The effect of particle matrix adhesion on the mechanical properties of silica filled cyanate ester composites

The effect of silica and its surface treatment on the mechanical properties of composites was studied as part of the evaluation of cyanate ester matrices as potential electronic encapsulants. Three filler Surface treatments were used, as a qualitative interfacial adhesion scale, in an attempt to gauge the magnitude of interfacial adhesion between untreated filler and the cyanate ester matrix. There was strong interfacial adhesion between matrix and untreated filler. The level of silica content most affected composite modulus and fracture toughness. Filler surface treatment most affected composite strength and fracture toughness/energy. Composite fracture was found to occur via crack pinning and/or crack blunting depending on the strength of adhesion. The composites evaluated were found to possess suitable mechanical properties for potential use as electronic encapsulants.