09.12.2013
Analyzing & Testing
Hyphenated Thermal, Thermomechanical, and
Dielectric Analysis Techniques for Optimizing
and Monitoring Photo-curing Processes
Dr. Pamela Shapiro
NETZSCH Instruments North America, LLC
(www.netzsch-thermal-analysis.com)
www.netzsch.com
NETZSCH Group and its Globally Acting
Business Units
Erich NETZSCH
GmbH & Co. Holding KG
Analyzing & Testing
Grinding & Dispersing
Pumps & Systems
The product range consists of
instruments for thermal analysis
and for determination of
thermophysical properties.
Comprehensive product line for
a multitude of tasks in wet and
dry grinding, mixing, de-aeration
and classifying and for the most
different industrial applications.
Comprehensive range of
pumps for industrial conveying
tasks – manufacturer of the
worldwide known NEMO®
eccentric pumps
 Foundation:
 Turnover:
 Staff:
 Locations:
1873 by Thomas and Christian Netzsch in Selb
about $ 620 million
about 3110 worldwide, about 1100 in Germany
127 worldwide in 23 countries
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09.12.2013
Applications of UV Curable Resins
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2
Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Summary
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2
09.12.2013
What is Curing of Polymers?
Curing refers to an increase in polymer length through the
linkage of oligomers and the toughening or hardening of a
polymer material by cross-linking of polymer chains. It can be
promoted by chemical additives, heat, ultraviolet radiation or
an electron beam.
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Thermal Analysis for Investigating
UV Curing Process of Adhesives

When does UV curing start? When is it complete?

What is the optimum power and wavelength?

How does heat, atmosphere, humidity affect the process?

When is the best flow behavior (lowest viscosity)?

What is the reactivity of the resin?

How strong is the cured material?

Where is the glass transition temperature after curing?

Is there a potential for post curing?
 Quality Control (QC) of incoming raw materials
 Quality Assurance (QA) of bonded parts and components
 Research and Development of new formulations
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3
09.12.2013
Various Thermal Analyzers by NETZSCH
Tailored to Different Applications
DSC
DTA
DIL
Dilatometry
Thermogravimetry
Simultaneous Thermal
Analysis
DSC/TGA
Analysis of Volative
Sample Amounts
Adiabatc Calorimetry
TGA
STA
QMS
FTIR
ARC
TMA
DMA
DEA
LFA
HFM/GHP
RUL
HMOR
Determination of the Thermal
Conductivity/Diffusivity
Refractory Testing
UV Curing
Thermomechanical
and Dynamic
Dielectric Analysis
Methods
Methods
Differential Scanning
Calorimetry
Mechanical Analysis
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Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Conclusion
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09.12.2013
What is DSC?
“…a technique for measuring the energy necessary to establish a nearly
zero temperature difference between a substance and an inert reference
material as the two specimens are subjected to identical temperature
regimes in an environment heated or cooled at a controlled rate.”
H. K. D. H. Bhadeshia, University of Cambridge
(2
)
°C
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Furnace
Refer.
Sam ple
.
Q PR
T
Power Compensated DSC
Heat-Flux DSC
Reference and sample are heated or cooled
in the same furnace and are connected by
a low resistance heat flow path to equalize
their temperatures.
Sample and reference are heated or cooled
in separate furnaces. Electrical heating power
compensates for temperature differences.
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∆T = TR - TS
Generation of the Measurement Signal
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09.12.2013
Melting of Indium
DSC /(µV/mg)
↓ exo
DSC 204 F1 Phoenix®
Sample:
Indium
Sample mass: 14.03 mg
Heating rate: 10 K/min
Atmosphere: Nitrogen
8
7
DSC 204 F1 Phoenix
Sample mass: 14.95 mg
Crucible: Al, pierced lid
Atmosphere: N2, 40 ml/min
Heating rate: 10 K/min
6
5
4
3
Area:
93.27 µVs/mg
Onset: 156.6 °C
2
1
0
125
130
135
140
145
Temperature /°C
150
155
160
165
170
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Calibration of Sensitivity by Use of Standard
Materials such as Indium, Tin, Zinc, Bismuth, …
µV/mW
µV
mW
µVs
Sensitivity
calibration
mJ
t
t
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09.12.2013
Melting of Indium
DSC /(mW/mg)
↓ exo
DSC 204 F1 Phoenix®
Sample:
Indium
Sample mass: 14.03 mg
Heating rate: 10 K/min
Atmosphere: Nitrogen
2.5
2.0
1.5
1.0
Area:
28.62 J/g
Onset: 156.6 °C
0.5
0.0
125
130
135
140
145
Temperature /°C
150
155
160
165
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Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Conclusion
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09.12.2013
UV Curing by DSC 204 F1 Phoenix® with
Delolux or OmniCure® Lamps
DSC with OmniCure® S2000
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Operation of a Photo-DSC
2/0
4/0
8/0
Wave length range:
280 / 315 nm … 500 nm
Light
source
Filter
Light
guides
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Orifice
2/2
4/4
8/8
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09.12.2013
Main Features of the Photo-DSC F1 Phoenix®
 Gas-tight DSC cell for defined gas atmosphere
 Three mass flow controllers for precise control of
atmosphere composition
 Use of various commercial lamps

