Hyphenated Thermal, Thermomechanical, and Dielectric ...€¦ · Dielectric Analysis (DEA) basics ... of incoming raw materials Quality Assurance ... a technique for measuring the

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Analyzing & Testing

Hyphenated Thermal, Thermomechanical, and Dielectric Analysis Techniques for Optimizing

and Monitoring Photo-curing Processes

Dr. Pamela ShapiroNETZSCH Instruments North America, LLC(www.netzsch-thermal-analysis.com)

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NETZSCH Group and its Globally Acting Business Units

Analyzing & Testing

The product range consists of instruments for thermal analysis

and for determination of thermophysical properties.

Foundation: 1873 by Thomas and Christian Netzsch in Selb Turnover: about $ 620 million Staff: about 3110 worldwide, about 1100 in Germany Locations: 127 worldwide in 23 countries

Grinding & Dispersing

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.

Pumps & Systems

Comprehensive range of pumps for industrial conveying

tasks – manufacturer of the worldwide known NEMO®

eccentric pumps

Erich NETZSCHGmbH & Co. Holding KG

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Applications of UV Curable Resins

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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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Agenda

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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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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

Thermal Analysis for Investigating UV Curing Process of Adhesives

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Various Thermal Analyzers by NETZSCH Tailored to Different Applications

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Differential Scanning Calorimetry

Thermogravimetry Simultaneous Thermal Analysis

DSC/TGA

Analysis of VolativeSample Amounts

Adiabatc Calorimetry

Dilatometry Thermomechanicaland Dynamic

Mechanical Analysis

Dielectric Analysis Determination of the Thermal Conductivity/Diffusivity

Refractory Testing

DSCDTA

TGA STAQMSFTIR

ARC

DILTMADMA DEA

LFAHFM/GHP

RULHMOR

Met

hods

MethodsUV Curing

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Conclusion

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Agenda

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th

microfurnacesamplesamplecarriergas outlet

controlthermocouple

cont rolthermoc ouple

(2 30°C)

“…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.”

What is DSC?

Heat-Flux DSCPower Compensated DSC

Reference and sample are heated or cooledin the same furnace and are connected bya low resistance heat flow path to equalizetheir temperatures.

Sample and reference are heated or cooledin separate furnaces. Electrical heating power compensates for temperature differences.

H. K. D. H. Bhadeshia, University of Cambridge

FurnaceRefer.Sam ple

T

QPR

.

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Generation of the Measurement Signal

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∆T

= T

R-

TS

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DSC 204 F1 PhoenixSample mass: 14.95 mgCrucible: Al, pierced lidAtmosphere: N2, 40 ml/minHeating rate: 10 K/min

Melting of Indium

125 130 135 140 145 150 155 160 165 170Temperature /°C

0

1

2

3

4

5

6

7

8

DSC /(µV/mg)

93.27 µVs/mg156.6 °C

Area:Onset:

↓ exoDSC 204 F1 Phoenix®

Sample: IndiumSample mass: 14.03 mgHeating rate: 10 K/minAtmosphere: Nitrogen

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Calibration of Sensitivity by Use of Standard Materials such as Indium, Tin, Zinc, Bismuth, …

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µVs

µV/mW

Sensitivitycalibration

µV

t

mJ

t

mW

t

mW

t

mW

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Melting of Indium

DSC 204 F1 Phoenix®

Sample: IndiumSample mass: 14.03 mgHeating rate: 10 K/minAtmosphere: Nitrogen

125 130 135 140 145 150 155 160 165 170Temperature /°C

0.0

0.5

1.0

1.5

2.0

2.5

DSC /(mW/mg)

28.62 J/g156.6 °C

Area:Onset:

↓ exo

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Conclusion

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Agenda

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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

Lightsource

Orifice

2/04/08/0

2/24/48/8Light

guidesFilter

Wave length range:280 / 315 nm … 500 nm

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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

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Temperature range:Crucibles:Various lamp types:

-100 … 200°C for UV curingopen, AlDelolux 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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DSC Coupling to Diode Laser or LED

LASERGLOW Technologiescollimated diode laser system

THORLABS High Power LED

doric High Power LED

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0 2 4 6 8 10 12 14Time /min

-50

-40

-30

-20

-10

0

10

20

30

[4]DSC /(mW/mg)

UV irradiation pulse 2sUV Intensity 1 W/cm²Nitrogen atmosphere

variation of photoinitiator

sample 1

sample 2

sample 3

sample 4

-327.18 J/g -29.51 J/g -11.07 J/g -6.62 J/g -5.04 J/g -4.09 J/g -3.55 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 -3.18 J/g

