ASTM D1348-94(2003)
(Test Method)Standard Test Methods for Moisture in Cellulose
Standard Test Methods for Moisture in Cellulose
SIGNIFICANCE AND USE
These test methods determine the amount of moisture contained in a cellulose sample which determines the amount of bone dry cellulose present in a sample. The actual amount of cellulose in a sample is an essential entity when using cellulose as a starting material for the production of cellulose derivatives.
SCOPE
1.1 These test methods cover the determination of moisture in cellulose using two oven-drying procedures and one Karl Fischer procedure.
1.2 The test procedures appear in the following order:SectionsTest Method A-Specimen Weighed in OvenTest Method B-Specimen Weighed Outside of OvenTest Method C-Karl Fischer Method
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
Designation:D1348 –94(Reapproved2003)
Standard Test Methods for
Moisture in Cellulose
This standard is issued under the fixed designation D 1348; 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.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope various parts of the lot and having the proper proportion of
edge and center material.
1.1 These test methods cover the determination of moisture
3.1.2 Except for those samples taken in an atmosphere with
in cellulose using two oven-drying procedures and one Karl
which the sample is in equilibrium, the moisture content of the
Fischer procedure.
sample will begin to change immediately after it is removed
1.2 The test procedures appear in the following order:
from its original surroundings. This change can be reduced by
Sections
taking extra layers of sheeted material and discarding a few
Test Method A—Specimen Weighed in Oven 4-10
Test Method B—Specimen Weighed Outside of Oven 11-17
layers from the top and bottom before weighing, folding, or
Test Method C—Karl Fischer Method 18-25
rolling the sample to reduce the exposed area, and by placing
1.3 The values stated in SI units are to be regarded as the small samples in cans or bottles and protecting larger samples
standard. The values given in parentheses are for information
by wrapping in rubber sheets, moistureproof cellophane, or
only. other protective wrappings. These means do not provide
1.4 This standard does not purport to address all of the
continuous protection, and the test samples should be weighed
safety concerns, if any, associated with its use. It is the as soon as possible.
responsibility of the user of this standard to establish appro-
3.1.3 When possible, bulk samples should be taken. These
priate safety and health practices and determine the applica- samples should weigh from 100 to 300 g (3.5 to 10.5 oz), the
bility of regulatory limitations prior to use.
larger samples being taken when the moisture content is low or
variable. Following the initial weighing, the bulk samples
2. Significance and Use
should be cut up or torn into small pieces and then mixed and
2.1 These test methods determine the amount of moisture
allowed to stand overnight or longer in a sealed container to
contained in a cellulose sample which determines the amount
obtain moisture equilibrium before weighing out test speci-
of bone dry cellulose present in a sample.The actual amount of
mens; or the sample may be allowed to come to approximate
cellulose in a sample is an essential entity when using cellulose
equilibrium with the laboratory air and reweighed to determine
as a starting material for the production of cellulose deriva-
moisture change before weighing test specimens. The latter
tives.
procedure is recommended since it permits routine weighing of
samples without the use of special weighing bottles or boxes,
3. Sampling
and a series of accumulated samples can be weighed simulta-
3.1 Cellulose in a variety of forms is sampled for moisture,
neously. Predrying is very desirable on samples with a high
and no single set of directions can be given that is applicable
moisture content (more than 5 % above equilibrium value).
to all types of cellulose material. The following general
When samples have been predried, calculate the moisture lost,
considerations should be borne in mind.
as follows:
3.1.1 Cellulose, either in compact form, such as wood,
R 5 [M – A/A] 3 100 (1)
sheeted pulp or paper, baled cotton or baled staple rayon, or in
loose form such as sawdust or chips, may have an appreciably
where:
R = moisture, air-dry sample basis, %,
different moisture content in sections lying relatively close
M = original mass of the sample, g, and
together. In order to secure representative samples, therefore, a
A = air-dry mass of sample, g.
bulk sample should be made up of small portions taken from
3.1.4 The apparent moisture subsequently observed when
testing a predried sample must be calculated on the basis of the
These test methods are under the jurisdiction of ASTM Committee D01 on
original sample mass in order to get the original moisture
Paint and Related Coatings, Materials, and Applications and are the direct
content. Calculate the original mass of the air-dried sample as
responsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
follows:
Current edition approved Oct. 1, 2003. Published October 2003. Originally
approved in 1954. Last previous edition approved in 1994 as D 1348 – 94 (1998).
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
D1348 –94 (2003)
be weighed in an oven, use containers such as open wire grills or baskets.
