1. 24 th ICNTS, Bologna, 1-5 September 2008 Radiation Induced Damage Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Christelle Bergeon 1, Christophe Mavon 1, Franck Berger 1, Zohra Lounis-Mokrani 2, Patrick Delobelle 3, Michel Fromm 1 This paper mainly deals with changes in surface properties of an industrial polymer due to irradiations with gamma photons, electrons and alpha particles. In the second part of the presentation a discussion is presented that aims at comparing the dose (electrons, photons) effects with the fluence (alphas) effects, based on simple track structure theory. 1 : Laboratoire de Chimie-Physique et Rayonnement - Alain Chambaudet (LCPR-AC) UMR CEA E4, Université de Franche-Comté. 16 route de Gray. F-25030 Besançon Cedex 2 : Laboratoire de Dosimétrie, Centre de Recherche Nucléaire d’Alger, BP 399, Alger Gare 16000, Algeria 3 : FEMTO ST-LMARC. UMR 6174. 24, chemin de l’épitaphe. 25030 Besançon cedex France.

2. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage The Polymer Under Study : PP / EPR / HDPE Plastics have become an important material for industrial applications, particularly in the automobile sector. Nowadays, plastics make up on average more than 15% of a vehicles’ weight. Polypropylene is the most commonly used polymer base. This material is the object of this study. Plastic parts are usually coated with paint and/or varnish. Workers in the industry have been trying to improve the coatings’ adherence properties for years. They often try to improve adherence by using a flaming treatment or a plasma technology. What are the effects of ionizing radiations on PP / EPR / HDPE surface and bulk properties ?

3. is a ternary blend : isotactic polypropylene / ethylene-propylene rubber / high density polyethylene 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage The Polymer Under Study : PP / EPR / HDPE Brandon JP, Ph-D Thesis, University of Besançon, N° 245, 1991. Scanning Electron Microscopy of the PP/EPR chemically etched in potassium permanganate in an acid medium isotactic polypropylene polyethylene

4. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Irradiations Electrons : 10 to 10 6 Gy, 2 MeV, In air ( Van de Graaf accelerator, Aerial, Strasbourg, France) Gammas : 10 to 10 6 Gy, 1.17 et 1.33 MeV, In air ( 60 Co source, Alger, Algeria ) Alphas : 10 11 to 10 16 He +.cm -2, 400 keV, Under vacuum (Ion implantation, Lyon, France)    The samples are exposed to electrons and gamma photons in air, as for the alpha particles, irradiation is performed under vacuum ! Electron and gamma photon irradiations can be considered as uniform which is not the case for alpha particles (track structure and dependance on the fluence) The depth at which the incomming particles deposit their energy is very different as well as their stopping power : Radiation Quality Oxygenation

5. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Analytical methods - FT-IR / ATR (Functional groups) - Contact angle (Surface energy, polarity, dispertion, … ) - Nano-Indentation (Young’s modulus & Hardness) Surface properties - Differential Scanning Calorimetry (Melting enthalpy & temperature) Swelling (Swelling ratio and soluble fraction) Bulk properties Irradiated samples have been analysed by means of:

6. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage 1630 cm -1 : vinylic function 1709 cm -1 : Carbonyl bond Results : Surface chemical modifications: FT-IR/ATR spectroscopy Spectrum of the pristine material O2O2 Vacuum Gedde et al., J. Appl. Polym. 1990 A. Chapiro, NIM B. 1988

7. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results (alphas only) : Surface modifications: Contact angle Surface free energy versus fluence There is a correlation between the increase in surface free energy and the loss of hydrogen (vinylic bond formation). Untreated

8. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results : Electrons and photons: Hardness & Young’s Modulus. Whatever electrons or photons were used the results obtained are similar when compared as a function of Dose

9. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results : Nano-indentation curves for alpha & electron - irradiated samples. The visco-elastic behaviour remains The visco-elastic behaviour does not remain after irradiation

10. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results : Swelling for gamma & electron -irradiated samples. Immersion in 1,2 -dichlorobenzene after irradiation at an electron dose of 9. 10 5 Gy. We observe the crosslinking effect.

11. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results : Swelling in hexane for gamma & electron -irradiated samples.

12. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results : Differential Scanning Calorimetry Melting peaks for the two main components of the compound, i.e. PP and HDPE

13. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Results : Differential Scanning Calorimetry

14. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Comparison :

15. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Dose & Fluence : For the ion irradiation, the track overlapping can explain most of the observed effects: See the work by Yamauchi But, is there a way to transform a dose into a fluence or reciprocally ?

16. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Dose - Fluence Relation ? Equivalent Dose Calculation for  = 5.10 13 He +.cm -2 In Polyethylene With electrons and gammas in air, we find D = 10 5 Gy

17. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Dose - Fluence Relation ? The latent track Matlab calculation based on:

18. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Dose - Fluence Relation ? Dose inside the latent track  = 5.10 13 He +.cm -2 To be compared with D = 10 5 Gy !

19. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage Conclusions

20. 24 th ICNTS, Bologna, 1-5 September 2008 Electron, Gamma Photon and Ion Irradiation Effects in PP/EPR/HDPE Radiation Induced Damage