Poly(acrylonitrile-co-2-methylenesuccinamic acid) as a potential carbon fiber precursor: preparation and stabilization

Abstract

A novel bifunctional comonomer 2-methylenesuccinamic acid (MLA) was synthesized to prepare poly(acrylonitrile-co-2-methylenesuccinamic acid) [P(AN-co-MLA)] copolymers, which can improve the stabilization of polyacrylonitrile significantly as a carbon fiber precursor. The structure and stabilization of P(AN-co-MLA) copolymers with different monomer feed ratios of AN/MLA were characterized by elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Reactivity ratio studies shows that MLA possesses higher reactivity than AN, resulting in higher MLA content in P(AN-co-MLA) copolymers than in the feed. The molecular weight and conversion of copolymer decrease gradually with the increase of MLA content in the feed. Comparing with PAN homopolymer, P(AN-co-MLA) copolymer has two or even three exothermic peaks, and the initial temperature of P(AN-co-MLA) copolymer is ca. 70 C lower than that of PAN, which broadens the exothermic peak. The DH/DT reduces from 34.01 J g À1 C À1 to less than 17.67 J g À1 C À1, confirming that the incorporation of MLA can avoid centralized heat release effectively.In addition, the extent of stabilization increases as the MLA content in P(AN-co-MLA) copolymer increases under the same heat treatment conditions. The activation energy (E a ) calculation shows cyclization E a of P(AN-co-MLA) reduces from ca. 168 kJ mol À1 to ca. 110 kJ mol À1, it is concluded that synthesized comonomer MLA can significantly improve stabilization of PAN, which is conducive to the preparation of high performance carbon fiber.

Preparation, Stabilization and Carbonization of a Novel Polyacrylonitrile-Based Carbon Fiber Precursor

“…As shown in Figure 7d, all of the SI of PAN, P(AN-co-IA), and P(AN-co-AMPS) nanofibers at 195 °C are negative. This might be because the energy supplied by heating is not enough to start the TOS process, but is enough to activate chain segment motion and further improve the recrystallization [19]. As the temperature increased, the SI of P(AN-co-IA) and P(AN-co-AMPS) nanofibers gradually increased.…”

“…In order to solve this problem, several acidic comonomers, such as itaconic acid (IA) [15], acrylic acid (AA) [16], crotonic acid (CA) [17], 2-ethyl hexyl acrylate (EHA) [18], 2-methylenesuccinamic acid (MLA) [19], and vinyl acetate (VA) [20], have ever been incorporated into PAN macromolecular chains to improve the TOS using an ionic cyclization mechanism. Among these comonomers, IA with two carboxylic acid groups is the most efficient comonomer to initiate the cyclization of the nitrile group during the TOS process [21,22].…”

Thermal Analysis and Crystal Structure of Poly(Acrylonitrile-Co-Itaconic Acid) Copolymers Synthesized in Water

“…PAN-IA copolymers exhibit similar curves with a PAN homopolymer. However, the relative intensity of the peak at about 2θ ≈ 16.8 • decreases with the increase of IA content in PAN-IA copolymers, suggesting that the IA comonomer in the PAN macromolecular chains blocks the intermolecular interactions between the nitrile groups [46].…”

Effects of oxygen on the structural evolution of polyacrylonitrile fibers during rapid thermal treatment

“…4b) is identied, indicating oxygen may disturb the transition of the crystalline structure of PAN bers. 7,8 The crystallinity and the crystalline size (L C ) are calculated based on the main diffraction peak at 2q z 17 , as shown in Fig. 5a and b, respectively.…”

“…The stabilization mechanism can be investigated through probing the effects of oxygen on the structural evolution of PAN. 8 It is commonly recognized that the presence of oxygen not only directly affects the oxidation reaction and the cross-linking reaction, but also facilitates the cyclization and dehydrogenation reactions. 9,10 Recently, Liu et al report that the evolutions of chemical and physical structures during thermal oxidative stabilization are simultaneous and interactive, and their transformation mechanism are dissimilar at different temperatures.…”