Studies on the texture of nematic solutions of rodlike polymers. 2. Development and relaxation of loop disclinations

Features of the development and relaxation of loop defects in the texture o f nematic solutions of two rodlike polymers are discussed. Examples given f or solutions of poly(1,4-phenylene terephthalamide) and poly(1,4-pbenylene- 2,6-benzobisthiazole) show the overall similarity of the behavior for these two materials. The development of the mottled texture observed shortly aft er the solution is extruded into a rectangular capillary, to form a tangle of defect lines which then evolves to form individual loops, is discussed. The differing relaxation dynamics of individual loops observed in the final stages of coarsening near the cell center and close to a surface are prese nted, along with novel effects observed in the interaction of such loops wi th an external magnetic field.