Heterogeneity of concentrated poly-p-phenyleneterephthalamide solutions

Смирнова, В. Н.; Khanin, Z. S.; Iovleva, M. M.; Prozorova, G. E.; Potemkina, Z. I.; Volokhina, A. V.; Papkov, S. P.

doi:10.1007/bf00548713

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“…It was found that attempts to dissolve PPTA in 96% sulfuric acid or MSA did not lead to stable homogeneous nematic solutions at the concentrations of interest here. For example, solutions of PPTA in 96% sulfuric acid were isotropic at polymer concentrations up to w = 0.12, probably due to intermolecular association, similar to effects reported with PBZT caused by intrusion of moisture to an initially nematic solution. , For higher concentrations up to w = 0.15, the solution contained gray particles, perhaps representing a crystal solvate. − …”

Section: Methodsmentioning

confidence: 54%

“…31,35 For higher concentrations up to w ) 0.15, the solution contained gray particles, perhaps representing a crystal solvate. [36][37][38][39][40][41] After dissolution was complete, the nematic solution was extruded into a rectangular channel, and sealed to prevent contamination by moisture. The cells used in this study have been described elsewhere.…”

Section: Methodsmentioning

confidence: 99%

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Studies on the Texture of Nematic Solutions of Rodlike Polymers. 2. Development and Relaxation of Loop Disclinations

1999

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Features of the development and relaxation of loop defects in the texture of nematic solutions of two rodlike polymers are discussed. Examples given for solutions of poly(1,4-phenylene terephthalamide) and poly(1,4-phenylene-2,6-benzobisthiazole) show the overall similarity of the behavior for these two materials. The development of the mottled texture observed shortly after 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 presented, along with novel effects observed in the interaction of such loops with an external magnetic field.

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