‘SAUVEUR‘1 st June 2006Fabian Käser BUA 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

‘SAUVEUR‘1 st June 2006Fabian Käser BUA 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

‘SAUVEUR‘1 st June 2006Fabian Käser BUA Aim: Lifetime prediction

‘SAUVEUR‘1 st June 2006Fabian Käser BUA Abstract New approach of lifetime prediction: -experimental data acquisition using Chemiluminescence method -full kinetic analysis -lifetime prediction  conclusion

‘SAUVEUR‘1 st June 2006Fabian Käser BUA 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)

1 st June 2006Fabian Käser BUA ‘SAUVEUR‘ Chemiluminescence CL method -light emission resulting from chemical energy -relaxation of excited electrons -especially during oxidation: 3 R=O* -mechanism not yet clarified entirely

1 st June 2006Fabian Käser BUA ‘SAUVEUR‘ Advances of CL method very high sensitivity moderate experimental conditions: T exp 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

1 st June 2006Fabian Käser BUA ‘SAUVEUR‘ 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 spectral range of CL

1 st June 2006Fabian Käser BUA ‘SAUVEUR‘ Fields of application 120°C 110°C 100°C 90°C 80°C unstabilised stabilised

‘SAUVEUR‘1 st June 2006Fabian Käser BUA Advanced kinetic analysis 1. baseline optimisation of experimental data 2. isoconversional kinetic analysis: -ln (dα / dt) vs. T -1 (Arrhenius based) -E A = slope of ln (dα / dt) vs. T -1 -  (α) is constant for every state of reaction α i = isoconversional analysis

‘SAUVEUR‘1 st June 2006Fabian Käser BUA 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

‘SAUVEUR‘1 st June 2006Fabian Käser BUA °C °C °C °C °C °C °C °C Prediction: isothermal conditions

‘SAUVEUR‘1 st June 2006Fabian Käser BUA Prediction: modulated conditions

‘SAUVEUR‘1 st June 2006Fabian Käser BUA 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

1 st June 2006Fabian Käser BUA ‘SAUVEUR‘ „… Chemiluminescence which has developed as the most sensitive method for detection of oxidation …“ Popíšil, J. et al., Polymer Degradation and Stability., 82 (2003), 155.