Standard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials

SIGNIFICANCE AND USE
This test method distinguishes between hot melts having different apparent viscosities. It is believed that apparent viscosity determined by this procedure is related to flow performance in application machinery operating under conditions of low shear rate. Apparent viscosity as determined by this test method may not correlate well with end-use applications where high shear rates are encountered.
Materials of the type described in this procedure may be quite non-Newtonian and as such, the apparent viscosity will be a function of shear rate under the conditions of test. Although the viscometer described in this test method generally operates under conditions of relatively low shear rate, differences in shear effect can exist depending upon the spindle and rotational speed conditions selected for the test program. Maximum correlation between laboratories, therefore, depends upon testing under conditions of equivalent shear.
Approximate shear rates using various spindles are shown in Table .
SCOPE
1.1 This test method covers the determination of the apparent viscosity of hot melt adhesives and coating materials compounded with additives and having apparent viscosities up to 200 000 millipascal second (mPa·s) (Note 3) at temperatures up to 175°C (347°F).
Note 1—Although precision has not been studied, this procedure may be adaptable to viscosities higher than the present 200 000-mPa·s limit and temperatures above 175°C (347°F). Equipment described in this test method permits testing of materials having viscosities as high as 16 × 106 mPa·s and provides temperatures up to 260°C (500°F).  
Note 2—For petroleum waxes and their blends having apparent viscosities below 15 mPa·s, Test Method D445 is especially applicable.  
Note 3—One pascal second (Pa·s) = 1000 centipoise (CP); one millipascal second = one centipoise.  
1.2 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.3 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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Publication Date
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ASTM D3236-88(2009) - Standard Test Method for Apparent Viscosity of Hot Melt Adhesives and Coating Materials
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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: D3236 − 88(Reapproved 2009)
Standard Test Method for
Apparent Viscosity of Hot Melt Adhesives and Coating
Materials
This standard is issued under the fixed designation D3236; 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 3.1.1 apparent viscosity—the viscosity determined by this
test method and expressed in millipascal seconds. Its value
1.1 This test method covers the determination of the appar-
may vary with the spindle and rotational speed selected
ent viscosity of hot melt adhesives and coating materials
because many hot melts are non-Newtonian.
compounded with additives and having apparent viscosities up
3.1.2 viscosity—the ratio of shear stress to shear rate. The
to200000millipascalsecond(mPa·s)(Note3)attemperatures
viscosity of a liquid is a measure of the internal friction of the
up to 175°C (347°F).
liquid in motion. The unit of dynamic viscosity is the pascal
NOTE 1—Although precision has not been studied, this procedure may
second. For a Newtonian liquid, the viscosity is constant at all
beadaptabletoviscositieshigherthanthepresent200000-mPa·slimitand
shear rates. For a non-Newtonian liquid, viscosity will vary
temperatures above 175°C (347°F). Equipment described in this test
method permits testing of materials having viscosities as high as 16×10 depending on shear rate.
mPa·s and provides temperatures up to 260°C (500°F).
NOTE 2—For petroleum waxes and their blends having apparent
4. Summary of Test Method
viscosities below 15 mPa·s, Test Method D445 is especially applicable.
4.1 A representative sample of the molten material to be
NOTE 3—One pascal second (Pa·s)=1000 centipoise (CP); one milli-
pascal second=one centipoise. tested is maintained in a thermally controlled sample chamber.
Apparent viscosity is determined under temperature equilib-
1.2 The values stated in SI units are to be regarded as the
riumconditionsusingaprecisionrotatingspindletypeviscom-
standard. The values in parentheses are for information only.
eter. Data obtained at several temperatures can be plotted on
1.3 This standard does not purport to address all of the
appropriate semi-logarithmic graph paper and apparent viscos-
safety concerns, if any, associated with its use. It is the
ity at intermediate temperatures can be estimated.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5. Significance and Use
bility of regulatory limitations prior to use.
5.1 Thistestmethoddistinguishesbetweenhotmeltshaving
different apparent viscosities. It is believed that apparent
2. Referenced Documents
2 viscosity determined by this procedure is related to flow
2.1 ASTM Standards:
performance in application machinery operating under condi-
D445Test Method for Kinematic Viscosity of Transparent
tions of low shear rate. Apparent viscosity as determined by
and Opaque Liquids (and Calculation of DynamicViscos-
this test method may not correlate well with end-use applica-
ity)
tions where high shear rates are encountered.
3. Terminology
5.2 Materialsofthetypedescribedinthisproceduremaybe
3.1 Definitions: quite non-Newtonian and as such, the apparent viscosity will
be a function of shear rate under the conditions of test.
1 Although the viscometer described in this test method gener-
This test method is under the jurisdiction of ASTM Committee D02 on
ally operates under conditions of relatively low shear rate,
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee
D02.10.0A on Physical/Chemical Properties.
differencesinsheareffectcanexistdependinguponthespindle
Current edition approved Oct. 1, 2009. Published November 2009. Originally
and rotational speed conditions selected for the test program.
approved in 1973. Last previous edition approved in 2004 as D3236–88(2004).
