ASTM D3795-00a
(Test Method)Standard Test Method for Thermal Flow, Cure, and Behavior Properties of Pourable Thermosetting Materials by Torque Rheometer
Standard Test Method for Thermal Flow, Cure, and Behavior Properties of Pourable Thermosetting Materials by Torque Rheometer
SCOPE
1.1 This test method covers the apparatus, and a specific test method, including the evaluation of results required for the determination of the thermal flow and cure behavior properties of pourable thermosetting materials.
1.2 This test method can be used:
1.2.1 As a control for the development and production of pourable thermosetting materials and to measure the different properties (for example, melting behavior, cure behavior, etc.) as well as the influence of various additives and fillers in any given formulations, and
1.2.2 Verify the uniformity of different production batches of the same formulation.
1.3 The values are stated in SI units.
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. Specific precautions are given in Section 7.
Note 1--There is no similar or equivalent ISO standard.
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Designation:D3795–00a
Standard Test Method for
Thermal Flow, Cure, and Behavior Properties of Pourable
Thermosetting Materials by Torque Rheometer
This standard is issued under the fixed designation D3795; 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.
1. Scope * 3. Terminology
1.1 Thistestmethodcoverstheapparatus,andaspecifictest 3.1 Definitions of Terms Specific to This Standard—For the
method, including the evaluation of results required for the purpose of this test method, the following definitions apply,
determination of the thermal flow and cure behavior properties (see Fig. 1):
of pourable thermosetting materials. 3.1.1 flow and cure behavior—the flow behavior is repre-
1.2 This test method can be used: sented by the recorded torque curve from the loading peak
1.2.1 As a control for the development and production of (Point t ), to the torque minimum (Point t ).The cure behavior
1 5
pourable thermosetting materials and to measure the different is represented by the recorded torque curve from the torque
properties (for example, melting behavior, cure behavior, etc.) minimum(Point t )tothetorquemaximum(Point t ).Therate
5 4
as well as the influence of various additives and fillers in any of curing is represented by the slope of the torque curve.
given formulations, and 3.1.2 time—the residence time at torque t 3 X, where X is
1.2.2 Verify the uniformity of different production batches a factor (preferably 1.3) is t (s). To determine t , draw a line
v v
of the same formulation. at t 3 X parallel with the time axis. The intersection of this
1.3 The values are stated in SI units. line with the left branch of the curve is t . The intersection of
1.4 This standard does not purport to address all of the this line with the right branch of the curve is t :
safety concerns, if any, associated with its use. It is the
t 5 t 2 t unitsareseconds ~s! (1)
v 3 2
responsibility of the user of this standard to establish appro-
3.1.2.1 Discussion—Depending on the manufacturer of the
priate safety and health practices and determine the applica-
equipment, the software analysis program for the designated
bility of regulatory limitations prior to use. Specific precau-
values in this test method may differ (t , t , etc.).
1 2
tions are given in Section 7.
3.1.2.2 Discussion—Upon agreement between interested
NOTE 1—There is no similar or equivalent ISO standard.
parties, the value of X may be changed and be listed in any
report.
2. Referenced Documents
3.1.3 residence time or duration of plastic life (t − t )—the
2 3
2.1 ASTM Standards:
residence time is represented by a section of the recorded
D792 TestMethodsforDensityandSpecificGravity(Rela-
torque curve in which the molten material causes the lowest
tive Density) of Plastics by Displacement
torque, s.
D883 Terminology Relating to Plastics
3.1.4 total cure time (t − t )—timefromwhenthematerial
4 0
D1898 Practice for Sampling of Plastics
is loaded into the mixer chamber up to complete cure, s.
E691 Practice for Conducting an Interlaboratory Study to
3.1.5 torque:
Determine the Precision of a Test Method
3.1.5.1 initial torque (t )—the initial high torque peak once
material is loaded into the mixer chamber. Sometimes referred
to as the loading peak, Nm (Newton-meters).
ThistestmethodisunderthejurisdictionofASTMCommitteeD20onPlastics
3.1.5.2 minimum torque (t )—thelowestpointonthetorque
and is the direct responsibility of Subcommittee D20.30 on Thermal Properties
curve representing maximum fluxing of material, Nm.
(Section D20.30.08).
Current edition approved July 10, 2000. Published October 2000. Originally
3.1.5.3 final torque or cure peak (t )—the final maximum
published as D3795–79. Last previous edition D3795–00.
torque value representing the final cure of material, Nm.
Annual Book of ASTM Standards, Vol 08.01.
Discontinued; see 1997 Annual Book of ASTM Standards, Vol 08.02.
