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박도운,류지형,한남구,박원호,정영규 한국섬유공학회 2018 Fibers and polymers Vol.19 No.12
Polyacrylonitrile (PAN)-based copolymers are widely used as a precursor for manufacturing high performance carbon fibers via a series of processes of thermal stabilization, carbonization, and graphitization. We have recently synthesized a series of copolymers with various compositions of acrylonitrile (AN), methyl acrylate (MA) and itaconic acid (IA) by using an efficient aqueous suspension polymerization. In this study, the influences of MA and IA units on thermal stabilization behavior of AN/MA/IA-based terpolymers has been investigated by thermal analyses using DSC and TGA. It was found that the glass transition temperatures (Tg) of AN/MA/IA-based terpolymers with a constant AN content increased with the IA content due to a specific interaction between carboxylic acid and nitrile groups, while the MA unit played a role of lowering Tg of the copolymers owing to the interruption of AN sequence with a strong dipole-dipole interaction. The exothermic peaks of DSC curves as well as the weight loss of TGA/DTG curves under air condition revealed that the IA unit in AN/MA/IA-based terpolymers contributed to accelerate the oxidation reaction especially under air condition and also to slow down the following cyclization and dehydrogenation reactions including isomerization, unlike PAN homopolymer and AN/MA-based bipolymers. On the other hand, the MA unit in AN/MA-based bipolymers and AN/MA/IA-based terpolymers served as a delaying agent on the overall thermal stabilization reactions of oxidation, cyclization and dehydrogenation.
박도운,한남구,류지형,박원호,정영규 한국섬유공학회 2018 Fibers and polymers Vol.19 No.10
We have synthesized a series of copolymers with different compositions of acrylonitrile (AN, 80-100 wt%), methyl acrylate (MA, 4-20 wt%) and itaconic acid (IA, 0-3 wt%) by using an efficient aqueous suspension polymerization, and have investigated the molecular structure and thermal stabilization behavior of PAN homopolymer, AN/MA-based bipolymers, and AN/MA/IA-based terpolymers by adopting 1H/13C-NMR and thermal FT-IR analyses. The viscosity-average molecular weight of the synthesized polymers were measured to be ~263,000 g/mol. The reactivity ratios of AN and MA for all the copolymers were evaluated to be 0.99 and 1.05, respectively. Accordingly, the output compositions of the synthesized copolymers were quite consistent with the input monomer compositions. The 13C NMR analysis revealed that all the synthesized polymers have an atactic chain configuration, regardless of the feed composition. The structural evolutions during the thermal stabilization process of the copolymers in air environment were characterized by monitoring the temperature-dependent changes of characteristic absorbance bands at 2240 cm-1 (C≡N), 1595 cm-1 (C=N) and 1660 cm-1 (C=O) with aid of thermal FT-IR spectroscopy. It was found that the IA unit in the terpolymers accelerated the oxidation and cyclization reactions, unlike the retarding effect of MA unit, and that the onset temperatures of the oxidation reaction of the copolymers with IA unit was lower than that of the cyclization reaction.
폴리케톤 섬유/EPDM 고무의 접착특성에 미치는 폴리도파민 처리의 영향
진다영,박도운,원종성,이승구,Jin, Da Young,Park, Do Un,Won, Jong Sung,Lee, Seung Goo 한국섬유공학회 2015 한국섬유공학회지 Vol.52 No.6
Polyketone fiber can be used for reinforcing mechanical rubber goods (MRG) such as hoses, tire cords, protective gloves, and ropes. However, the reactivity of the surface of polyketone fibers decreases with a high crystallization of the polyketone fiber. Hence, modification of the surface of polyketone fiber is essential for improving the surface functionality and the fiber-matrix interfacial adhesion. In this study, dopamine treatment has been employed for modifying the polyketone fiber surface in order to improve the adhesion between polyketone fiber and ethylene propylene diene monomer (EPDM) rubber. Chemical composition of the modified fiber surface was examined using energy dispersive spectroscopy (EDS), attenuated total reflectance-infrared spectroscopy ((ATR)-IR), and X-ray photoelectron spectroscopy (XPS). Adhesion properties with the rubber were examined by an H-adhesion test. Surface energy and surface morphology were evaluated using contact angle and scanning electron microscopic (SEM) measurements, respectively. A polydopamine layer was formed on the polyketone fiber surface after dopamine treatment, thereby changing the surface energy via the oxidation polymerization of dopamine.