ALPHA-RELAXATION PROCESSES IN THE COMPOSITES OF LC-CELLULOSE DERIVATIVES

Molecular relaxation processes in the liquid crystalline cellulose der ivatives (CDs) and in their composites were studied by dielectric spec troscopy. The composites, which are anisotropic polymer networks, were prepared by photopolymerization of acrylic acid in the oriented lyotr opic solutions of cellulose derivatives. The investigated composites c omprise poly(acrylic acid) and hydroxy-, propionyloxy-, hexanoyloxy-, or cyanoethyl-propyl cellulose. In these systems different types of in termolecular interactions are possible: hydrogen bonds, dispersive, or dipolar interactions. The temperature dependences of the alpha-relaxa tions of CDs can be fitted by the WLF equation, while the beta-relaxat ion of poly(acrylic acid) is described by an Arrhenius function. The m olecular relaxations in the composites are affected in different way b y different intermolecular interactions, depending on the chemical str ucture of CDs. (C) 1998 Elsevier Science B.V. All rights reserved.