Annual Book of ASTM Standards, Vol 14.02
*A Summary of Changes section appears at the end of this standard.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
D3795
temperature controlled by a thermostat or electrically with at
least two heating zones (see Note 2).
NOTE 2—Only the results obtained with identical measuring systems
can be compared with one another. In this context, the mixer type, type of
heating/cooling and loading weight used are of decisive importance.
6.1.4 Liquid heated mixers shall be equipped with a circu-
lation pump that has a capacity of at least 24 L/min at a back
pressure of approximately 500 mbars. The heat transfer me-
diumshallbestabilizedsiliconeoil,withamaximumviscosity
of 20 mm /s at 25°C. The oil temperature shall be monitored
by a device which has a resolution of 0.2°C or better.
6.1.5 Electricallyheatedmixerbowlsshallhaveaminimum
of one independent electric controller and a maximum of two
independent electric controllers that utilize modern control
techniquesandalgorithms.Thesecontrollersshallprovideboth
heatingandcoolingcycles.Thetemperaturecontrolensembles
that include the sensor, controller and actuators shall be
NOTE 1—Top curve associated with temperature axis; bottom curve
accurate to within 2.0°C throughout their working range.
associated with torque axis.
Reported values shall have a precision of 0.2°C or better.
FIG. 1 Torque Rheometer Curve
6.1.6 The torque recording ensemble shall be accurate to
0.25% of the reading.
4. Summary of Test Method
6.1.7 For feeding flowable or granular sample materials a
4.1 A sample of thermosetting material is charged into the
loading device shall be used. For feeding other coarse materi-
temperature controlled mixer/measuring head in which the
als,apressureramactuatedmanuallyorpneumaticallyshallbe
material is compacted, melted, cross-linked, hardened, and
used.Theloadingchutehastobemountedontothemixer,with
crushed under constant shear.
a ram and eithera5or2kg weight or with an adjustable
pneumatic cylinder (see Note 2).
5. Significance and Use
6.1.8 For recording of the stock temperature during the
5.1 The continuous recording of torque and temperature
measuring process, the temperature measuring device is
whilegoingthroughthesevariousstagescanbeusedtopredict
mountedfrombelowintothebottomofthemeasuringmixerin
the behavior of the material during processing.
such a way that it penetrates 1.5 mm into the mixer bowl. The
5.2 The torque rheometer test has two important functions.
stock temperature versus time, is recorded simultaneously
First, it is a means to predict flow/viscosity and cure charac-
together with the torque curve.
teristics of pourable thermosetting compounds. For example,
the test provides useful data to predict the processibility of a 6.1.9 Soft Brass Spatula or Stiff Brass Bristle Cleaning Tool.
material in a particular molding method. This information is
also useful to optimize process conditions for a particular
7. Hazards
material such as the minimum pressure to fill a mold and the
7.1 Do not exceed the rated power of the instrument as
time to cure a part.Asecond capability of the test is to provide
damage to the mixer or to the torque rheometer may result.
a graphic record of the batch-to-batch uniformity of the
7.2 Do not attempt to clean or insert objects into the mixer
molding compound.
while it is running.
6. Apparatus
7.3 Use adequate exhausts and safety devices necessary to
meet applicable safety codes.
6.1 Torque Rheometer, with a mixing bowl.
6.1.1 The torque rheometer shall be equipped with a drive 7.4 Use insulated gloves to protect operator from hot mixer
motorwithaload-independentspeedstabilityof 60.5%ofthe surface.
top rotor speed.
7.5 Refer to manufacturers’ operating instructions.
6.1.2 The recording device selected shall be capable of
recording the measurable variables of torque, stock tempera-
8. Sampling
ture, and rotation per minute (RPM) as a function of time.The
8.1 A batch of compound shall be considered as a unit of
rheometer should also be equipped with a real time RPM
manufacture as prepared for shipment and may consist of a
indicator.
manufacturer’s blend of one or more production runs of
6.1.3 For the measurement, a surface hardened laboratory
material.
internal mixer is used, specified by a bowl volume of 25, 30 or
8.2 Suitable methods of sampling shall follow Practice
60 cm , that can be attached to the above mentioned torque
D1898. A 400-g sample will be sufficient for tests required.
rheometer. Either a set of triangular or roller blades shall be
used counter-rotating with a speed ratio of 3:2 (left to right). 8.3 Crushanycompoundinapreformstatetoaparticlesize
(The mixer bowl may be heated with a circulated liquid that would pass through the loading chute.
D3795
9. Sample Selection, Handling and Use for Rheometer three samples are not needed they may be safely returned to
Standardization storage if they have not been opened.