Original sample mass, g 5 [A 3 ~100 1 R!#/100 (2)
For small specimens to be weighed out of the oven, use wire screen
NOTE 1—Example—If1000g(35oz)ofbulk(wet)sampleonexposure
baskets that will fit in weighing bottles, but if the specimen is powdery or
to air lose 200 g (7 oz) of water, the apparent moisture content is 20 % and
tends to shed lint or fine short fibers, use a small weighing bottle or metal
equivalent regain is 25 %. If an 8-g (0.28-oz) specimen of the air-dry
boxes.
material is taken for drying in the oven, the original mass is 8 3 1.25 = 10
7.2 Dry the specimen for 2 h at 105 6 3°C, passing a
g (0.35 oz).
current of dry air into the bottom of the oven during the drying
TEST METHOD A—SPECIMEN WEIGHED IN OVEN
period. (If dry air is not forced through the oven, dry for 4 h.)
4. Scope NOTE 4—Reproducible but less accurate values (under unfavorable
conditionstheabsoluteerrormaybeashighas1 %)willbeobtainedifthe
4.1 This test method for moisture determination is appli-
current of predried air is omitted. Since the error will be identical for all
cable to a variety of cellulose types and can be used in most
similar samples in the oven at one time, the results obtained in these cases
cases where a sample does not contain nonaqueous material
will be comparable. The magnitude of error will vary directly with the
volatile at 105°C. The test method can be used for samples
relative humidity of the air entering the oven and with the equilibrium
moisture content of samples at low relative humidity. Thus, the error will
having either high or low moisture content.
be higher on regenerated cellulose than on wood pulp or cotton, but it still
would not usually be greater than 0.2 %, absolute.
5. Summary of Test Method
7.3 At the end of the specified period, cut off the flow of air
5.1 The specimen is heated to constant mass at 105°C in a
and weigh the specimen without removing it from the oven.
ventilated gravity-convection oven, in a current of dry air, for
Continue drying for ⁄2 h longer, with the normal air flow, and
a period of 2 h. If no dry air is used, the specimen is heated for
reweigh the specimen. Repeat the drying and weighing until
4h.
the mass loss between successive weighings is not more than
6. Apparatus
0.005 g, or until the specimen shows a gain in mass. Designate
this mass as D.
6.1 Oven with Built-In Weighing Equipment—Such an oven
employs a system of tared containers mounted on a table or 7.4 Additional specimens should not be placed in the oven
until the first specimens have attained constant mass.
track that can be rotated to bring specimens to a specific point
intheoven,wherethespecimenandcontainercanbeplacedon
8. Calculation
a hook or a tray connected to an outside balance. The oven
8.1 Calculate moisture, as measured in the oven, as follows:
must be capable of maintaining a constant temperature of 105
6 3°C, with an average temperature of 105°C; continuous
operation below 105°C is not satisfactory.
Moisture content, % 5 [~M – D/M] 3 100 (3)
NOTE 2—In ovens having heating elements at the bottom only, and no
Moisture, dry basis ~regain!,% 5 [~M – D!/D] 3 100 (4)
cross circulation, the temperature of the lower shelves should be checked
before they are used.
where:
6.2 Dry Air Stream—Air, dried by passing through silica
M = original mass of specimen, and .
gel, aluminum oxide, concentrated sulfuric acid, or other
D = mass of oven-dry specimen.
suitable drying agent, should be passed through the oven at a
9. Report
rate sufficient to effect a complete change once every 2 min. If
the air is dried by means of concentrated sulfuric acid,
9.1 Report the moisture in the cellulose on either or both of
adequate traps must be provided. The use of sulfuric acid
the following bases:
followed by perchloric drying agents should be avoided. 9.1.1 On the basis of the original sample, when it is termed
6.3 Shallow Glass Weighing Bottles—Bottles with ground
“moisture content,” “moisture as received,” or “moisture as is”
glass stoppers, measuring 30 mm high, and having a capacity basis.
of 30 mL.
9.1.2 On the basis of the oven-dry cellulose, when it is
6.4 Seamless Metal Weighing Boxes, having a wall height,
termed “moisture, dry basis” or “moisture regain.”
when open, preferably not over 25.4 mm (1 in.).
9.2 In order to avoid confusion always use the appropriate
term.
7. Procedure
10. Precision and Bias
7.1 Remove the basket, shallow pan, or other container
10.1 Precision:
supplied for use with the oven (Note 3). Weigh the container
10.1.1 Statistical analysis of intralaboratory (repeatability)
and place in it a specimen of 10 to 50 g (0.35 to 1.75 oz)
test results on samples containing 5 to 15 % moisture indicates
weighedtothenearest0.005g.DesignatethismassasM.Place
a precision of 60.14 % at the 95 % confidence level.
the specimen in a tared container in the oven in such a manner
10.1.2 Statistical analysis of interlaboratory (reproducibil-
that it can be reweighed without removal from the oven.
ity) test results on samples containing 5 to 15 % moisture
NOTE 3—Experience has shown that when yarn and fiber specimens are
indicates a precision of 60.2 % at the 95 % confidence level.
left in comparatively deep weighing bottles in the oven, relatively
10.2 Bias—No justifiable statement can be made on the bias
discordantresultsareobtainedandthedryingperiodisunnecessarilylong.
of the procedure for measuring moisture in cellulose because
To avoid these difficulties specimens should be dried in containers that
give the cellulose free access to the air. For fibrous or bulky materials to no suitable reference material exists.
