Structure Formation In Solutions Of Rigid Polymers Undergoing A Phase Transition

The development of morphology, when solutions of rigid polymers are transformed from the liquid to the solid state, was studied in two particular cases: coagulation of a monodomain nematic solution and gelation of a dilute isotropic solution. Direct observation of the morphology by electron microscopy (E.M.) was augmented by measurements of small-angle X-ray scattering (SAXS). A theoretical framework for the analysis of SAXS measurements from oriented systems using a slit-collimated incident beam was developed. The first case is realized in the coagulation stage of the spinning process of high performance fibers and films from solutions of rigid macromolecules. A monodomain nematic solution of poly (p-phenylene benzobisthiazole) PBT in polyphosphoric acid PPA undergoes a transition to the solid state by the action of a non solvent (water) . For the second case, gelation of an Isotropic solution of poly (alpha-benzyl- 1-glutamate), induced by a decrease in temperature, was studied. Keywords: Poly (p-phenylenebenzobisthiazole), Morphology, Rigid Rod, Polymers, Thiazoles, Crystals, Solvate, Nematic, Coagulation, Polybenzylglutamate.