9.2 Calibration—To ensure reliability of this test method, it
9.1 Selection—The selection of the sample should be deter-
is essential that the torque rheometer be calibrated periodically
mined by the use for which it is intended. If it is to be an
usingareferencematerial.Acontrolchartindicatingtheresults
intralaboratory standardization sample, (for example in a
of these calibrations should be kept. Entire equipment calibra-
material compounder’s laboratory), the sample should be
tions shall be done when data from a reference material
chosen to closely approximate the materials expected to be
calibration versus the control chart, causes the instrumentation
tested. (For compounders having a wide range of product
to be suspect.
plasticities it is recommended that one sample for each
9.2.1 Equipment Calibration—The torque, temperature
maximum torque range be available.) For interlaboratory
control, and RPM systems shall be calibrated using national or
standardization,thesampleshouldbeoftheproducttypebeing
international regulatory body traceable standards and proce-
molded.
dures.
9.1.1 Handling:
9.2.2 Record all “as found” measured values versus ac-
9.1.1.1 Once the selection of the sample has been agreed
cepted values before making any attempts at corrective action.
upon among the interested parties it shall be gathered in
All“ as left” measured values should be recorded upon com-
sufficientquantitythatthesupplyofsampleforeachlaboratory
pleting any adjustments.
can be expected to outlast the need to change the mixing head
9.2.3 Upon completion of the calibration, provide a Certifi-
or blades by about 50% of the life of the head or blades. This
cate of Calibration. This document shall include the data
is to avoid running out of standardization standard at the same
values, traceability of each standard used, and a statistical
timeasanequipmentchangetakesplaceontherheometer(see
estimation of the uncertainties associated with each procedure
Note 3).
and standard versus national or international regulatory body
standards.
NOTE 3—The determination for wear of the measuring mixer and
blades shall be measured volumetrically. The equipment manufacturer
10. Procedure
shall provide the procedure and values for the individual measuring
mixers.
10.1 Select a mixer temperature that corresponds to the
mean processing temperature of the material to be tested:
9.1.1.2 Itisrecommendedthatthesamplebebrokenupinto
Material Type (granular) Suggested Temperature, °C
preweighed charges, the charge weight being based on the
specific gravity of the sample and the size of the mixing head
Alkyd 150
Crosslineable polyethylene 145, 175
in use on the respective rheometers. These should be heat-
DAP 150
sealedinindividualpolyethylenepouches.Ifthesamplesareof
Epoxy 150, 175
any compound which has a defined shelf-life, they should be
Phenolic 125, 150
Polyester 150
stored at, or near freezing in order to protect their plasticity
Silicone 140
properties from changing. If the samples have indefinite
Silicone-epoxy 140
shelf-life, they should be stored below the temperature at
10.2 Adjust the required mixer temperature at the bath and
which volatile material could be driven off due to excessive
the circulation thermostat or at the temperature controller for
vapor pressure.
theelectricallyheatedmixer.Conditionthemeasuringmixerat
9.1.1.3 Samples stored in this manner should be allowed a
this temperature until the mixer has reached equilibrium.
full 24-h to reach equilibrium temperature with standard
10.3 Start the torque rheometer before starting the first test
laboratory conditions of 23 6 2°C before removing from
andobtainauniformtemperatureinthesystem.Makesurethat
storage pouches for standardization testing.
the mixing blades are rotating during this time.
9.1.2 Samples should be used to test the standardization of
10.4 Weighthetestchargewithaprecisionof 60.1gandto
therespectiverheometersatagreeduponintervalsofoperation.
an accuracy of 0.5% of the total sample mass for each
It is recommended that the standardization be tested at least
measurement. Depending on the density of the material, the
every 120 h of operation. Operating time is defined not as the
optimum charge for the measuring mixer may vary. Eq 2 is a
total testing time; but rather as the total elapsed time that the
reference for determining a good load charge:
rheometer is powered up. This would be once per week for a
G 50.7 3 V 3 p (2)
full time, five day per week laboratory operation. The samples
should be used two at a time, where the first sample tested will
where:
be used to condition the instrument mixing head and blades,
G = the sample mass, in kilograms,
and the second sample will be used as actual standardization
V = the free mixer volume, in liters,
data.
P = the density of sample material, in kilograms per liter,
9.1.2.1 It is recommended that sample pouches be drawn and (density in accordance with Test Method D792).
from storage five at a time for conditioning to ambient
conditions. The first will be used for rheometer conditioning, The density of the sample material shall be given with an
the second for standardization testing, and the remaining be accuracy of6 0.03 kg/L.
used for additional standardization testing in the event that the 10.5 Start the drive of the torque rheometer and adjust the
instrument needs to be adjusted, or restandardized. If the extra rotor speed to 40 RPM. Charge the running mixer with the
D3795
TABLE 1 Repeatability Results for Thermoset Sa
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