DYNAMO-OPTICAL PROPERTIES OF POLY(NAPHTHYLENE OXADIAZOLE)S IN SULFURIC-ACID

Flow birefringence induced in dilute solutions of poly[(1,4-naphthylen e)-2,5-diyl-1,3,4-oxadiazole] and poly[2,6-naphthylene)-2,5-diyl-1,3,4 -oxadiazole] in cone. sulphuric acid has been investigated. The shear optical coefficient was found for these polymers to be approximately d ouble the value of that obtained in the same solvent for poly[(para-ph enylene)-2,5-diyl-1,3,4-oxadiazole]. Rigid-chain behaviour of the poly mers was characterized by hydrodynamic and dynamo-optical parameters e valuated with application of the worm-like chain model and the ''metho d of similar structures''. Change in optical anisotropy of a chain uni t induced by incorporation of naphthylene groups into the main chain h as been evaluated. (C) 1997 Elsevier Science Ltd.