PAN계 탄소섬유용 신규 전구체의 합성과 분석

Abstract

This study experimentally investigated dicyclohexylammonium 2-cyanoacrylate (CA) as a potential comonomer for polyacrylonitrile (PAN) based carbon fiber precursors. The P(AN-CA) copolymers with different CA contents (0.19 ~ 0.78 mol%) were polymerized using solution polymerization with 2,2′-azobis(isobutyronitrile) (AIBN) as an initiator. The chemical structure and composition of P(AN-CA) copolymers were determined by proton nuclear magnetic resonance spectroscopy(1H-NMR) and elemental analysis, and the copolymer composition was similar to the feeding ratio of the monomers. The effects of CA on the thermal properties of its copolymers were characterized by a differential scanning calorimetry (DSC) under nitrogen or air atmosphere. The DSC curves of P(AN-CA) copolymers under nitrogen atmosphere indicated that the initiation temperature for the cyclization of nitrile groups was reduced to around 235 ℃. The heat release and the activation energy for the cyclization reactions were decreased in comparison with those of PAN homopolymers. On the other hand, under air atmosphere, the P(AN-CA) copolymers with 0.78 mol% CA content showed that the initiation temperature of the cyclization was significantly lowered to 160 ℃. The activation energy value showed 116 kJ/mol, which was smaller than that of the copolymers with 0.82 mol% of itaconic acids (IA). The thermal stability of P(AN-CA) copolymers, which was evidenced by a thermogravimetric analyses (TGA) under air atmosphere, was found higher than PAN homopolymer and similar to P(AN-IA) copolymers. Therefore, this study successfully demonstrated the great potential of P(AN-CA) copolymers as carbon fiber precursors, taking advantages of the initiation temperature-lowering effects of CA comonomers and higher thermal stability of the P(AN-CA) copolymers for the stabilizing processes. Dicyclohexylammonium 2-(carboxymethyl) acrylate [DCMA] was used as a comonomer for polyacrylonitrile (PAN)-based carbon fiber precursors. The P(AN-DCMA) copolymers with different DCMA contents (0.125 - 1 mol %) were synthesized using solution polymerization with 2,2′-azobis(isobutyronitrile) (AIBN) initiator. The molecular structure and ingredient of P(AN-DCMA) copolymers were characterized by nuclear magnetic resonance spectroscopy (NMR), FT-IR, GPC, and viscosity measurement. It was found that the copolymer composition was similar to the feeding ratio of the DCMA comonomer. The effects of DCMA comonomer on the thermal properties of its copolymers were characterized by differential scanning calorimetry (DSC) under nitrogen or air atmosphere, respectively. The DSC curves of P(AN-DCMA) copolymers under nitrogen atmosphere indicated that the initiation temperature for the cyclization of nitrile groups was reduced to around 201 ℃. The heat release and the activation energy for the cyclization reactions were decreased in comparison with those of PAN homopolymers. The thermostability of P(AN-DCMA) copolymers, which was proven by a thermogravimetric analyses (TGA) under air atmosphere, was found to be higher than PAN homopolymer and similar to P(AN-IA) copolymers. These results showed that P(AN-DCMA) copolymer would be a potent candidate as a carbon fiber precursor. Ethyl Cyanoacrylate (ECA) was used as a comonomer for polyacrylonitrile (PAN)-based carbon fiber precursors. The P(AN-ECA) copolymers with different ECA contents (1 – 5 wt%) were synthesized using solution polymerization with 2,2′-azobis(isobutyronitrile) (AIBN) initiator. The molecular structure and ingredient of P(AN- ECA) copolymers were characterized by nuclear magnetic resonance spectroscopy(NMR), FT-IR and GPC. It was found that the copolymer composition was similar to the feeding ratio of the ECA comonomer. The effects of ECA comonomer on the thermal properties of its copolymers were characterized by differential scanning calorimetry (DSC) under nitrogen atmosphere, respectively. The DSC curves of P(AN-ECA) copolymers under nitrogen atmosphere indicated that the initiation temperature for the cyclization of nitrile groups was reduced to around 247 ℃. The heat release and the activation energy for the cyclization reactions were decreased in comparison with those of PAN homopolymers. The thermostability of P(AN-ECA) copolymers, which was proven by a thermogravimetric analyses (TGA) under nitrogen atmosphere, was found to be lower than PAN homopolymer.