Viscoelastic properties of in situ composite based on ethylene acrylic elastomer (AEM) and liquid crystalline polymer (LCP) blend

Abstract

Viscoelastic properties of in situ ethylene acrylic elastomer composites containing 10 and 20 wt.% of liquid crystalline polymer (LCP) were measured in dynamic mechanical experiments. The results show the significant improvement in the storage modulus of the composites with increasing LCP content. All the composites exhibits a single relaxation, which is glass to rubber transition, observed as a peak in the loss modulus at 1 Hz. The time–temperature superposition principle was applied for the pure ethylene acrylic elastomer (AEM) and its composites, in order to evaluate the changes in the viscoelastic properties of AEM by the addition of LCP. Temperature dependence of the shift factors were described using both the Arrhenius and William–Landel–Ferry (WLF) model at the glass transition region. The activation energies of the shift factors are increases with increasing temperature due to complexicity in the motions of the polymer chains, which is further confirmed by the large activation entropies. The principle of time–temperature superposition is used to study changes in the relaxation spectra of in situ AEM system. It is suggested that the change in the viscoelastic behavior, in the case of LCP reinforced AEM, is due to altered molecular mobility of the polymer chain segments in the vicinity of the LCP phase.