The birefringence and molecular dynamic of the anisotropic polymer composites obtained by photopolymerisation of the lyotropic liquid-crystalline systems composed of (hydroxypropyl)cellulose and photopolymerisable acrylic acids are studied. Molecular relaxations in such composites were investigated by means of dielectric and mechanical spectroscopies. The molecular relaxation processes, characteristics of pure components, are modified in the composites due to strong intermolecular interactions between the macromolecules. These interactions are also responsible for stabilisation of the structure and the optical properties of the composites. In dielectric spectroscopy two representations were used: temperature dependences of dielectric loss epsilon" and of electric modulus M". This latter one was especially useful in a high temperature range where the ionic conductivity dominates the dielectric response. (C) 2001 Elsevier Science Ltd. All rights reserved.