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

Abstract

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.

Structural evolutions during creep deformation of polyester industrial fiber via in situ synchrotron small-angle X-ray scattering/wide-angle X-ray scattering

“…The sample-to-detector distances for WAXS and SAXS were 150 mm and 1770 mm, respectively. Data analysis (background correction, radical, and azimuthal integration) were carried out using the X-polar software (Precision works NY, USA) as reported in our previous papers [21][22][23][24].…”

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

“…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 .…”

The fire retardant properties and pyrolysis mechanism of polysulfonamide (PSA) fibers

“…During the aging process, the tensile strength of PSA decreased rapidly compared with its initial modulus. 13 Zhu et al. investigated the thermal degradation kinetics of PSA fiber by thermogravimetric analysis (TGA) at four heating rates (5, 10, 15, and 20℃/min), and the results obtained by the Coats–Redfern method showed that the conversion model of PSA was a deceleration mechanism.…”

“…Yu et al investigated the mechanical performance of PSA fibers under thermal-oxidative aging from 250 C to 320 C. During the aging process, the tensile strength of PSA decreased rapidly compared with its initial modulus. 13 Zhu et al investigated the thermal degradation kinetics of PSA fiber by thermogravimetric analysis (TGA) at four heating rates (5,10,15, and 20 C/ min), and the results obtained by the Coats-Redfern method showed that the conversion model of PSA was a deceleration mechanism. 14 In practice, as an inherent fire retardant fiber, the fire retardant properties under real fire scenarios are of significant importance.…”