The special role of solvents in some systems based on aromatic polyamides

Iovleva, M. M.; Prozorova, G.Ye.; Смирнова, В. Н.; Papkov, S. P.

doi:10.1016/0032-3950(81)90254-9

Cited by 4 publications

(3 citation statements)

References 9 publications

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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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Section: Methodsmentioning

confidence: 54%

Section: Methodsmentioning

confidence: 99%

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

1999

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“…This phenomenon may result in the squeezing out of the solvent from supramolecular particles, an event that is manifested in a decrease in their size. The such phenomenon is revealed for other systems in [83][84][85]. Figure 8 shows the micrographs of HPC solutions after their treatment with the magnetic field.…”

Section: Polymer Rheologymentioning

confidence: 66%

Polymer Rheology

2018

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The results of researches of a magnetic field effect on rheological properties of both paramagnetic, and diamagnetic polymer systems are described. Influence of intensity and the direction of power lines of the magnetic field on the viscosity of magnetic liquids and magnetorheological suspensions is analyzed. Results of theoretical researches of the magnetic field effect on the diamagnetic macromolecule orientation in solutions are discussed. The data on the influence of the magnetic field on rheological parameters of cellulose ether solutions are generalized and analyzed. The rheological parameters are compared with a change of studied system structure under magnetic field. The concentration dependences of viscosity and the sizes of supramolecular particles in solutions are compared. The rheological behavior of systems in a region of phase transitions is considered. Concentration dependences of the viscosity are described by curves with a maximum which concentration corresponds to a phase transition concentration.

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