Maximumcorrelationbetweenlaboratories,therefore,depends
DOI: 10.1520/D3236-88R09.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or upon testing under conditions of equivalent shear.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.3 Approximate shear rates using various spindles are
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. shown in Table A1.1.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3236 − 88 (2009)
TABLE 1 Suitable ASTM Thermometers
6. Apparatus
3 Scale
6.1 Viscometer, rotating spindle type with leveling stand. Immersion, ASTM Thermometer
Temperature Range Error,
mm Number
max
6.2 Viscometer Spindles, stainless steel.
90°C to 170°C 51 0.2°C 35C-62
6.3 Sample Chamber, with precision proportional tempera-
194°F to 338°F 51 0.5°F 35F-62
3,4
145°C to 205°C 76 0.4°C 100C-68
ture controller that provides control accuracy of 61.0°C
(1.8°F) or better through the range from 100 to 200°C (212 to
392°F).
provide the desired test temperature. Rotate the thermometer
6.4 Graph Paper, semi-logarithmic.
during temperature reading to minimize the effect of thermal
7. Calibration gradients in the sample. Continue temperature readings and
controller adjustment until minimum deviation from test tem-
7.1 The viscometer is precalibrated using Newtonian fluids
perature is obtained. Minimum deviation may vary between
by the manufacturer. No zero adjustment is provided, since
laboratories, depending upon the controller, but should in no
experience has shown that the zero point will not vary due to
caseexceed 60.5°C(0.9°F).Repeatthisprocedureforanytest
changes in the spring. The viscometer and spindles are preci-
temperature desired within the scope of this test method.
sion equipment and should be kept from undue shock and
mishandling. Physical damage to the instrument will often
8. Procedure
reveal itself as erratic or no oscillation of the pointer when the
8.1 Selection of Spindle—From the estimated viscosity of
instrument, with or without the spindle in place, is operated in
the sample and Table A1.1 in the Annex, select a viscometer
air. When operating normally, the pointer will be stable and
and spindle combination that will produce readings in the
have free oscillation about the zero point in air.
desired range.
7.2 Theinstrumentmaybefurthercalibratedusingstandard
NOTE 5—Use only the spindle shown to be appropriate for the
reference fluids. Suitable fluids are available in nominal
5 viscometer to be used.
viscosities up to 15000 mPa·s at 149°C (300°F). The proce-
8.1.1 Wheremorethanonespindleisavailablefortherange
dure for instrument calibration using standard reference fluids
selected, choose the spindle that produces results nearest the
isthatencompassedbythistestmethod.Resultsobtainedusing
midpoint of the measurable viscosity range. Viscometer scale
standard reference fluids should not deviate from the nominal
readings must be within the 10 to 95 range.
viscosity by more than 2%.
NOTE6—Caremustbetakeninthestorageandhandlingofspindlesand
7.3 Thetemperaturecontrollerofthetyperecommendedfor
assemblies. Protect them from dust, corrosive deposits, and mechanical
this procedure is factory calibrated and has control capability
abuse.Avoidtouchingthecalibratedsectionofthespindlewiththehands.
of 60.5% of the control point (61.0°C at 175°C). To further
Clean the spindle and sample chamber thoroughly after each use. A
check the controller and further establish controller settings,
recommended cleaning procedure is included in Annex A2.
use the following procedure: Place a sufficient quantity of low
8.2 Preparation of Sample—Place the required amount of
viscosity (500 mPa·s or less) hot melt in the sample container
representative sample (see Table 2) measured to the nearest
to permit immersion of the appropriateASTM thermometer to
0.005 g (or 0.05 mL if handled in the molten state) in the
theproperdepth.Donotpermitthethermometerbulbtoreston
sample chamber. Melt the sample in an oven set at the desired
the bottom of the sample container. Suitable thermometers are
test temperature or in the thermo-container preheated to the
shown in Table 1.
desired test temperature.Avoid excessive or prolonged heating
NOTE 4—Particular care must be taken not to overflow the sample of the sample to minimize thermal and oxidative effects. Use a
chamber when using the 100°C, 76-mm immersion thermometer.
freshsampleforeachtemperatureforwhichadeterminationis
to be made.
7.3.1 Insert the thermometer through the insulating cover of
the sample container and hold it in place at the point required
8.3 System Alignment and Spindle Insertion—After the
for proper immersion depth. Adjust the thermal controller to
sample is completely melted, lower the properly aligned and
leveled viscometer until the tips of the alignment bracket just
The sole source of supply of the viscometers and accessories known to the
committeeatthistimeisBrookfieldEngineeringLaboratories,Inc.,Stoughton,MA
TABLE 2 Sample Size Requirement
02072. If you are aware of alternative suppliers, please provide this information to
Approximate Approximate Sample
ASTM International Headquarters. Your comments will receive careful consider-
Spindle
A
Volume, mL Weight, g
ation at a meeting of the responsible technical committee, which you may attend.
