ToF‐SIMS and XPS studies of the interaction of silanes and matrix resins with glass surfaces

The interface between glass, glass fibres and epoxy resin in a composite has been studied using time‐of‐flight secondary ion mass spectrometry in static and scanning modes in combination with x‐ray photoelectron spectroscopy. The presence of a multilayer of the polymeric hydrolysed γ‐aminopropyltriethoxysilane (HAPS) on the glass surfaces has been confirmed. After extraction with hot water or toluene only a monomolecular interfacial layer of HAPS is chemically bound to the immediate glass surface through siloxane bonds, leaving the amino groups at the outer surface and available for reaction. It has been demonstrated that this interfacial layer plays an essential role in the coupling reaction between the amino group of the HAPS deposit and the epoxide group of the epoxy resins, diglycidyl ether of bisphenol A or S (DGEBA or DGEBS). These interfacial reactions were complicated by the presence of polydimethylsiloxane and the incorporation of substrate aluminium into the HAPS deposit. The aluminium sites appeared not to be involved in the coupling reaction.