Adjustable and fixed light guides for sample
and reference

Triggered and Controlled by NETZSCH Proteus® software

Automatic Sample Changer for ease of use
Temperature range:
Crucibles:
Various lamp types:
-100 … 200°C for UV curing
open, Al
Delolux 04 or OmniCure S2000 (Hg),
diode laser, LED
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Advanced UV Curing with OmniCure® Lamp


Triggered and Controlled by NETZSCH Proteus® software
Calibration of light intensity with R2000 radiometer
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09.12.2013
DSC Coupling to Diode Laser or LED
THORLABS High Power LED
LASERGLOW Technologies
collimated diode laser system
doric High Power LED
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Curing of UV coatings – variation of photoinitiator
Irradiation Time: 7 x 2 s
DSC /(mW/mg)
[4]
↓ exo
30
-327.18 J/g
-29.51 J/g
-11.07 J/g
-6.62 J/g
-5.04 J/g
-4.09 J/g
-356.84 J/g
-18.18 J/g
-8.34 J/g
-5.64 J/g
-4.27 J/g
-3.65 J/g
20
-3.55 J/g
-3.18 J/g
10
-360.63 J/g
-7.51 J/g
-16.12 J/g
-3.17 J/g
-3.85 J/g
-5.03 J/g
-2.75 J/g
0
-365.17 J/g
-5.27 J/g
-7.68 J/g
-15.65 J/g
-4.13 J/g
-3.15 J/g
-3.47 J/g
-10
-20
sample 1
-30
sample 2
variation of photoinitiator
UV irradiation pulse 2s
UV Intensity 1 W/cm²
Nitrogen atmosphere
sample 3
-40
sample 4
-50
0
2
4
6
Time /min
8
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12
14
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09.12.2013
Curing of UV coatings – variation of photoinitiator
96
95
Conversion for 1. exposition [%]
94
93
92
91
90
89
88
87
Total curing enthalpy
86
sample 1
sample 2
sample 3
sample 4
385
Conversion for first UV irradiation
total curing enthalpy [J/g]
380
375
370
365
360
355
350
sample 1
sample 2
sample 3
sample 4
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Influence of the Atmosphere on the Radical UV
Curing of an Acrylate Paint
DSC /(mW/mg)
 exo
Oxygen inhibits the reaction
0
HDDA
Influence of the oxygen content on the reaction of
HDDA
pure O2
400
P2: O2
PG: N2
-170.07 J/g
-40
N2/O2 50/50
P2: O2
P1: N2
-60
-267.60 J/g
387,8
[5] CS_062-3-06-63.sd3_0.md3
DSC
[6] CS_062-3-06-65.sd3_0.md3
DSC
267,6
[7] CS_062-3-06-64.sd3_0.md3
DSC
[8] CS_062-3-06-66.sd3_0.md3
DSC
300
200
170,1
Linear (error bars: +/- 5%)
100
-20
pure N2
-80
reaction enthalpy / J/g
-20
0
20
40
60
80
100
120
nitrogen content of the purge gas / %
-377.49 J/g
-387.77 J/g
5.8
6.0
6.2
6.4
Time /min
6.6
6.8
1,6 Hexandiol Diacrylate (HDDA)
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09.12.2013
Comparison of Hg Lamp with Laser - DSC
Formulation: polyethylene glycol diacrylate (PEGDA) + 1% camphorquinone and DMPT (N,N-dimethyl-p-toluidine)
Lamp: 320-500nm, 10 W/cm2; Laser: 447 nm, 0.74 W/cm2
Total curing enthalpy: Lamp: 69 J/g; Laser: 123 J/g
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Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Conclusion
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09.12.2013
What is Dielectric Analysis (DEA)?
Dielectric Cure Monitoring and Dielectric Analysis (DEA)
• DEA measures the capacitive and conductive properties of
materials.
• Technique for measuring the changes in dielectric
properties of polymers and curing of resins as a function of
temperature, time, and frequency of the applied alternating
electrical field.
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Fundamentals of DEA
A sinusoidal voltage (excitation, input)
is applied and the resulting current
(output) is measured, along with the
phase shift between voltage and
current.
Dielectric Sensor:
 Alignment of dipoles
 Mobility of ions
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09.12.2013
The Dielectric Properties
 ʹ = Permittivity (Dielectric constant)
A measure of the alignment and number of dipolar groups in a material
 ʺ = Loss factor
A measure of total energy lost due to the work performed aligning
dipoles and moving ions in a material
tan  = Dissipation factor ʺ/ʹ = tan (90°- )
Capacitance:
C() = 0  ʹ () (S/d)
Ion Conductivity:  () = o  ʺ () (S/d)
Ion Viscosity: 1/  ()
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Cure Monitoring by Dielectric Analysis
Curing of a 2K Epoxy resin (at room temperature)
Ion Viscosity  = 1 / 
Log ion visc. /Ohm*cm
d(Log ion visc)/dt /((Ohm*cm)/min)
End: 7.9 min, 10^11.793 Ohm*cm
12.0
11.5
Peak: 6.4 min
1.5
Constant ion viscosity
=> Final cured state
11.0
1.0
10.5
First derivative of ion viscosity
=> Reactivity
10.0
0.5
9.5
9.0
Log ion visc. (1 Hz)
d(Log ion visc)/dt (1 Hz)
0.0
8.5
8.0
Peak: 2.3 min, 10^7.955 Ohm*cm
5
Minimum of ion viscosity
=> Best flowability / wettability
10
Time /min
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14
09.12.2013
Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Conclusion
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DEA 288 Epsilon®
 DEA 288 Lab Version
 8 Dielectric Analyzers for both
DEA signal and temperature
 Main unit with connections to
PC/SD card, furnace/press, UV lamp
 Power Supply with connections to
cooling devices
 Multi-functional Lab Furnace
 Pneumatic Lab Press
 UV Lamp
 Humidity Generator
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09.12.2013
DEA 288 Epsilon … for Process Control


