Nonlinear viscoelasticity of fibre-filled polypropylene melts

Abstract

The paper presents steady-state and dynamic viscoelastic properties of short carbon fibre-filled polypropylene melts (CF/PP) measured by cone-plate rheogoniometer. Storage and loss moduli were analyzed by Fourier series expansion to determine their higher-order terms as the indicators of nonlinear viscoelasticity. CF content affects the viscosity, apparent yield stress, complex viscosity and non-linear character of the properties. In general, the filled PP systems show complex viscoelastic behaviour with some irregularities, e.g. some higher order terms of the storage modulus are negative, which differs from the previously researched filled liquid-crystal polymers.