Light scattering of thermotropic polyester and polysulfone mixtures in solution

A study was made of the static light scattering properties of polymer solutions containing semistiff thermotropic polyester and flexible polysulfone in tetrahydrofuran solvent. These solutions are used as model precursors in the preparation of molecular composites. Light scattering studies of the binary polyester solutions have revealed information on molecular weight, molecular anisotropy, and molecular correlation lengths. The correlation lengths, including orientation and density correlation lengths, were determined by the Stein--Wilson scattering theory for the randomly correlated anisotropic scatters. Both lengths were found to increase with solution concentration, with the density correlation length being greater than the orientation one. Lyotropic behavior was not observed, even when solution concentration exceeded 50 wt.%/vol.%, which is attributed to the intramolecular repulsive interactions and/or a small aspect ratio due to the unusually large molecular diameter. The addition of flexible polysulfone significantly increases the correlation lengths, indicating that the solubility between polyester and polysulfone is low and that the aggregation of anisotropic molecules may occur. Graphs, Phase diagrams. 25 ref.--AA