Stuart Lyon - Sustainable coatings by rational design (SusCoRD)

Presentation - pdf

Stuart Lyon^a, Tony Ryan^b, Simon R Gibbon^c
aCorrosion & Protection Centre, School of Materials, The University of Manchester, Manchester, UK
^bDepartment of Chemistry, The University of Sheffield, Sheffield, UK
^cAkzoNobel R&D, Felling, UK

The performance of protective organic coatings is controlled by their physicochemical properties. While many relationships between physicochemical properties and performance have been elucidated over the past decades. The prediction of performance and lifetime of protective coatings is still largely based on testing and formulation knowledge.

SusCoRD, sustainable coatings by rational design, is increasing predictability by combining machine learning, new research to learn new mechanisms of transport, state of the art characterisation equipment and multi-scale modelling approach.  SusCoRD will develop new formulation rules to increase predictability of both the lifetime of coating performance and the coating development process.

Q&A

From  Jordan Petkov : I understand that the underpinning mechanism for paint longevity is in the adhesion and the quality (penetration wise and mechanical) of the paint/film, but what about the development of biofilm that can result in aggressive environment from the outside? Is this something you look at?
Answer: No we are not looking at biofilms. That is important in some circumstances but not particularly important to what we are looking at. The main problem with corrosion protection is that damage occurs underneath the paint and you cannot see it. It is difficult to use clear laquers. We are not interested in what happens on top of the paint. We haven’t talked about UV and chemical stability, but those things are part of the program, but the main driver is corrosion protection.  In the context of external environment, a methanol tanker, the methanol ingress will affect the coating that it makes it more likely to corrode in the future, we need to understand that. Microbial attack on the top of the coating may affect the surface, how the paint forms in the future and we need to capture that.

From  Dr Tolutope Siyanbola : As much as I appreciate your view on focusing on protection of substrate I wouldn't like us to totally strike out aesthetics provided by coatings.
Answer: Appearance is critical, and corrosion damages appearance. You can say that old paints happily allow corrosion to occur and the customer was happy because they couldn’t see the corrosion, but that is not what we are interested.

From  Dr Tolutope Siyanbola : How would you describe coating formulation failure caused by inadequate substrate preparation?
Answer: surface preparation is part of the story. We are trying to understand is what influlences surface preparation may have including surface treatment. Some surface treatment are blasting the surface. We are not interested in mechanical addition. The idea of making a surface more adherent doesn’t really hold true if you measure the pulloff strength of a paint on a polished surfaced and a properly abraded substrate, the pulloff strength is larger in the polished substrate. We are not interested at the moment in mechanical roughness but we are interested in chemical changes in the surface and the chemistry of the surface.

From  Philip Gill :  You report that the Tg of a polymer film varies with thickness.  Have you observed a similar relationship with hardness?   I ask because I’ve observed that the hardness of polymers in a solid filled composite changes around the fillers.  We always assumed it was the filler influencing the polymer.
Answer: if you can give me a method to mesure hardness on a polymer film that is 50 nm thick on a hard surface , I can look into that, but the answer is no, we can’t do that. You can infer that a higher Tg would give a higher nominal hardness but how you measure that.

From  Philip Gill : nano indentation? AFM?
Answer: for nano indentation you have a indentation depth of a few nm that is 10% of the coating thickness, it may be possible using an AFT trying to vibrate or oscillate the surface with and without the coatings, but I think none of these techniques have robust theory behind them.
From Stephenie Burg : The change in Tg vs thickness is my work, I have not looked at hardness yet. Those are possibilities for sure, if and when I manage to get back into the lab with any regularity I will think about it, thanks :)

From  Koray Yıldırım : Do you plan to consider non metal coatings in suscord?
Answer: SusCoRD relates to corrosion protection, so the answer is no, but we believe that the techniques we will develop will be applicable for other surfaces. It has to be said that some of the techniques that we used that were previously developed at Sheffield were for emulsion paints, that have similar problems for reformulation. We take the experience that Sheffield had a long time ago in emulsion type paints and apply it to corrosion protection paints.