Modification of polyacrylonitrile precursors for carbon fiber via copolymerization of acrylonitrile with ammonium itaconate

Abstract

Ammonium-modified polyacrylonitrile was prepared by free-radical solution copolymerization of acrylonitrile (AN) with ammonium itaconate (AIA), and then it was spun into precursor fibers in this study. Effects of AIA and itaconic acid on the characteristics of the copolymers and precursor fibers were studied in contrast. It has been found that the ammonium modification could obviously increase the hydrophilicity of the copolymer. And in the spinning processes, modified copolymer can withstand higher total draw-ratio of 12.6 folds, while unmodified copolymer only 8.5 folds. The void volume, fineness, tenacity, and elongation at-break of the ammonium-modified precursors are all improved and enhanced. WAXD test manifested that the modified precursors had higher degree of orientation. DSC test showed that the thermal properties of the modified and unmodified precursor fibers were almost the same.

Effects of comonomer with carboxylic group on stabilization of high molecular weight polyacrylonitrile nanofibrous copolymers

“…The experimental conditions and characteristics of the synthesized polymers are summarized in Table 1. It was noteworthy that the PAN copolymers containing CA synthesized in this study showed higher M v than those synthesized in earlier reports using other comonomers such as methyl acrylate (MA) and IA [11,12], suggesting that the presence of CA comonomer accelerated the growth of polymer chains, leading to higher molecular weight. So far, the large diameter of the polymer fibers has been one of the limitations of carbon fiber strength.…”

Specific features of the copolymerization of acrylonitrile and acrylamide in the presence of low-molecular-mass and polymeric trithiocarbonates and properties of the obtained copolymers

“…Comonomers incorpo rated into the polymer chain destroy its regularity; change the degree of crystallinity of PAN, the rheolog CN ical characteristics of its solutions, and the tensile strength of fibers; promote widening and shifting of the temperature range of PAN cyclization and oxida tion; etc. The magnitude of these changes is deter mined by not only the chemical nature of a comono mer but also its content in the chain [2][3][4][5][6][7][8][9][10]. Thus, additives of itaconic acid, acrylic acid, and meth acrylic acid promote a shift of the cyclization reaction onset toward lower temperatures than that for the AN homopolymer [2][3][4][5], while the presence of methy lacrylate units in the chain has the opposite effect [6,7].…”

“…The magnitude of these changes is deter mined by not only the chemical nature of a comono mer but also its content in the chain [2][3][4][5][6][7][8][9][10]. Thus, additives of itaconic acid, acrylic acid, and meth acrylic acid promote a shift of the cyclization reaction onset toward lower temperatures than that for the AN homopolymer [2][3][4][5], while the presence of methy lacrylate units in the chain has the opposite effect [6,7]. If acrylamide is used as a comonomer, the temper ature range of the cyclization reaction is determined by its content, i.e., the copolymer composition [8,9].…”

Copolymerization kinetics of poly(acrylonitrile‐ran‐2‐ethenyl‐pyridine) and its degradation apparent activation energy

“…1,2 Solution and aqueous suspension are the most common useful techniques. [3][4][5] The solvent-water suspension method is a new and promising technique. It cleverly combines the advantages of solution and those of aqueous suspension.…”