Morphology and structure changes of aromatic copolysulfonamide fibers heat‐drawn at various temperatures

Yu, Jinchao; Wang, Rui; Yang, Chunlei; Chen, Shenghui; Tian, Feng; Wang, Huaping; Zhang, Yumei

doi:10.1002/pi.4747

Cited by 21 publications

(24 citation statements)

References 25 publications

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“…According to eq , the radiuses of microvoids with circles cross section in the prepared fibers are calculated and the results are listed in Table . It demonstrates that the size of microvoids in the cross‐section of the prepared PI fibers exhibit multiorder characters . From Table , the incorporation of DABA monomers leads to a significant decrease in the radius of microvoids before the molar ratio of BIA/DABA reaches 5:5, and PI‐2 has the smallest microvoids, with 14.8, 35.3, and 65.8 Å, implying that homogeneous structure could provide co‐PI fibers more excellent performance.…”

Section: Resultsmentioning

confidence: 84%

Structure and properties of polyimide fibers containing benzimidazole and Amide Units

Yin

Dong

Zhang

et al. 2014

J Polym Sci B Polym Phys

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Co‐polyimide (co‐PI) fibers with outstanding mechanical properties were fabricated via thermal imidization of polyamic acids, derived from a new design of combining the amide and benzimidazole diamine monomers, 4‐amino‐N‐(4‐aminophenyl)benzamide (DABA) and 2‐(4‐aminophenyl)‐5‐aminobenzimidazole (BIA), with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA). The crystalline structure and micromorphology of the prepared co‐PI fibers were investigated by synchrotron wide‐angle X‐ray diffraction (WAXD) and small‐angle X‐ray scattering (SAXS). The two‐dimensional WAXD spectra imply that the co‐PI fibers possess a structure between smectic‐like and three‐dimensionally ordered crystalline phase, and all the obtained fibers are highly oriented along the fiber axis. SAXS patterns exhibit a pair of meridional scattering streaks for the homo‐PI (BPDA/BIA) fiber, suggesting the presence of periodic lamellar structure. The incorporation of DABA into the polymer chains destroyed the lamellar structure but led to smaller size of microvoids upon increasing DABA moiety, based on SAXS analysis. The co‐PI fibers, with the molar ratio of BIA/DABA being 7/3, exhibited the optimum tensile strength and modulus of 1.96 and 108.3 GPa, respectively, attributed to the well‐defined ordered and dense structure. The chemical structure and molecular packing significantly affected the thermal stability of fibers, resulting in the different glass transition temperatures (Tg) from 350 to 380 °C. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 183–191

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Section: Resultsmentioning

confidence: 84%

Structure and properties of polyimide fibers containing benzimidazole and Amide Units

Yin

Dong

Zhang

et al. 2014

J Polym Sci B Polym Phys

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“…The analysis for the microstructural changes of the thermal‐oxidative aging co ‐PSA fibers at large scale was done by SAXS as shown in Figure . According to previous studies, the equatorial streak of small‐angle diffuse scattering for heat‐drawn co ‐PSA fibers is generally attributed to the presence of fibrils elongated along the fiber axis. Therefore, the average length and misorientation angle Bϕ of fibril can be determined by the method of Ruland, as shown in Figure .…”

Section: Resultsmentioning

confidence: 85%

“…The sample‐to‐detector distances for WAXS and SAXS were 236.49 mm and 1,790 mm, respectively. All data analysis (background correction, radial, and azimuthal integration) was carried out using the Xpolar software (Precision works NY) as reported in our previous paper …”

Section: Methodsmentioning

confidence: 99%

“…Hitherto, extensive studies have been carried out on the optimization of spinning process during the formation of PSA fibers in order to improve their performance . In fact, the utility of fibers is also an important issue that worth full concern, because it is likely that while in use, the fibers will be exposed to their relative utility environments (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Performance and structure changes of the aromaticco‐polysulfonamide fibers during thermal‐oxidative aging process

Chen

et al. 2016

J of Applied Polymer Sci

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The changes in performance during thermal-oxidative aging process of the aromatic co-polysulfonamide (co-PSA) fibers over a broad temperature range from 250 8C to 320 8C have been investigated. In addition, the mechanism of thermal-oxidative aging process has been studied by using structural information obtained from the fibers at varying length scales. The results showed that a significant reduction in tensile strength was observed compared with that of initial modulus during aging process. Macroscopically, thermal-oxidative aging mainly causes color changes of fibers and thermally induced macro defects begin to appear only at 320 8C for 100 h. On a micro level, the crystal structure of fibers remained stable and did not show significant changes expect that aging at 320 8C. In addition, thermo-degradation as well as crosslinking has been observed primarily in amorphous region. With the increase of temperature and time duration, the crosslinking became more dominant and crosslinking density increases. Correspondingly, the fibril length decreases due to degradation and then increases due to the formation of crosslinked structures within the fibers. The results suggest that molecular degradation is the main cause of strength loss and the formation of crosslinking structure within the fibers contributes to the retention of modulus and improvement of creep resistance. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44078.

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“…The sample‐to‐detector distance was 114.3 mm calibrating with a LaB 6 standard. Data analysis (background correction, radial and azimuthal integration) was carried out using X‐polar software (Precision Works Inc., NY, USA) as reported previously . The analysis was based on the three‐phase model .…”

Section: Methodsmentioning

confidence: 99%

Creep deformation and its correspondence to the microstructure of different polyester industrial yarns at room temperature

Kang

Liu

et al. 2018

Polymer International

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The room temperature creep behaviors and related microstructural changes of a high‐tenacity (HT) poly(ethylene terephthalate) (PET) industrial yarn and a super‐low‐shrinkage (SLS) PET industrial yarn were investigated and compared by using wide‐angle X‐ray scattering (WAXS), small‐angle X‐ray scattering (SAXS), birefringence measurements and Fourier transform infrared spectroscopy (FTIR) in order to identify their respective underlying creep mechanisms. The crystal structure including crystalline orientation and crystallinity of fibers did not show obvious changes after the creep process, while the amorphous structures varied with creep stress. The HT yarn creep deformation was mainly elastic, and its creep recovery ratio was high. The amorphous orientation, amorphous layer thickness and degree of conformation change from gauche to trans conformers showed a slight increase. The mechanism of this slight change is that the coiled molecular chains are oriented under tensile loading and most of the extended chains are disoriented under offloading in the small amorphous region. By contrast, the SLS yarn underwent plastic creep deformation with a low recovery ratio. After the creep test, the amorphous orientation and lamellar thickness both increased but the crystallinity remained unchanged. The creep mechanism for the SLS yarn is that the molecular chains in the large amorphous domain are easily extended and oriented subjected to tensile loading, while conformation transition from gauche to trans conformers and the formation of irreversible mesophase take place. © 2018 Society of Chemical Industry

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Morphology and structure changes of aromatic copolysulfonamide fibers heat‐drawn at various temperatures

Abstract: The mechanical properties of copolysulfonamide (co‐PSA) fibers did not improve in spite of a substantial improvement in structural perfection at higher drawing temperature.

Cited by 21 publications

References 25 publications

Structure and properties of polyimide fibers containing benzimidazole and Amide Units

Structure and properties of polyimide fibers containing benzimidazole and Amide Units

Performance and structure changes of the aromaticco‐polysulfonamide fibers during thermal‐oxidative aging process

Creep deformation and its correspondence to the microstructure of different polyester industrial yarns at room temperature

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