Single-point determination of intrinsic viscosity of wholly aromatic thermotropic copolyesters in 1,1,1,3,3,3-hexafluoro-2-propanol

A series of wholly aromatic thermotropic copolyesters based on 4-hydroxyben zoic acid, hydroquinone, and 2,6-naphthalene dicarboxylic acid were synthes ized by direct melt polymerization with or without different added transest erification catalysts. Nine procedures for calculation of the intrinsic vis cosities from a single viscosity measurement for polymer solutions, includi ng a proposed one, were applied for the thermotropic copolyesters in 1,1,1, 3,3,3-hexafluoro-2-propanol at 30 degreesC. Various forms of the Huggins an d Kraemer equations, singly or combined, yielded intrinsic viscosities that were in good agreement with extrapolated values obtained in the usual mann er from multipoint viscosity measurements over a wide range of concentratio ns. (C) 2001 John Wiley & Sons, Inc.