Some Specifics of Defect-Free Poly-(o-aminophenylene)naphthoylenimide Fibers Preparation by Wet Spinning

Skvortsov, I. Yu.; Куличихин, В. Г.; Пономарев, И. И.; Varfolomeeva, Lydia A.; Kuzin, Mikhail S.; Razorenov, D. Yu.; Skupov, Kirill M.

doi:10.3390/ma15030808

Cited by 7 publications

(6 citation statements)

References 21 publications

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“…The samples were prepared in a glove box with a relative humidity of less than 1% to exclude the effect of air humidity on the coagulation process. The method is described in detail in [ 34 ].…”

Section: Methodsmentioning

confidence: 99%

Silica-Filled Polyacrylonitrile Solutions: Rheology, Morphology, Coagulation, and Fiber Spinning

et al. 2022

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The fumed silica influence on the morphology, coagulation processes, and rheological properties of suspensions in dimethyl sulfoxide (DMSO) and polyacrylonitrile (PAN)–DMSO solutions has been studied for the production of composite films and fibers. It has been shown that silica–DMSO concentrated suspensions (24 wt%) form a weak gel with a yield point of about 200 Pa. At concentrations of ~5 wt% and above the dispersions, depending on the shear stress, are pseudoplastic or dilatant liquids. It has been found that the silica addition method into a PAN solution has a significant impact on the aggregates dispersibility and the rheological behavior of the obtained systems. A thixotropy appearance and a sharp increase in the relaxation time were observed for PAN solutions at a SiO2 content of more than 3−5 wt%, which indicates the formation of structures with a gel-like rheological behavior. Upon reaching the critical stress their destruction takes place and the system starts to behave like a viscoelastic liquid. Two spinning methods have been used for preparing fibers: standard wet and mechanotropic. By the mechanotropic method it is possible to achieve a higher draw ratio at spinning and to obtain fibers with better mechanical properties. It is possible to spin fibers from PAN solutions containing up to 15 wt% of silica per polymer with a tensile strength up to 600 MPa.

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Section: Methodsmentioning

confidence: 99%

Silica-Filled Polyacrylonitrile Solutions: Rheology, Morphology, Coagulation, and Fiber Spinning

et al. 2022

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“…The coagulant used was a mixture of DMSO and water with 85:15 ratio of components. The detailed methodology is described in [32].…”

Section: Coagulationmentioning

confidence: 99%

“…To obtain the most homogeneous defect-free fiber, the softness of the coagulant for the PAN solution was selected using the example of a 20% of PAN solution in DMSO. The choice of a lower polymer concentration in the solution is due to the possibility of stable droplet formation in a narrow gap of the measuring cell [32] and to the exclusion of gelling the fiber surface with air moisture to obtain comparable and well-reproducible results.…”

Section: Fibers With Core Enriched With Sio 2 (Wet Spinning)mentioning

confidence: 99%

Polyacrylonitrile Fibers with a Gradient Silica Distribution as Precursors of Carbon-Silicon-Carbide Fibers

et al. 2023

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This study presents preparing and characterization of polyacrylonitrile (PAN) fibers containing various content of tetraethoxysilane (TEOS) incorporated via mutual spinning solution or emulsion using wet and mechanotropic spinning methods. It was shown that the presence of TEOS in dopes does not affect their rheological properties. The coagulation kinetics of complex PAN solution was investigated by optical methods on the solution drop. It was shown that during the interdiffusion process phase separation occurs and TEOS droplets form and move in the middle of the dope’s drop. Mechanotropic spinning induces the TEOS droplets to move to the fiber periphery. The morphology and structure of the fibers obtained were investigated by scanning and transmission electron microscopy, as well as X-ray diffraction methods. It was shown that during fiber spinning stages the transformation of the TEOS drops into solid silica particles takes place as a result of hydrolytic polycondensation. This process can be characterized as the sol-gel synthesis. The formation of nano-sized (3–30 nm) silica particles proceeds without particles aggregation, but in a mode of the distribution gradient along the fiber cross-section leading to the accumulation of the silica particles either in the fiber center (wet spinning) or in the fiber periphery (mechanotropic spinning). The prepared composite fibers were carbonized and according to XRD analysis of carbon fibers, the clear peaks corresponding to SiC were observed. These findings indicate the useful role of TEOS as a precursor agent for both, silica in PAN fibers and silicon carbide in carbon fibers that has potential applications in some advanced materials with high thermal properties.

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“…The gelation of polymer solutions and the sol–gel transition of colloidal systems play a great role in many technological operations, such as fiber spinning, − membrane formation, − and some biological processes. − Consequently, gelation is the subject of attention and interest for fundamental research. Indeed, gelation is a process that combines a complex of various physical phenomena, including phase transitions, diffusion, intermolecular interactions, evolution of rheological properties, etc.…”

Section: Introductionmentioning

confidence: 99%

Role of Small Amounts of Water in the Gelation of Polyacrylonitrile Solutions in Dimethyl Sulfoxide: Rheology, Kinetics, and Mechanism

Skvortsov,

Kuzin,

Gerasimenko

et al. 2024

Macromolecules

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We studied the effect of water addition on the gelation kinetics of polyacrylonitrile (PAN) in dimethyl sulfoxide (DMSO) solutions. The gelation process was considered an evolution of the rheological properties, which were associated with a change in the PAN−DMSO−water system interactions. This approach enabled a detailed investigation of gelation kinetics and phase transformations across varying temperatures, identifying regions associated with solutions, dispersions, thermoreversible, and thermo-irreversible gels. The gelation temperatures of the ternary systems were ascertained using the Winter method. A pivotal element in the gelation process of PAN solutions was identified: the ratio of the unassociated solvent concentration available for PAN solvation relative to the PAN concentration. This specific ratio is instrumental in dictating the formation of nitrile−nitrile interactions. The obtained results will contribute to the understanding of physicochemical approaches to optimizing the composition of gelling polymer solutions in technologies, giving new knowledge to the fields of polymer and materials science.

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Some Specifics of Defect-Free Poly-(o-aminophenylene)naphthoylenimide Fibers Preparation by Wet Spinning

Cited by 7 publications

References 21 publications

Silica-Filled Polyacrylonitrile Solutions: Rheology, Morphology, Coagulation, and Fiber Spinning

Silica-Filled Polyacrylonitrile Solutions: Rheology, Morphology, Coagulation, and Fiber Spinning

Polyacrylonitrile Fibers with a Gradient Silica Distribution as Precursors of Carbon-Silicon-Carbide Fibers

Role of Small Amounts of Water in the Gelation of Polyacrylonitrile Solutions in Dimethyl Sulfoxide: Rheology, Kinetics, and Mechanism

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