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Pot Life and Curing Monitoring of CASE-Formulations at High Temperatures - 20110 pages
Pot Life and Curing Monitoring of CASE-Formulations at High Temperatures
Pot Life and Curing Monitor for reactive
-
Coatings
Adhesives
Sealants
Elastomers
based on:
- PU formulations
- EP, UP, and MMA
resins
www.format-messtechnik.com
T1[C]
150
Polyurethane (PU) Elastomer
D D‘
3000 10.0
Epoxy (EP) Resin
dielectric polarization
120
surface temperature
T1 master
300 1.00
90
200 -1.00
60
CURING
D master
100 -3.00
30
dielectric polarization / derivative
POT LIFE
400 3.00
surface temperature
dielectric polarization / derivative
dielectric polarization D
core temperature
2400 6.0
surface temperature
1800 2.0
120 120
90 90
POT LIFE
1200 -2.0
60 60
600 -6.0
CURING
30 30
max. cross-linking
0 -5.00
0
0
100
200
300
400
500
400
800
1200
1600
2000
cardboard cylinder
TC
CMD-sensor
temp. sensor
heated base plate
Fig. 5: Cross section of the SubCASE HT test container. The
CMD-sensor is mounted onto the temperature controlled base
plate. The core temperature is measured with a thermocouple.
D
250
0 0
0 -10.0
0
cover plate
T1[C] T2[C]
150 150
surface temperature / core temperature
D D‘
500 5.00
D. JEFFREY GROSS
Eurotech Distributors, Inc.
Northfield, Ohio 44067
USA
T1[C]
150
Methyl Methacrylate (MMA) Resin
| 5,0% cat.
| 3,0% cat.
dielectric polarization
200
120
surface temperature
150
90
100
60
CURING
50
30
0
surface temperature
SubCASE HT
frequencies. The heat release by the polymerization reaction is
recorded as the core temperature by a thermocouple
positioned in the center of the sample. Another temperature
sensor is integrated into the CMD-sensor in order to measure
the contact temperature of the sample and for controlling the
heating power. Starting temperatures as high as 150°C can be
provided by the device. Production near testing conditions can
be achieved by heating the CMD-sensor to any reaction
relevant temperature.
The reactive test material is poured into a cardboard cylinder;
the heated CMD-sensor is located at the bottom of this
cylinder. The test set-up (Fig. 5) is covered by an insulation
hood with a bushing for the thermocouple. The software
SUBCASE continually records the measurement data and
displays them in an online graph. After the test has been
completed, the results are shown in a parameter list as well as
in diagrams. The pot life is defined as a certain value of the
polarization curve. The software SUBCASE calculates the
curing from the dielectric polarization gradient. Due to a
protection foil on the CMD-sensor the cured sample can be
®
removed easily from the device. SubCASE HT can be used in
quality assurance as well as in production control applications.
patents 10252211 and 102004001725
dielectric polarization
®
Standard laboratory methods for testing the reaction profile of
Coatings, Adhesives, Sealants and Elastomers (C.A.S.E.) are
mainly based on mechanical and thermal measurements.
Format Messtechnik GmbH has introduced the device
®
SubCASE for measuring the dielectric properties during
chemical reactions at low and intermediate temperatures. Based
®
on this, the new test device SubCASE HT (Fig. 1) has been
developed, making significant improvements in the
measurement of the pot life and the curing of CASE
®
formulations. SubCASE HT is specially designed for testing
polyurethane formulations (PU) (Fig. 2), epoxy resins (EP)
(Fig. 3), unsaturated polyester resins (UP), and methyl
methacrylate resins (MMA) (Fig. 4) at high temperatures.
®
SubCASE HT combines dielectric polarization measurement
and temperature measurement in one compact laboratory
device. The dielectric polarization reveals the electro-chemical
process during compound formation and cross-linking.
Conclusions can be drawn from this regarding the pot life and
the curing behavior of the material. The heated CMD-sensor
(Curing Monitor Device), introduced by Format Messtechnik
GmbH measures the dielectric features of the reactive
components by applying an alternating voltage of different
ERLAND E. HOFMANN
Format Messtechnik GmbH
D-76187 Karlsruhe
Germany
0
0
1000
2000
3000
4000
5000
time [s]
Fig. 1: Test device SubCASE HT for measuring the pot life
and the curing of Coatings, Adhesives, Sealants and
Elastomers (C.A.S.E.). The reaction profile is determined by
dielectric polarization and temperature measurement.
time [s]
time [s]
Fig. 2: Measurement curves of the dielectric polarization D
and the surface temperature T1 of a polyurethane elastomer.
The D master and the T1 master are margins for QC purpose;
they are provided by the software SUBCASE.
Fig. 3: Measurement curves of the dielectric polarization D,
the surface temperature T1, and the core temperature T2 of an
epoxy (EP) resin. The core temperature is measured by the
thermocouple (TC) in the center of the test sample.
Fig. 4: Comparison of two methyl methacrylate (MMA) resins
with different amount of catalyst. The different curing behavior
is shown in the dielectric polarization curve D, as well as in the
surface temperature curve T1.
