Terpolymers of acrylonitrile, methyl acrylate, and 2‐acrylamido‐2‐methylpropane sulfonic acid for carbon fiber precursor: Effect of comonomers on the thermal stabilization of polyacrylonitrile copolymers

Abstract

Polyacrylonitrile (PAN) copolymers are important precursors for the preparation of high‐performance PAN‐based carbon fibers. In this study, different ratios of P(AN‐co‐AMPS) and P(AN‐co‐MA‐co‐AMPS) were prepared by solution polymerization. The compositional structure, thermal, and crystallization properties of P(AN‐co‐AMPS) and P(AN‐co‐MA‐co‐AMPS) were characterized. The results show that an increase in the AMPS feeding ratio is beneficial for improving the thermal stability and crystallization ability of the PAN copolymer; however, it also reduces the molecular weight of the copolymer and increases the cyclization exothermic peak temperature, which is not conducive to the preparation of high‐performance carbon fibers. This problem is avoided in P(AN‐co‐MA‐co‐AMPS), which maintains its high thermal stability and crystallization properties when appropriate amounts of MA and AMPS are introduced, and P(AN‐co‐MA‐co‐AMPS) has smoother cyclization exothermic rates, lower onset exothermic temperatures and lower peak exothermic temperatures. The structural changes of PAN, P(AN‐co‐MA), and P(AN‐co‐MA‐co‐AMPS) during thermal stabilization were investigated in detail using Fourier‐transform infrared spectroscopy and it was found that P(AN‐co‐MA‐co‐AMPS) formed more stable structures at lower temperatures. Furthermore, when the AN:MA:AMPS mass ratio is 97.5:1.5:1, P(AN‐co‐MA‐co‐AMPS) has the best overall performance. Our results suggest that the P(AN‐co‐MA‐co‐AMPS) has potential as a precursor for carbon fibers.

Microstructural Evolution during Dry-Jet Wet Spinning Postprocessing from Coagulation Bath Fiber to High-Performance Polyacrylonitrile Precursor Fiber

“…Carbon fiber, due to its excellent characteristics of lightweight and high strength, is widely used in lightweight composite materials and plays an irreplaceable role in the fields of national defense, military industry, aerospace, and sports equipment. − Carbon fiber is prepared through thermal stabilization and carbonization of precursor fibers, , with over 90% of commercial carbon fibers still using polyacrylonitrile (PAN) as the precursor material, − although many studies have attempted to use other polymers with linear or cyclic structures to prepare carbon fibers. − Numerous researchers have also been exploring the structure–property relationships of carbon fibers in an attempt to develop high-performance carbon fibers that are increasingly close to theoretical strength and modulus. , Li et al found that the microcrystal size increased with the increase in fiber strength; the size of the micropore also increased, but its quantity decreased . Hao et al analyzed the effect of the microcrystal structure and preferred orientation of different grades of commercial carbon fibers on tensile modulus and found that the tensile modulus of carbon fiber decreased gradually with increasing interlayer spacing and orientation angle, while it rose with the increase of microcrystal size.…”