On 22th decembre 2017, Lucie Bres has defended her thesis. Awarded by University of Toulouse III – Paul Sabatier, her work was supervised by both LAPLACE laboratory (CNRS/INP-ENSEEIHT/UT3 Paul Sabatier), the GEET doctoral school, and IRT Saint Exupéry.
The high quality and the relevance of Lucie’s thesis contributed to get significant results as a part of SURFINNOV project.
THESIS SUBJECT
“Interaction between a cold atmospheric pressure plasma and industrial thermoplastic surfaces: relevance to surface activation”
About her thesis
Carbon Fiber Reinforced Polymer (CFRP) using thermoplastic polymer matrices as Poly-EtherEtherKetone (PEEK) for example, are increasingly being used in structural engineering due to their light weight coupled with good mechanical properties. In aeronautic industry, the adhesive bonding of these composites is often required. However, their low surface energy motivates the development of robust and reliable surface activation treatments aiming at increasing the surface reactivity before painting. For this reason, we have used an atmospheric pressure plasma torch developed by AcXys Technologies®. It is a remote plasma, well known to be an effective process to improve surface reactivity without deterioration of the bulk matrix properties. This easily implementable technology attracts many industries looking for a cost-effective and eco-friendly surface activation process. The aim of this work is to contribute to the understanding of plasma activation mechanisms leading to a greater and a more durable adhesion between PEEK matrix and an industrial painting.
This study provides some insight into the effects of process parameters (device power, distance between nozzle and substrate, etc) on adhesion improvement. Mechanisms which are attributed to it are investigated by means of three point bending and crosscut adhesion standard tests. Results are discussed with respect to surface properties characterized by wettability measurements including acid-base approach, X-ray Photoelectrons Spectroscopy and Atomic Force Microscopy.
In order to facilitate industrialization of atmospheric pressure remote plasma as surface activation technique, this study proposes a new approach aiming at allowing a better and more equitable comparison between atmospheric pressure plasma processes. This comparison is made through the “plasma dose” expression, similar to the one commonly used in Corona process. It is applicable for one plasma gas and accounts for both received energy and interaction time of the post-discharge with the surface. Mechanisms assigned to improvement of adhesion will be more appreciated and their characterization will contribute to a greater definition of industrial surface preparation range by remote plasma.
SURFINNOV Project
Development of corrosion protection solutions for light alloys, improvement of tribological properties of the titanium and improvement of surface treatments versus the temperature.
Jury
- M. Nicolas GHERARDI – CNRS-LAPLACE – PhD Advisor
- M. Bertrand RIVES – IRT Saint Exupéry/STELIA – Co-Supervisor
- Mme Françoise MASSINES – Promes-CNRS – Rapporteur
- M. Patrick CHOQIET – Luxembourg Institute of Science and Technology – Rapporteur
- Mme Aline BARBERA – Airbus Helicopters – Examiner
- M. Nicolas NAUDE – Univ. Paul Sabatier – LAPLACE – Invited
- M. Thierry SINDZINGRE – AcXys Technologies – Invited
PUBLICATIONS
L. Bres, N. Gherardi, N. Naude and B. Rives: “Remote atmospheric pressure plasma for improving acid-base surface properties of PEEK polymer: relevance to coating adhesion”. Expert’Labs, Fuveau (France). 2016
Abstract : Our study focuses on a remote atmospheric pressure plasma for the improvement of polymer surface reactivity. From the perspective of linking surface modifications to adhesives performances, wettability measurements are made using two models (Owens-Wendt-Rabel-Kaelble and Van Oss-Good-Chaudhury). This study is a contribution to correlate wettability with adhesion results obtained with three-point bending test. Acid-base properties of the treated polymeric surfaces are discussed according to the Lewis’s theory.
L. Bres, N. Naude, N. Gherardi and B. Rives: “Cold Atmospheric Pressure Plasma treatment of PEEK and PEKK based composite for aeronautical purposes”. PSE 2016 (15th International Conference on Plasma Surface Engineering), Garmisch-Partenkirchen (Germany). 2016
L. Bres, B. Rives : “Cold atmospheric pressure plasma activation for CFRP before paint application”. Airbus Structure Days, Madrid (Spain). 2015