Título

WETTING ANGLE MEASUREMENT AND ADHESION PREVISION

Autoria

DARQUECERETTI, E.; CHALENDARBAUDOUX, B. DE; PASCAL, J.; AUCOUTURIER, M.

DARQUECERETTI, E.

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CHALENDARBAUDOUX, B. DE

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PASCAL, J.

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AUCOUTURIER, M.

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DOI

10.5151/2594-5327-49v9-365-370

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Resumo

It is generally admitted that the forces contributing to adhesion include chemical interaction terms between the partners. The evaluation of those terms is of primary importance for the determination of the Dupré work of adhesion, itself necessary to allow the knowledge and eventually the prevision of the behaviour of the stuck assemblies. The chemical interaction terms concern a variety of bond categories, usually classified in two families. The first family refers to "Lifschitz–Van der Waals" (LW) or "dispersive" or "non-polar" interactions. The second is qualified as "acid-base" (a-b) or "donor-acceptor" interactions, and includes the hydrogen bond and all kinds of strong chemical bonds, described either in terms of ionic or covalent bonds, or in terms of electron exchange. More generally, this second family concerns all interactions based on atomic or molecular orbital overlapping. All the interactions define the behaviour of the partner extreme surface, which is, except for the case of polymer diffusion bonding, the fundamental basis for the description of adhesion processes. The paper describes an evaluation and a comparison of the respective influence of the factors controlling the steadiness of adhesive joints for a variety of adhesive assembly systems, between a silicone mastic and various glasses, oxide and polymer substrates. The prevision of initial adhesion is based on wetting angle measurement and complementary methods, as XPS (X Ray Photoelectron Spectroscopy) and FTIR (Fourier Transformed Infrared spectroscopy), of the physicochemical properties of the partner surfaces. The ageing of the silicone mastic and of the interphase is evaluated through mechanical tests, swelling measurements, FTIR and TOF-SIMS (Time-Of-Flight Secondary Ion Mass Spectrometry) analysis. The consequence of substrate ageing on the ageing medium variation is also evaluated. A critical analysis of the validity and reliability of the different investigation methods for the prevision of the behaviour of the stuck assemblies is conducted. Based on the experimental results a mechanism is proposed to explain, and contribute to the prevision, of the compared steadiness of the joints.

Palavras-chave

Adhesion, Wetting angle, Surface interactions, XPS, FTIR