe
approximate intrinsic viscosity of the sample before the con-
or pipet to a viscometer previously placed in the bath at 25°C
centration can be estimated. In routine control work, such
and flushed with nitrogen (or fill as described in Test Method
information is available. If it is not, Table 2 will serve as an
D445, Appendix A). Allow at least 5 min for the solution to
approximate guide.
reach bath temperature.
10.2 Make up a preliminary solution of about the indicated
11.2 By applying either pressure (with nitrogen) or suction,
concentration, and determine the viscosity as described in
drawthesolutionintothelowerbulboftheviscometeruntilthe
Sections 11 and 12. From the relative viscosity thus obtained,
top meniscus is a little above the mark between the two bulbs.
find the approximate value of the intrinsic viscosity by means
Measure the time t required for the meniscus to pass from this
of Table 3. From this determine the concentration needed to
mark to the mark below the lower bulb. Repeat at least twice
give: [η]c=3.0. If this preliminary solution does not give a
and average the observations, which should not differ by more
value of [η]c of 3.0 6 0.5, prepare a second solution of the
than 0.3%.
indicated concentration for the final viscosity measurement.
11.3 In the same way, measure the outflow time t for the
10.3 Alkaline solutions of cellulo
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