Rheological characterization of continuous fibre composites in oscillatory shear flow

The anisotropic rheology of a model composite consisting of a temperature-sensitive viscous liquid matrix reinforced by aligned and virtually inextensible fibres of nylon has been studied experimentally using a custom-built linear oscillator. The composite was characterized dynamically both along and transverse to the fibre direction over a wide frequency range and for different fibre volume concentrations. Towards the limit of zero shear the composite was found to exhibit a yield stress. The temperature dependence of the matrix dynamic viscosity was used to study the dependence of the longitudinal and transverse dynamic viscosities of the composite on the dynamic viscosity of the matrix. The dependence of the composite dynamic viscosities on fibre volume concentration is compared with models of the steady shear dependence for aligned fibre systems that have been reported in the literature.