Tendances de recherche dans le domaine des adhésifs à haute performance

Abstract
The high performance adhesives must exhibit good mechanical properties in a wide range of temperatures in different environments for a long time. The aromatic and heterocyclic structures are needed to obtain chemical and thermal resistance. - The linear polymers offer good mechanical properties in term of fracture toughness, but they require high temperature and high pressure for the processing in order to insure good wettability. In addition, the temperature service is limited by the transition. Some examples of linear polyimide will be discussed. - The crosslinkable systems are telechelic aromatic oligomers with end groups such as maleimides, acetylenes or nadimides. These systems offer good wettability, but the cure cycle is more complicated than the one of linear system. The mechanical properties are maintained up to 370°C for a short period of time. - The blend of linear polymer and crosslinkable oligomers were studied in this case of epoxy resins and elastomers and thermoplastics. Recently, it was mentioned that the blend of linear polyimides and crosslinkable bis-maleimide or bis-nadimide improve the properties of each component, and these semi-IPN'S concept will be presented.