FTIR Study of the retardation effect of boric acid on the cyclization reaction of polyacrylonitrile

Abstract

A retardation effect of boric acid on the cyclization reaction of polyacrylonitrile (PAN) was clearly observed by Fourier transform infrared spectroscopy. The Lewis acid nature of boric acid probably accounts for this retardation effect. A quantitative evaluation of this effect was also made, indicating two potential applications, i.e., high temperature stabilization and melt spinning, which are favourable for the cheap and fast fabrication of PAN-based carbon fibers.

Indicators for evaluation of progress in thermal stabilization reactions of polyacrylonitrile fibers

“…Generally, stabilization leads to a reduction in intensity of CN band at 2243 cm −1 , related to linear structure of PAN. In addition, a new band at 1595 cm −1 appears which is attributed to combination effects of CC, CN, and NH links in the aromatic structure of stabilized PAN fibers …”

“…The peaks in the spectrum of the calibration film were compared with the peaks of polystyrene. To evaluate extent of reactions (EOR) during stabilization process, EOR 1 and EOR 2 were calculated using following equations based on calculation of area under characteristic bands …”

An approach towards tailoring interfacial structures and properties of multiphase renewable thermoplastics from lignin–nitrile rubber

“…BA is also known to form hydrogen bonds with nitrile groups and to exhibit Lewis acid-base interactions with the nitrile segments in NBR. 31 In the hardwood lignin/NBR matrix, BA addition to the PEO-modified blend (HSL 5, Fig. 5A) resulted in lower tensile strength and elongation (7.27 MPa, 109% elongation) than that observed in the sample with only PEO (HSL 4).…”