Lifetime prediction of solid materials using chemiluminescence to characterise oxidative reactions and model-free simula

1. 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

2. 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

3. Aim: Lifetime prediction Fabian Käser BUA

4. Abstract New approach of lifetime prediction: • experimental data acquisition using Chemiluminescence method • full kinetic analysis • lifetime prediction • conclusion Fabian Käser BUA

5. 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

6. 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

7. 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

8. 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

9. Fields of application 120°C unstabilised 110°C stabilised 100°C 90°C 80°C Fabian Käser BUA

10. 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

11. 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

12. 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

13. Prediction: modulated conditions Fabian Käser BUA

14. 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

15. „… 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