Thesolesourceofsupplyofthetemperaturecontrollerknowntothecommittee
SC 4-18 8.00 6.40
atthistimeisAthenaControls,Inc.,2UnionRoad,WestConshohocken,PA19428. SC 4-21 8.00 6.40
If you are aware of alternative suppliers, please provide this information toASTM SC 4-27 10.50 8.40
SC 4-28 11.50 9.20
International Headquarters. Your comments will receive careful consideration at a
SC 4-29 13.00 10.40
meeting of the responsible technical committee, which you may attend.
SC 4-31 10.00 8.00
The sole source of supply of the calibration fluids known to the committee at
SC 4-34 9.50 7.60
this time is Brookfield Engineering Laboratories, Inc., Stoughton, MA 02072 or
A
Cannon Instrument Co., P. O. Box 16, State College, PA16801. If you are aware of
Based on typical molten specific gravity of 0.800. If the specific gravity of the
alternative suppliers, please provide this information to ASTM International
material to be tested varies greatly from this value, sample size must be adjusted
Headquarters.Your comments will receive careful consideration at a meeting of the
to ensure proper liquid level on the spindle shaft.
responsible technical committee, which you may attend.
D3236 − 88 (2009)
touch the top of the thermo-container, making contact directly the spindle to rotate at the lowest spindle speed available to
behind the locating ring. Raise the viscometer, positioning the minimize temperature gradients in the sample as well as
tips of the alignment bracket 2 mm ( ⁄16 in.) above the top of
possible shear effects. When temperature equilibrium is indi-
the thermo-container. Using both hands, gently slide the
cated, turn off the viscometer, remove the insulating cap, raise
thermo-container base until the tips of the alignment bracket
the viscometer and spindle, and inspect the liquid level on the
just touch the locating ring. Do not forcibly displace the
spindle shaft. It should extend about 3 mm ( ⁄8 in.) up the
alignment bracket (see Fig. 1). Screw the link coupling nut
spindle shaft beyond the upper, tapered portion of the spindle.
onto the viscometer coupling nut (note left-hand thread).
If the liquid level varies significantly from this, add or remove
Connectthecouplinglinktothespindle(andthecouplingnut).
sample to provide this level. Replace the insulating cap, and
Lower the spindle into the sample chamber and connect the
allow the unit to reestablish temperature equilibrium with the
link coupling nut to the viscometer coupling nut, noting the
spindlerotatingatthelowestavailablespeed.Continuespindle
left-hand thread. Pick up the insulating cap and place it over
rotation for 15 min after apparent equilibrium. Increase the
the sample chamber (see Fig. 1).
spindle speed to that required to produce a scale reading
nearest the midpoint of the scale, but in no case outside the 10
8.4 Viscosity Determination—Ensurethatthematerialinthe
sample chamber is completely molten and that temperature to 95-unit range. Engage the pointer clutch and stop the
controllersettingsareproper.Turnontheviscometerandallow viscometermotorwhenthepointerisinview.Recordthescale
FIG. 1 Apparatus for Viscosity Determination
D3236 − 88 (2009)
reading. Restart the viscometer motor, and allow at least five 11.1.1 Repeatability—The difference between two test re-
additionalrevolutionsofthespindle.Engagethepointerclutch sults, obtained by the same operator with the same apparataus
andstoptheviscometermotorwiththepointerinview.Record
under constant operating conditions on identical test material
the second dial reading. Repeat the above operation until three
would, in the normal and correct operation of the test method,
consecutive scale readings are obtained that differ by no more
exceed the following values in one case in twenty:
than 0.5 unit.
8.8% ofthemeanofthetworesults. (1)
9. Calculation
11.1.2 Reproducibility—The difference between two single
9.1 Determine the average of the three consecutive scale
and independent results obtained by different operators work-
readings which differ by no more than 0.5 scale unit. To
ing in different laboratories in identical test material would, in
convert to millipascal seconds, multiply this value by the
the long run, exceed the following value only in one case in
appropriate factor taken from either the instrument instruction
twenty:
manual or Table A1.2. Repeat this for each temperature.
25.4% ofthemeanofthetworesults. (2)
NOTE 7—If it is necessary to interpolate for viscosity values at
NOTE 9—The precision of this test method is based on a round-robin
intermediate temperatures, plot a series of observed apparent viscosity
conducted using six wax-based hot melt materials that are believed to be
valuesonthelogarithmicscaleandthecorrespondingtesttemperatureson
representative of the class. Tests were conducted at three temperatures by
the linear scale of appropriate semi-logarithmic paper, using a series of at
seven to eleven laboratories using the Brookfield viscometer model and
least three different temperatures. From the plot, determine the apparent
spindlecombinationavailabletothatlaboratory.Thisencompassedatotal
viscosity at any temperature r
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