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Lifetime prediction of solid materials using chemiluminescence to characterise oxidative reactions and model-free simulation based on experimental data. Fabian Käser Berne University of the Arts - BUA. Oxidation. the major cause of degradation of most organic materials!

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slide1
Lifetime prediction of solid materials using chemiluminescence to characterise oxidative reactions and model-free simulation based on experimental data

Fabian Käser

Berne University of the Arts - BUA

Fabian Käser BUA

oxidation
Oxidation
  • the major cause of degradation of most organic materials!
  • even occurs under ambient environmental conditions

=> Aim: prediction of lifetime expectancy under given, realistic conditions

Fabian Käser BUA

slide3

Aim: Lifetime prediction

Fabian Käser BUA

abstract
Abstract

New approach of lifetime prediction:

  • experimental data acquisition using Chemiluminescence method
  • full kinetic analysis
  • lifetime prediction
  • conclusion

Fabian Käser BUA

experimental data acquisition
Experimental data acquisition

Testing stability by high temperature methods (conventional thermal analysis)

Disadvantage:

  • very high temperature profiles
  • high possibility of phase transitions

=> doubtful correlation to long-term stability (different kinetic behaviour)

Fabian Käser BUA

chemiluminescence cl method
Chemiluminescence CL method
  • light emission resulting from chemical energy
  • relaxation of excited electrons
  • especially during oxidation: 3R=O*
  • mechanism not yet clarified entirely

Fabian Käser BUA

advances of cl method
Advances of CL method
  • very high sensitivity
  • moderate experimental conditions: Texp close to RT
  • CL-signal is not overlapped by other thermal effects
  • excellent baseline stability
  • differentiation of ROOH-decay and mechanism of oxidation
  • acquisition of inhomogeneous character of oxidation reactions
  • implementation of rH% as oxidative factor below 95°C
  • acquisition of oxidationkinetics of most organic materials => numerous applications

Fabian Käser BUA

cl instrumentation
CL instrumentation

oven: precise controll of T

gas exchange facility

optical path: as short as possible

shutter system

detector: PMT photon counting mode

thermoelectrically cooled

%QE @ spectral range of CL

Fabian Käser BUA

fields of application
Fields of application

120°C

unstabilised

110°C

stabilised

100°C

90°C

80°C

Fabian Käser BUA

advanced kinetic analysis
Advanced kinetic analysis

1. baseline optimisation of experimental data

2. isoconversional kinetic analysis:

  • ln (dα / dt) vs. T-1 (Arrhenius based)
  • EA = slope of ln (dα / dt) vs. T-1
  • (α) is constant for every state of reaction αi = isoconversional analysis

Fabian Käser BUA

prediction of reaction progress
Prediction of reaction progress

Description of reaction rate dependent of reaction progress alpha at any given temperature profile

  • isothermal
  • non-isothermal
  • modulated
  • customised climate conditions

Fabian Käser BUA

prediction isothermal conditions
Prediction: isothermal conditions

76.4 years @ 17°C

8.4 years @ 25°C

43.4 years @ 19°C

32.8 years @ 20°C

24.9 years @ 21°C

101.7 years @ 16°C

57.5 years @ 18°C

18.9 years @ 22°C

Fabian Käser BUA

conclusion
Conclusion

Useful approach to predict lifetime and to assess treatment effects in context of conservation-restoration.

Procedure consists of:

  • data acquisition using CL
  • full kinetic analysis
  • prediction of oxidation reaction progress

Fabian Käser BUA

slide15

„… Chemiluminescence which has developed as the most sensitive method for detection of oxidation …“

Popíšil, J. et al., Polymer Degradation and Stability., 82 (2003), 155.

Fabian Käser BUA