Quantification of copolymer composition (methyl acrylate and itaconic acid) in polyacrylonitrile carbon-fiber precursors by FTIR-spectroscopy

Abstract

Conditions for simple and sensitive FTIR quantitative determination of acrylonitrile, methyl acrylate, and itaconic acid in their copolymer films used as precursor products in carbon-fiber manufacturing are proposed.

Effect of nitrogen pretreatment on the skin‐core structure of thermal oxidative stabilization polyacrylonitrile fibers

“…The peak‐fitting curve of the FTIR spectra of PF5 fiber in the range of 1800–1000 cm −1 was shown in Figure 4(b). The positions and vibration modes of the absorbance peaks of FTIR spectra of PF5 fiber was summarized in Table S1 35,39,45–50 . According to the FTIR spectra, the extent of cyclization and dehydrogenation index of PF0‐PF5 fibers were calculated with Equation () and Equation (), and their changes with pretreatment time were shown in Figure 4(c, d), in which the untreated fiber with a pretreatment time of 0 min was as a blank group.…”

“…Different from the FTIR spectra of pretreated fibers in Figure 4(a), there was a shoulder peak at 1660 cm −1 in FTIR spectra of TOS fibers in Figure 5(a), which corresponded to the conjugated carbonyl groups of oxygen‐containing groups, indicating that oxygen participate in the reaction during TOS process. Figure 5(b) showed the peak‐fitting curve of SF5 fiber in FTIR spectra in the range of 1800–1000 cm −1 , the positions and vibration modes of the absorption peaks in the spectrum was summarized in Table S2 35,39,45–50 . The extent of cyclization was calculated by Equation () and the oxygen content was the absorbance peak intensity of conjugated carbonyl group, which changes were shown in Figure 5(c, d).…”

Effects of Various Transition Metals on the Thermal Oxidative Stabilization of Polyacrylonitrile Nanofibers

“…The C=O peak at 1650 cm -1 represents the conjugated carbonyl group in the acridone ring, whereas the C=O peak at 1700 cm -1 is for the unconjugated carbonyl group in hydronaphthyridine. [10,14] The peak fitting of FTIR by the Gaussian function in the range of 2150-2300 cm -1 is presented in Fig 4 . Two new peaks at 2190 and 2210 cm -1 , identified as β-aminonitrile and conjugated nitrile, respectively, were associated with the transformation of the nitrile peak at 2240 cm -1 (Fig 4). These unsaturated nitrile groups are generated by the termination of the cyclization reaction and dehydrogenation, which can cause structural defects in carbon fiber, such as chain scissions and point defects.…”

“…For example, to decrease the stabilization temperature and/or alleviate the intense exothermic reaction, PAN was copolymerized with itaconic acid (IA), acrylic acid (AA), an ammonium salt of itaconic acid (AIA), guanidinium itaconate (GIA), methyl acrylate (MA), methacrylic acid (MAA), or 2-acrylamido-2methylpropane acid (AMPS). [9][10][11][12][13][14][15][16][17][18] Among these co-monomers, IA resulted in a significant decrease in the stabilization temperature and alleviated the intense exothermic reaction. [14,[16][17][18] Unfortunately, it also decreased the cyclization rate, generating many beta-amino groups and conjugated nitrile groups, which caused point defects in the carbon fiber.…”

Strategies in Precursors and Post Treatments to Strengthen Carbon Nanofibers

“…Another way concerning the precursors is the adding of comonomers to modify the length and structure of polymer chains [111]. Comonomers such as itaconic acid (IA), methyl acrylate (MA), and vinyl acetate (VA) are often added together into PAN solution to produce high molecular weight co-PANs [124][125][126][127][128][129][130]. The comonomers can improve the stabilization efficiency by decreasing the initiation temperature [126], and enhance the mechanical properties [90] and thermal durability of the final CNFs [129].…”