Industry Version up to 16 channels

Slim Version up to 2 channels
Rack-unit for up to 16 channels
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DEA Sensor Geometry
PARALLEL PLATE
ELECTRODES
COMB ELECTRODES
INTERDIGITATED
CO-PLANAR
POLYMER
FRINGE FIELD
BULK FIELD
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09.12.2013
Sensors
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IDEX (Interdigitated Electrode) Sensors
 Very robust and disposable comb sensor in different geometries
 Nickel-plated comb electrodes on polyimide (Kapton) substrate
 Insulated wires (up to 200°C) or ribbon cable (up to 375°C)
115 µm
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09.12.2013
Two Fast UV Curing Cationic Epoxy Systems
for Bonding and Fixing During Assembly
Ion visc. /Ohm*cm
60.0 s, 33E+08 Ohm*cm
5
11.2 s
2
8.8 s
109
60.0 s, 11E+08 Ohm*cm
5
2
108
5
2
107
5
2
2.7 s, 0.0085E+08 Ohm*cm
106
3.1 s, 0.0057E+08 Ohm*cm
5
0
20
DELO Katiobonds
AD610 and AD640
1-Component EP Resins
Sample thicknesses: 200 µm
IDEX Sensors
Irradiation times: 20 s
Intensity: 55-60 mW/cm² UVA
Temperature: 30°C
Frequency: 1000 Hz
40
60
Time /s
80
100
120
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Comparison of DSC and DEA for the UV Curing
of an Acrylate Adhesive
Temp. /°C
Ion visc. /Ohm*cm
DSC /(mW/mg)
 exo
DSC
50
0
-5.279 J/g -1.994 J/g -1.44 J/g -1.242 J/g -1.082 J/g -1.014 J/g-1.047 J/g
3
-31.48 J/g
-2
19.9 min, 1.8E+08 Ohm*cm
-79.46 J/g
2
15.9 min, 1.6E+08 Ohm*cm
45
11.9 min, 1.3E+08 Ohm*cm
-104.3 J/g
-4
7.9 min, 1.1E+08 Ohm*cm
3.9 min, 0.92E+08 Ohm*cm
17.9 min, 1.6E+08 Ohm*cm
13.9 min, 1.4E+08 Ohm*cm
DEA
9.9 min, 1.2E+08 Ohm*cm
5.9 min, 1E+08 Ohm*cm
-6
1.9 min, 0.81E+08 Ohm*cm
108
9
8
7
6
-8
0.1 min, 0.44E+08 Ohm*cm
0
Main
2011-01-31 18:00
5
User: Stephan.Knappe
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35
5
Light intensity: 1 W/cm²
IDEX sensor
Ten 1s UV pulses every 2min / Frequency of 1000 Hz
Isothermal temperature: 35°C in air
10
Time /min
40
4
30
20
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09.12.2013
Multifrequency-DEA-Measurement on AcrylateCoating 100, 1000 und 10000 Hz, RT, Irradiation time 3 x 2s
Log ion visc. /Ohm*cm
11.0
UV Irradiation
4.3 min, 10^10.468 Ohm*cm
10.5
10.0
2.6 min, 10^9.558 Ohm*cm
UV Irradiation
9.5
4.3 min, 10^9.070 Ohm*cm
9.0
8.5
2.6 min, 10^8.915 Ohm*cm
UV Irradiation
10^8.104 Ohm*cm
1.6 min, 10^8.036 Ohm*cm
8.0
7.5
7.0
1.6 min, 10^7.716 Ohm*cm
0.7 min, 10^7.085 Ohm*cm
4.3 min, 10^7.875 Ohm*cm
2.6 min, 10^7.841 Ohm*cm
100 Hz
1 kHz
10 kHz
0.7 min, 10^7.069 Ohm*cm
0.7 min, 10^7.014 Ohm*cm
1.0
1.5
2.0
2.5
Time /min
3.0
3.5
4.0
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DEA-Measurement on Acrylate-Coating
