Tailoring of interfaces in glass fiber reinforced polymer composites: a review

An overview of research on the characterization of interfaces in glass fiber and particulate silica reinforced organic polymers is presented. Descriptions of the chemical and mechanical nature of the siloxane interphases that bond the polymer matrix to the reinforcing phase and their effects on the mechanical properties of fiber reinforced composites are described. While protection of the reinforcement from environmental damage and improvement of adhesion between phases have been well documented, neither the characterization of the properties of the interphase nor its consequences on the durability of a composite material have been definitively resolved. It is generally agreed, however, that synthetically created interphases are often mechanical weak links and a potential source for the initiation of defects in a structure. Recent research has focused on the attainment of monomolecular, reactive surface layers that form strong chemical bonds with both constituents. In this case, the polymeric ‘interphases’ are reduced in dimension to as close to a true ‘interface’ as molecular dimensions allow. Recent work in this area and speculation on the properties required are presented.