INTERFACIAL ADHESION AND FAILURE MODES IN SINGLE FILAMENT THERMOPLASTIC COMPOSITES

The single filament composite (SFC) test has been used to investigate the adhesion of carbon and glass fibers to thermoplastic matrices. A new modification of the test is proposed, consisting of SFC specimens stretched until the neck formation is complete. This makes the measuring of fiber fragment lengths much easier and allows a wider class of matrices to be investigated. The adhesion between fiber and thermoplastic matrix is strongly dependent on the contact forming conditions. With increased time of thermal treatment, interfacial bonding is improved and the failure mode is changed. In the case of poor fiber-matrix adhesion, interfacial failure occurs. With an increase in interfacial shear strength, the matrix cracks perpendicular to the fiber at the fiber breaks.