1. Kinetic parameters of the thermal degradation of polymers by chemiluminescence
Y. Mongbanziama, S. Aeby, S. Roth and P. Brodard
SCS Photochemistry Section Annual Meeting | ETH Zurich |

2. World plastics production
in the world and in Europe
PlasticsEurope (PEMRG) / Consultic

3. European plastics production
Europe ranks 2nd
PlasticsEurope (PEMRG) / Consultic

4. Applications of plastics
1st packaging, 2nd building & construction
PlasticsEurope (PEMRG) / Consultic

5. Aging of polymers
Two main classes of factors influencing the degradation:
physical factors: heat, light…
chemical factors: oxygen, chemicals...
These factors often induce an oxidation:
thermal-oxidation
chemical-oxidation
photo-oxidation
F. Käser, Theory of Chemiluminescence, ACL Instrument AG

6. Thermal-oxidation Russell mechanism (autocatalytic) ketone excited
alcohol
oxygen
ketone
excited
triplet state
F. Käser, Theory of Chemiluminescence, ACL Instrument AG

7.  formation of excited triplet ketone or singlet oxygen
Chemiluminescence
peroxyl radical intermediate:
 formation of excited triplet ketone or singlet oxygen
singlet O2: IR band emission (1270 nm)
triplet ketone: visible range ( nm)
 CHEMILUMINESCENCE

8. Experimental setup
F. Käser, Theory of Chemiluminescence, ACL Instrument AG

9. Isothermal measurements
step 1 of 3 to obtain the kinetic parameters: isothermal measurements
Sorin ILIE, Radu SENETSCU, Polymeric Materials Review on Oxidation,
Stabilization and Evaluation using CL and DSC Methods, TE-VSC (Cern)

10. Numeric fitting
step 2 of 3 to obtain the kinetic parameters: numeric fitting of the CL curve
oxidation mechanism:
J. Rychlý, L. Matisová-Rychlá, D. Jurcák, Chemiluminescence from oxidized polypropylene
during temperature cycling. Polymer Degradation and Stability 2000, 68,

11. Arrhenius
step 3 of 3 to obtain the kinetic parameters: Arrhenius plots
linearization

12. Aging of polyethylene PE
application: water pipes
measured samples: pellets ( mg)
number of measurements: 5x isothermal (150 to 200°C)
atmospheres: pure O2 and air

13. Activation energy of oxidation of PE
results
Oxidative environment
T [°C]
toxidation [h]
A [Hz] Y
k1 [s-1]
k2 [s-1]
Oxygen
200
5.2
1.42·106
7.94·107
1.10·10-3
8.95·10-5
190 12
2.36·105
8.52·109
6.09·10-4
2.84·10-5
180 26
2.34·106
9.48·1014
4.12·10-4
4.26·10-5
170 56
1.86·108
3.02·1018
2.28·10-4
3.82·10-5
150
276
1.14·1024
1.14·1026
6.21·10-5
4.52·10-5
Air 22
1.70·105
2.21·1019
1.90·10-5 50
7.81·107
9.72·1021
2.95·10-4
4.16·10-5
102
4.98·108
6.55·1024
1.64·10-4
2.73·10-5
226
8.89·1012
1.95·1029
8.59·10-5
2.48·10-5
Oxidative environment
Ea [kJ/mol]
A [s-1]
Oxygen
94.4
2.92·107
Air
113.3
1.91·109

14. Estimation of the lifetime of PE
time of maximum oxidation vs. temperature:
 exponential decay!
extrapolation air curve: 70°C  toxidation = 56.4 years

15. Conclusion
Kinetic parameters can be determined by chemiluminescence measurements
Isothermal measurements
Numeric fitting
Arrhenius plots
Non-isothermal prediction of the lifetime is possible
Funding: project PolyAge

16. Thanks!
Yvan Mongbanziama
Samuel Roth
Sandrine Aeby
Pierre Brodard