-360.63 J/g -16.12 J/g -7.51 J/g -5.03 J/g-3.85 J/g -3.17 J/g

-2.75 J/g

-365.17 J/g -15.65 J/g -7.68 J/g-5.27 J/g

-4.13 J/g -3.47 J/g -3.15 J/g

↓ exo

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Curing of UV coatings – variation of photoinitiatorIrradiation Time: 7 x 2 s

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Curing of UV coatings – variation of photoinitiator

86

87

88

89

90

91

92

93

94

95

96

sample 1 sample 2 sample 3 sample 4

Conversion for 1. exposition [%]

350

355

360

365

370

375

380

385

sample 1 sample 2 sample 3 sample 4

total curing enthalpy [J/g]

Conversion for first UV irradiation

Total curing enthalpy

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5.8 6.0 6.2 6.4 6.6 6.8Time /min

-80

-60

-40

-20

0

DSC /(mW/mg)

HDDA

[5] CS_062-3-06-63.sd3_0.md3 DSC

[6] CS_062-3-06-65.sd3_0.md3 DSC

[7] CS_062-3-06-64.sd3_0.md3 DSC

[8] CS_062-3-06-66.sd3_0.md3 DSC

P2: O2PG: N2

P2: O2P1: N2

-170.07 J/g

-377.49 J/g

-267.60 J/g

-387.77 J/g

exo

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1,6 Hexandiol Diacrylate (HDDA)

Influence of the Atmosphere on the Radical UV Curing of an Acrylate Paint

Influence of the oxygen content on the reaction of HDDA

387,8

267,6

170,1

100

200

300

400

-20 0 20 40 60 80 100 120

nitrogen content of the purge gas / %

reac

tion e

nth

alpy

/ J/

g

Linear (error bars: +/- 5%)

pure O2

pure N2

N2/O2 50/50

Oxygen inhibits the reaction

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Comparison of Hg Lamp with Laser - DSC

Formulation: polyethylene glycol diacrylate (PEGDA) + 1% camphorquinone and DMPT (N,N-dimethyl-p-toluidine)

Total curing enthalpy: Lamp: 69 J/g; Laser: 123 J/g

Lamp: 320-500nm, 10 W/cm2; Laser: 447 nm, 0.74 W/cm2

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Conclusion

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Agenda

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What is Dielectric Analysis (DEA)?

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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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The Dielectric Properties

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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°- )

C() = 0 ʹ () (S/d)Capacitance:

() = o ʺ () (S/d)Ion Conductivity:

Ion Viscosity: 1/ ()

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5 10 15 20Time /min

8.0

8.5

9.0

9.5

10.0

10.5

11.0

11.5

12.0

Log ion visc. /Ohm*cm

0.0

0.5

1.0

1.5

d(Log ion visc)/dt /((Ohm*cm)/min)

Log ion visc. (1 Hz)

d(Log ion visc)/dt (1 Hz)

Peak: 2.3 min, 10^7.955 Ohm*cm

End: 7.9 min, 10^11.793 Ohm*cm

Peak: 6.4 min

Cure Monitoring by Dielectric AnalysisCuring of a 2K Epoxy resin (at room temperature)

Ion Viscosity = 1 /

Minimum of ion viscosity => Best flowability / wettability

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Constant ion viscosity=> Final cured state

First derivative of ion viscosity=> Reactivity

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Conclusion

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Agenda

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DEA 288 Epsilon®

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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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DEA 288 Epsilon … for Process Control

Rack-unit for up to 16 channels

Industry Version up to 16 channels Slim Version up to 2 channels

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DEA Sensor Geometry

PARALLEL PLATEELECTRODES

COMB ELECTRODES INTERDIGITATEDCO-PLANAR

BULK FIELD FRINGE FIELD

POLYMER

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Sensors

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IDEX (Interdigitated Electrode) Sensors

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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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0 20 40 60 80 100 120Time /s

5

106

2

5

107

2

5

108

2

5

109

2

5

Ion visc. /Ohm*cm

8.8 s

2.7 s, 0.0085E+08 Ohm*cm

60.0 s, 11E+08 Ohm*cm

11.2 s

3.1 s, 0.0057E+08 Ohm*cm

60.0 s, 33E+08 Ohm*cm

Two Fast UV Curing Cationic Epoxy Systems for Bonding and Fixing During Assembly

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

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Comparison of DSC and DEA for the UV Curing of an Acrylate Adhesive

