Silane adhesion promoters interfacial bonding

The mechanism of chemical adhesion is probably best studied and demonstrated by the use of silanes as adhesion promoters. However, it must be emphasized that the formation of chemical bonds may not be the sole mechanism leading to adhesion. Details of the chemical bonding theory along with other more complex theories that particularly apply to silanes have been reviewed [48,63]. These are the Deformable Layer Hypothesis where the interfacial region allows stress relaxation to occur, the Restrained Layer Hypothesis in which an interphase of intermediate modulus is required for stress transfer, the Reversible Hydrolytic Bonding mechanism which combines the chemical bonding concept with stress relaxation through reversible hydrolysis and condensation reactions. 

After the initial use of Dilulin for making composites was investigated, improvements were attempted by the addition of adhesion promoters [49]. The initial results were interesting because the mechanical properties were not exactly as expected due to the poor interface between the glass fiber matrix and the resin. After this, the adhesion properties were improved by the addition of silane coupling agents. The silane-functionalized norbornenes were able to improve the adhesion to the composite. The final composites were found to be stiffer, which was probably due to a better covalent bond at the interfacial region. They also... 

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