α-relaxation processes in the composites of LC-cellulose derivatives

Molecular relaxation processes in the liquid crystalline cellulose derivatives (CDs) and in their composites were studied by dielectric spectroscopy. The composites, which are anisotropic polymer networks, were prepared by photopolymerization of acrylic acid in the oriented lyotropic solutions of cellulose derivatives. The investigated composites comprise poly(acrylic acid) and hydroxy-, propionyloxy-, hexanoyloxy-, or cyanoethyl-propyl cellulose. In these systems different types of intermolecular interactions are possible: hydrogen bonds, dispersive, or dipolar interactions. The temperature dependences of the alpha-relaxations of CDs can be fitted by the WLF equation, while the beta-relaxation of poly(acrylic acid) is described by an Arrhenius function. The molecular relaxations in the composites are affected in different way by different intermolecular interactions, depending on the chemical structure of CDs. (C) 1998 Elsevier Science B.V. All rights reserved.