D1348 –94 (2003)
TEST METHOD B—SPECIMEN WEIGHED OUTSIDE successive weighings is not more than 0.005 g (or until the
OF OVEN specimen shows a gain in mass). Designate the lowest ob-
served mass as D.
11. Scope 14.5 When constant mass has been obtained, discard the
specimen and weigh the weighing bottle (plus basket) or can.
11.1 The scope and application of this test method are the
Designate this mass as T.
same as those of Test Method A (see Section 4).
14.6 Do not place additional specimens in the oven until the
first specimens have attained constant mass.
12. Summary of Test Method
12.1 See Test Method A (Section 5).
15. Calculation
15.1 Calculatemoisture,asmeasuredoutsideoftheoven,as
13. Apparatus
follows:
13.1 Oven Without Built-In Weighing Equipment—Any
Moisture content, % [~M – D!/~M – T!# 3 100 (5)
ventilated oven capable of maintaining a constant temperature
of 105 6 3°C, with an average temperature of 105°C;
Moisture, dry basis, ~regain!,% 5 [~M – D!/~D – T!# 3 100 (6)
continuous operation below 105°C is not satisfactory.
where:
NOTE 5—In ovens having heating elements at the bottom only, and no
M = original mass of the specimen (plus basket) and
cross circulation, the temperature of the lower shelves should be checked
weighing bottle,
before they are used.
D = oven-dry mass of the specimen (plus basket), and
13.2 Dry Air Stream—See 6.2.
T = mass of the empty weighing bottle (plus basket).
13.3 Shallow Glass Weighing Bottles—See 6.3.
13.4 Seamless Metal Weighing Boxes—See 6.4.
16. Report
13.5 Weighing Bottles, glass with ground-glass stoppers,
16.1 Report the moisture in the cellulose as directed in
approximately 40 mm wide and 80 mm high.
Section 9.
13.6 Wire Baskets—Fitted baskets for weighing bottles
made from approximately 15-mesh stainless steel, Monel, or
17. Precision and Bias
othersuitablescreen.Theheightanddepthofthebasketwillbe
17.1 See Section 10.
determined by the weighing bottle used; the basket must slide
into and out of the bottle without binding. The basket should
TEST METHOD C—KARL FISCHER METHOD
have a solid bottom, but no top is required.
18. Scope
14. Procedure
18.1 This test method covers the determination of moisture
in cellulose by titration with Karl Fischer reagent. The test
14.1 If the sample is free of lint, dust, or short fibers, place
method is applicable to all types and forms of cellulose. It is
approximately 10 g (0.35 oz) of the sample into a previously
especially useful with samples containing nonaqueous material
dried and desiccated wire basket (Note 2) contained in a dry
volatile at 110°C, since such substances interfere in the
weighing bottle. Stopper the weighing bottle, and weigh to the
oven-drying methods.Anhydrides, alkalies, and large amounts
nearest 0.001 g. Designate this mass as M. Remove the basket
of aldehydes and ketones interfere.
containingthespecimenfromtheweighingbottleandplacethe
18.2 The Karl Fischer titration method is especially valu-
basket, weighing bottle, and stopper in the oven. If the
able where only small amounts of samples are available. The
specimen includes powder-like material, transfer the specimen
procedure lends itself to multiple determinations.
directly into a small weighing bottle or can. Stopper the bottle
18.3 It is essential that the Karl Fischer reagent, standard
andweightothenearest0.001g(M).Removethestopperfrom
water solution, and anhydrous methanol be protected from
the bottle and place the bottle containing the specimen and the
atmospheric moisture at all times. During the titration a stream
stopper in the oven.
of dry air or nitrogen will protect the contents of the titration
14.2 Dry for2hat105 6 3°C, passing a current of dry air
flask from atmospheric moisture pick-up.
into the bottom of the oven during the drying period. (If dry air
is not forced through the oven, dry for 4 h.)
19. Summary of Test Method
14.3 At the end of the specified period, quickly place the
19.1 An excess of Karl Fischer reagent is added to the
basket and specimen in the weighing bottle again and stopper
specimen suspended in anhydrous methanol. After shaking for
it (or stopper directly). Remove the weig
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