10 Hz, RT, Irradiation time 10 x 3s
UV Irradiation
Log ion visc. /Ohm*cm
10.5
10.0
9.5
9.0
8.5
Variation of photoinitiator
8.0
Log ion visc. (10 Hz)
Log ion visc. (10 Hz)
7.5
Log ion visc. (10 Hz)
Log ion visc. (10 Hz)
5
10
Time /min
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20
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09.12.2013
Comparison of Hg Arc Lamp with Laser - DEA
Irradiance:
Lamp 10 W/cm2
Laser: 0.74 W/cm2
Formulation: polyethylene glycol diacrylate (PEGDA) + 1% camphorquinone and DMPT (N,N-dimethyl-p-toluidine)
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Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Conclusion
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09.12.2013
How does the DMA work?
A sinusoidal force (stress, σ) is applied to the sample. This results is a
sinusoidal response (deformation or strain, ε). Most materials – especially
polymers – exhibit a “viscoelastic behavior”. They posses both elastic (stiff like a
spring) and viscous (damping effect) characteristics. Due to this viscoelastic
behavior, the corresponding stress and strain curves are shifted. The deviation
40
is the phase shift .
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Mechanical Properties
Complex Modulus: E* =
(t)
___
(t)
= E´ + i E´´
Storage modulus (E´):
represents the material‘s stiffness and is
proportional to the maximum stored work
during stress.
Loss modulus (E´´) :
is proportional to the work dissipated from
the material during stress. It is a measure
for the oscillation energy transformed into
heat.
Loss factor (tan):
represents the mechanic damping or inner
friction of a viscoelastic system.
41
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09.12.2013
Principle
Viscoelastic sample
X1 = irreversible part = E‘‘
force
E´´
E´
X2 = reversible part = E´
42
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DMA Standard Measuring Modes
Single / Dual Cantilever
Compression /
Penetration
Shear
Prestress
(Static)
Oscillation
Sample
3-Point Bending
Tension
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09.12.2013
Photo-cured modified acrylates
Tension mode
1 Hz
Heated 3K/min in air
DELO Photobond 1 and Photobond 2
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Agenda
 Introduction to UV Curing and Thermal Analysis
 Differential Scanning Calorimetry (DSC) basics
 NETZSCH Photo-DSC instrumentation and application
examples
 Dielectric Analysis (DEA) basics
 NETZSCH Photo-DEA instrumentation and application
examples
 Dynamic Mechanical Analysis (DMA) basics
 NETZSCH Photo-DMA instrumentation and application
examples
 Conclusion
www.netzsch.com
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09.12.2013
DMA 242 E Artemis