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4

5

6

789108

2

3

Ion visc. /Ohm*cm

0 5 10 15 20Time /min

-8

-6

-4

-2

0

DSC /(mW/mg)

30

35

40

45

50

Temp. /°C

Main 2011-01-31 18:00 User: Stephan.Knappe

DSC

DEA

-79.46 J/g

-104.3 J/g

-5.279 J/g

-31.48 J/g

-1.44 J/g-1.994 J/g -1.242 J/g -1.082 J/g-1.014 J/g-1.047 J/g

0.1 min, 0.44E+08 Ohm*cm

1.9 min, 0.81E+08 Ohm*cm

5.9 min, 1E+08 Ohm*cm

3.9 min, 0.92E+08 Ohm*cm

7.9 min, 1.1E+08 Ohm*cm

9.9 min, 1.2E+08 Ohm*cm

11.9 min, 1.3E+08 Ohm*cm

13.9 min, 1.4E+08 Ohm*cm

15.9 min, 1.6E+08 Ohm*cm

17.9 min, 1.6E+08 Ohm*cm

19.9 min, 1.8E+08 Ohm*cm

exo

Light intensity: 1 W/cm²IDEX sensor Ten 1s UV pulses every 2min / Frequency of 1000 HzIsothermal temperature: 35°C in air

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Multifrequency-DEA-Measurement on Acrylate-Coating 100, 1000 und 10000 Hz, RT, Irradiation time 3 x 2s

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1.0 1.5 2.0 2.5 3.0 3.5 4.0Time /min

7.0

7.5

8.0

8.5

9.0

9.5

10.0

10.5

11.0


UV Irradiation

UV Irradiation

UV Irradiation

100 Hz

1 kHz10 kHz

10^8.104 Ohm*cm

2.6 min, 10^9.558 Ohm*cm

0.7 min, 10^7.014 Ohm*cm

4.3 min, 10^10.468 Ohm*cm

2.6 min, 10^8.915 Ohm*cm

1.6 min, 10^8.036 Ohm*cm

0.7 min, 10^7.069 Ohm*cm

4.3 min, 10^9.070 Ohm*cm

2.6 min, 10^7.841 Ohm*cm1.6 min, 10^7.716 Ohm*cm

0.7 min, 10^7.085 Ohm*cm

4.3 min, 10^7.875 Ohm*cm

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DEA-Measurement on Acrylate-Coating 10 Hz, RT, Irradiation time 10 x 3s

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5 10 15 20Time /min

7.5

8.0

8.5

9.0

9.5

10.0

10.5






UV Irradiation

Variation of photoinitiator

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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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Conclusion

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Agenda

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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 is the phase shift .

How does the DMA work?

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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.

Mechanical Properties

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Complex Modulus: E* =(t)___

(t)= E´ + i E´´

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Viscoelastic sample

Principle

X1 = irreversible part = E‘‘

X2 = reversible part = E´

force

E´´

E´

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DMA Standard Measuring Modes

Compression /Penetration

Single / Dual Cantilever Shear

Prestress(Static)

Oscillation

Sample

Tension3-Point Bending

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Photo-cured modified acrylates

DELO Photobond 1 and Photobond 2

Tension mode1 HzHeated 3K/min in air

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Conclusion

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Agenda

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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

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UV attachment

DMA Furnacefor UV Curing

For measurements in compression or penetrationmode

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DMA sample holder for UV curing in compression/penetration mode

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Sample holder for UV curing, fused silica window ~15 mm diameter, with compression pushrod

Sample holder with dental resin in instrument, with penetration pushrod

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Comparison of UV cure of 2 different Dental Resins in Compression Mode

1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0Time /min

0

200

400

600

800

1000

1200

E' /MPa

Black: Dental Material aRed: Dental Material b

823.042/04

Compression Mode

Onset: 4.2 min

Onset: 3.5 min

Dental Material aDental Material b

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Summary

All three methods can be used to measure the glass transition

temperature of the resin at different degrees of cure.

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

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Acknowledgments

Dr. Stephan Knappe

Dr. Stephan Smölzer

Dr. Georg Storch

Dr. Tobias Pflock

NETZSCH Gerätebau, GmbH

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Thank you!

[email protected]

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Documents

Hyphenated Thermal, Thermomechanical, and Dielectric ...€¦ · Dielectric Analysis (DEA) basics ... of incoming raw materials Quality Assurance ... a technique for measuring the