ASTM D6942-03
(Test Method)Standard Test Method for Stability of Cellulose Fibers in Alkaline Environments
Standard Test Method for Stability of Cellulose Fibers in Alkaline Environments
SIGNIFICANCE AND USE
This method is intended to provide a generalized procedure for determining the stability of cellulosic pulp fibers exposed to alkaline environments. Specifically, this method allows various pulp types to be compared with respect to the effect of exposure to alkaline conditions on the strength of individual cellulosic fibers based on a zero-span tensile test. The time intervals listed in the procedure are not critical, and more intervals of shorter or longer duration may be added. In addition, the procedure may be simplified by removing some of the intermediate intervals so long as a range of intervals is determined. An example of a simplified procedure would be to determine 4 intervals (for example, 1 day, 1 week, 2 weeks, 4 weeks; or 1 day, 3 day, 7 day, 14 day).
The specified solution (1N NaOH) is strongly alkaline. Although this alkali concentration is higher than some environments that would be simulated by this test, the stronger pH provides better differentiation between different cellulose fiber types. Although alkaline stability based on other alkalis (for example, KOH, Ca(OH)2, etc.) at a different concentration could be determined by this method, 1N NaOH is to be considered the standard solution. Alkaline stability results from other treatments may be reported in addition to the standard solution if the additional solution(s) provide useful information.
SCOPE
1.1 This test method describes a procedure for determining the effect of exposure to alkaline environments on the strength of cellulose fibers. An alkaline environment is defined to be any matrix in which the pH is greater than 8 for a period of 2 or more h.
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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Designation:D6942–03
Standard Test Method for
Stability of Cellulose Fibers in Alkaline Environments
This standard is issued under the fixed designation D 6942; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope formed into standard handsheets (see TAPPI T 205) for
strength testing. Zero-span tensile testing (see TAPPI T 231) is
1.1 This test method describes a procedure for determining
used to determine the effect on fiber strength.
the effect of exposure to alkaline environments on the strength
4.3 A stability ratio is defined based on the ratio of the
of cellulose fibers. An alkaline environment is defined to be
zero-span tensile of alkali treated fibers divided by the zero-
any matrix in which the pH is greater than 8 for a period of 2
span tensile of untreated (control) fibers.
or more h.
1.2 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 This method is intended to provide a generalized pro-
responsibility of the user of this standard to establish appro-
cedure for determining the stability of cellulosic pulp fibers
priate safety and health practices and determine the applica-
exposed to alkaline environments. Specifically, this method
bility of regulatory limitations prior to use.
allows various pulp types to be compared with respect to the
2. Referenced Documents effect of exposure to alkaline conditions on the strength of
individual cellulosic fibers based on a zero-span tensile test.
2.1 ASTM Standards:
The time intervals listed in the procedure are not critical, and
D 1348 Test Methods for Moisture in Pulp
more intervals of shorter or longer duration may be added. In
D 1695 Terminology of Cellulose and Cellulose Deriva-
addition,theproceduremaybesimplifiedbyremovingsomeof
tives
the intermediate intervals so long as a range of intervals is
2.2 TAPPI (Technical Association of the Pulp & Paper
determined.An example of a simplified procedure would be to
Industry) Standards:
determine 4 intervals (for example, 1 day, 1 week, 2 weeks, 4
T 205 Forming Handsheets for Physical Tests of Pulp
weeks; or 1 day, 3 day, 7 day, 14 day).
T 231 Zero-span Breaking Strength of Pulp (Dry Zero-span
3 5.2 The specified solution (1N NaOH) is strongly alkaline.
Tensile)
Although this alkali concentration is higher than some envi-
3. Terminology ronments that would be simulated by this test, the stronger pH
provides better differentiation between different cellulose fiber
3.1 Definitions—For standard terminology of cellulose and
types. Although alkaline stability based on other alkalis (for
cellulose derivatives, see Terminology D 1695.
example, KOH, Ca(OH) , etc.) at a different concentration
4. Summary of Test Method
could be determined by this method, 1N NaOH is to be
consideredthestandardsolution.Alkalinestabilityresultsfrom
4.1 This test method can be used to compare different
other treatments may be reported in addition to the standard
cellulose pulp fiber types based on their response to a standard
solution if the additional solution(s) provide useful informa-
alkaline solution. The stability factor defined below can be
tion.
usedtomeasuretheeffectofexposuretoalkalineconditionson
fiber strength.
6. Interferences
4.2 Cellulose fibers are treated with a standard alkaline
6.1 There are no known interferences for this method.
solution for a specified interval, washed free of alkali, and then
7. Apparatus
This test method is under the jurisdiction of ASTM Committee D01 on Paint 7.1 Handsheeting Apparatus, as defined in TAPPI T 205.
and Related Coatings, Materials, andApplications and is the direct responsibility of
7.2 Zero-span Tensile Tester, as described in TAPPI T 231.
Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
7.3 Moisture Balance.
Current edition approved July 10, 2003. Published August 2003.
7.4 Analytical Balance.
Annual Book of ASTM Standards, Vol 06.03.
Available from TechnicalAssociation of the Pulp and Paper Industry (TAPPI),
P.O. Box 105113,Atlanta, GA30348; 15Technology Parkway South, Norcross, GA
30092.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6942–03
8. Reagents and Materials screen (100 mesh), washing with tap water until washings are
substantially neutral (pH=7to 7.5), and then air drying.
8.1 1N sodium hydroxide (NaOH).
13.4 Prepare 2 sets of standard handsheets according to
TAPPIT205 for each time interval. One set will be made from
9. Hazards
pulp that has not been treated with sodium hydroxide and will
9.1 Sodium hydroxide solutions are corrosive, and thus
be the control set. The other set will be prepared from fibers
harmful to the skin and eyes. Wear safety glasses or goggles,
that have been exposed to alkali for the designated time
gloves, and lab coat or chemical apron. while working with
interval. These 2 sets of handsheets will be prepared on the
caustic solutions.
same day.
13.5 Each set of handsheets will be tested for zero-span
10. Sampling, Test Specimens, and Test Units
tensile according to TAPPI T 231.
10.1 Va
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