Wide temperature range (-170°C to 600°C)
heating rate 0.01 to 20K/min

Large dynamic and static forces (up to 24 N)
increased resolution up to 8 N

Frequency range of 0.01 to 100Hz
46
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UV attachment
DMA Furnace
for UV Curing
For measurements in
compression or penetration
mode
47
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09.12.2013
DMA sample holder for UV curing in
compression/penetration mode
Sample holder for UV curing, fused silica
window ~15 mm diameter, with compression
pushrod
Sample holder with dental resin in
instrument, with penetration
pushrod
48
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Comparison of UV cure of 2 different
Dental Resins in Compression Mode
E' /MPa
1200
Black:
a
Dental Dental
MaterialMaterial
a
Dental
Material
b
Red:
Dental
Material
b
1000
800
600
400
Compression Mode
Onset: 3.5 min
200
0
Onset: 4.2 min
823.042/04
1.0
2.0
3.0
4.0
5.0
6.0
Time /min
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7.0
8.0
9.0
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09.12.2013
Summary

Coupling UV-curing with DSC, DEA, and DMA measurements enables the
determination of curing kinetics, degree of cure, and end of cure.
Additionally:

DSC measures the enthalpy of the reaction and degree of sample heating
by the radiation.

DEA is most sensitive to small changes in the degree of cure.

DMA measures the strength of the resin at the end of cure

All three methods can be used to measure the glass transition
temperature of the resin at different degrees of cure.
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50
Acknowledgments
Dr. Stephan Knappe
Dr. Stephan Smölzer
NETZSCH Gerätebau, GmbH
Dr. Georg Storch
Dr. Tobias Pflock
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09.12.2013
Thank you!
pamela.shapiro@netzsch.com
www.netzsch-thermal-analysis.com
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