DYNAMIC-MECHANICAL BEHAVIOR OF A SIDE-CHAIN LIQUID-CRYSTALLINE POLYACRYLATE

The phenomenology of the alpha- and p-relaxation processes in an amorp hous and a crystallized specimen of a side-chain LC polyacrylate, base d on the azobenzene mesogenic unit, was investigated by thermal and dy namic mechanical methods. The activation energy of the beta relaxation of the crystallized sample is equal to that of the amorphous sample. The alpha-transition process of the amorphous sample was described by the WLF equation. In contrast, the Lu-relaxation behavior of the amorp hous part of the semicrystalline sample was described by a double Arrh enius law broken at T = T-g. This peculiar behavior has been tentative ly related to the decrease of the motion characteristic length of the macromolecules confined in the multidomain structure of the semicrysta lline state. (C) 1996 John Wiley & Sons, Inc.