THE EFFECT OF ELECTRIC-FIELD ON THE BOND STRENGTH BETWEEN THERMOPLASTIC POLYMERS AND CARBON-FIBERS

A single filament composite (SFC) test was employed to estimate the effects of electric fields and charges - present during the formation of a thermoplastic matrix-carbon fiber system - on interfacial adhesion. Additional electric charge was delivered to the contact region by depositing charged particles of a particulate matrix from a fluidized bed in an electric field. The fiber-matrix bond strength was observed to increase over the whole temperature range tested because the electric forces cause both electrostatic attraction between the fiber and the matrix and significant intensification of the influence of molecular forces through more intimate contact between the components. The effect of additional charge is especially pronounced with a rise in temperature, which is accompanied by an abrupt decrease in molten polymer viscosity. Since interfacial adhesion is controlled by the thinnest matrix layer adjacent to the fiber, it can be much improved by electrostatic deposition of an adhesionally active sublayer before applying the bulk of matrix powder having no charge.