Scientific & Technical Symposium : “Updates in Coatings and Adhesives”

Benzoxazine resins represent a class of thermosetting polymers with distinctive properties making them valuable in various applications. The synthesis of benzoxazine usually involves the combination of formaldehyde, primary amine, and phenolic derivatives. By employing amines or phenolic derivatives bearing additional reactive groups during the synthesis process, it is possible to generate a multifunctional benzoxazine molecule. As a result, the molecular design of benzoxazines can be easily adapted to provide new properties such as self-healing. Other properties of benzoxazines include low surface energy, low water absorption, good adhesion to all kinds of surfaces, and near-zero shrinkage while curing, which are all important for coating applications.
This presentation aims to provide our latest developments in the field of benzoxazine resins as coatings for corrosion protection of metallic substrates, with a focus on the influence of the chemical structure of benzoxazine monomers on the adhesion and corrosion protection of Magnesium alloys.

To evaluate the compatibility between a substrate and a thermoplastic polymer, it is common to calculate their surface energy (dispersive, alkaline, and acid components) in the solid state using the results of contact angle measurements with probe liquids like water, ethylene glycol, and diiodomethane at room temperature. This method provides access to the physical work of adhesion, which is then used to assess adhesion. However, during processing, polymers are in a molten state and at high temperatures, potentially having different surface energies and more complex polymer/substrate interactions due to polymer chain mobility. Therefore, we developed an alternative method that involves directly observing the behavior of thermoplastics above their melting temperature when spreading on surfaces. The physical work of adhesion can then be directly calculated and compared to practical adhesion values obtained by performing mechanical adhesion tests. This presentation will review the recent results we obtained with thermoplastics like PP, PE, and PEEK on inert (glass, steel) or reactive (EPDM rubber) surfaces.

TiO2, or titanium dioxide, is worldwide, the most used white pigment in a variety of applications, eg coatings. Unlike other coloured pigments that generate color by a selective absorption of visible light, TiO2 generates whiteness by the scattering of the visible light. TiO2 is very effective in this, due to a combination of its’ high refractive index and if produced correctly, optimized particle size. Unfortunately TiO2 not only scatters the visible light but also absorbs the UV-light. Unless the TiO2 is specially modified the latter will trigger the degradation of the coating. In this talk we discover how TiO2 is produced to maximize the scattering efficiency and minimize its’ negative effect on the degradation of the coating. Besides optimal  conditions during the production of the TiO2, the composition of a coating will have a significant impact on this scattering efficiency and consequently the hiding power of the coating. In this talk we will explore routes to optimize the scattering efficiency of TiO2 while keeping the other properties in balance.