Viscoelastic properties of short fiber filled SBR composites

This paper examines the effects of deformation amplitude, temperature and frequency on the dynamic properties of SBR‐short fiber composites. The presence of the fiber increases the storage modulus at any deformation amplitude. Depending on the nature of the fiber, the linear response zone of the modulus versus deformation either diminishes or disappears. The loss factor tan δ is higher in fiber composites. Although the peaks do not vary in magnitude, they occur at different deformation amplitudes. Temperature increase causes the moduli to decrease, the gradient, however, being less pronounced for fiber composites. The relaxation spectra show a damping peak which correlates to the principal relaxation process in the elastomeric matrix. The temperature at which this peak appears is displaced towards higher values with increasing excitation frequency. This allows the determination of the apparent relaxation activation energy, which is higher in fiber plus adhesive composites (225 – 275 kJ/mol), as compared to the fiber‐free composite (194 kJ/mol), as a consequence of stronger fiber‐matrix interaction.