Effects of Drawing and Heat-Treatment Conditions on the Structure and Mechanical Properties of Polyhydroxyamide and Polybenzoxazole Fibers

강찬솔,지민호,여문진,백두현 한국섬유공학회 2018 Fibers and polymers Vol.19 No.8

We report the preparation of polybenzoxazole (PBO) fiber from polyhydroxyamide (PHA) precursor fiber which is free from strong acid such as polyphosphoric acid. We prepared the PHA fibers with different spin-draw ratios (SDRs) using a wet-spinning method and the PBO fibers with an SDR of 3.5 (SDR-3.5 PBO fibers) were prepared by various heattreatment temperatures, and investigated their morphology, crystalline structure, and mechanical properties. The simultaneous thermogravimetric analysis-mass spectrometry (STA-MS) and field-emission scanning electron microscopy (FE-SEM) results confirmed that the diameter of the SDR-3.5 PBO fiber was much smaller than that of the SDR-3.5 PHA fiber, due to the release of water during the thermal cyclization reaction which forms the PBO structure. The wide-angle Xray diffraction (WAXD) pattern of the SDR-3.5 PBO fiber heat-treated at 350 oC (SDR-3.5 PBO 350 fiber) showed two peaks, at 2θ=14.83 o and 24.38 o, and the diffraction angles dropped with increasing heat-treatment temperature. In addition, the initial modulus and tensile strength of the SDR-3.5 PBO fiber heat-treated at 550 oC (SDR-3.5 PBO 550 fiber) were found to be 19.1 GPa and 449.2 MPa, which were much higher than those of the SDR-3.5 PHA fiber, 9.3 GPa and 227.0 MPa, respectively.

탄소재료 전구체로 사용가능한 헤테로 고리방향족 고분자의 탄화거동에 대한 열처리 온도의 영향

강찬솔 한국섬유공학회 2020 한국섬유공학회지 Vol.57 No.3

In this study, carbonized polyhydroxyamide (C-PHA) and polybenzoxazole (CPBO) precursors were prepared from PHA and PBO polymers, respectively, through heattreatment of 600−1200 °C for 1 h under nitrogen atmosphere. Fourier-transform infrared spectroscopy (FT-IR), elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), thermographic and mass spectrometry, wide-angle X-ray diffraction, Raman spectroscopy, transmission electron microscopy, and electrical conductivity test were performed to monitor the changes in the chemical structures of the two precursors. From FT-IR, EA, and XPS results, PHA and PBO polymers were directly converted to C-PHA and C-PBO precursors, respectively, above 800 °C without undergoing the oxidative stabilization process. The maximum carbonization yield of the carbonized precursors was 1.36 times (68.3%) higher than that of the commercialized PAN-based carbon fiber (50%). High-resolution transmission electron microscopy images revealed a small amount (~30%) of turbostratic graphite structure around an external area in the C-PBO precursor at 1000 °C.

하수처리 슬러지를 활용한 TiO2 From Sludge (TFS) 광촉매 제조 및 특성 분석

강찬솔,여우석,나병찬,정호진,장호종,김종규 한국섬유공학회 2023 한국섬유공학회지 Vol.60 No.2

In this study, TFS was manufactured using sewage sludge generated by applyingTiCl4 to a total phosphorus treatment facility. Physical and chemical characteristics of TFSwere analyzed to determine whether the manufactured TFS was successfully manufacturedas TiO2 photocatalyst. As a result of operating, the total phosphorus treatment facilityby applying TiCl4 as a flocculent, the total phosphorus concentration in the sewage wasreduced from 0.3 mg/l to 0.03 mg/l, recording a over 90% total phosphorus reduction efficiency. In the physical analysis, the crystal structure of the TFS observed an anatase crystalstructure. The element composition ratio of TFS is 84.05%, so it is determined that TFS canbe used in place of TiO2. The average particle size of TFS is 12.5 μm and the BET is 40.8 m2/g,which is not significantly different from the existing TiO2, P-25. In the NO reduction experiment,which is the cause of fine dust, conducted to determine TFS photocatalytic ability,there is no significant difference in NO reduction efficiency from the existing widely usedTiO2, P-25. Therefore, TFS can reduce the amount of carbon dioxide generated by makingsludge generated in total phosphorus treatment facilities eco-friendly resources, which cancontribute to realizing carbon neutrality. In addition, TFS is considered an eco-friendlymaterial that is excellent economically and environmentally because it can efficientlyreduce NO, which is the cause of fine dust.

폴리히드록시아미드 섬유의 제조와 열처리에 따른 구조-물성 상관관계(I) -다양한 고화조건에 따른 고화거동-

강찬솔,지민호,백두현,Kang, Chan Sol,Jee, Min Ho,Baik, Doo Hyun 한국섬유공학회 2013 한국섬유공학회지 Vol.50 No.4

Polyhydroxyamide (PHA) was synthesized using low temperature solution polymerization of 3,3'-dihydroxybenzidine (DHB) and isophthaloyl chloride (IPC) in N,N-dimethylacetamide (DMAc). In order to study wet-spinning of PHA fibers, the diffusion property of DMAc in various coagulants and the effect of coagulation bath temperature were evaluated. The initial diffusion rate of DMAc, and the SEM images and mechanical properties of PHA fibers, demonstrated that the coagulation in ethanol at $20^{\circ}C$ was the most optimal among all the conditions examined. The tensile strength and initial modulus of PHA fibers increased, while its breaking strain decreased with increasing spin draw ratio (SDR). The wide-angle X-ray diffraction (WAXD) experiment revealed that the crystallinity of PHA fibers increased with increasing SDR. The process-structure-property relationship among PHA fibers under various coagulation conditions was also investigated.

친환경 Carbon Eating Concrete 제조를 위한 나노버블 이산화탄소 용해 배합수 제조 기술 개발 및 최적화

강찬솔,장호종,박정준,여우석,김주현,김덕현,김종규 한국수처리학회 2023 한국수처리학회지 Vol.31 No.3

The construction sector generates a significant volume of domestic carbon dioxide(CO2) emissions, with most of the CO2 emitted during the cement manufacturing process. In an attempt to reduce the levels of CO2, technology that sequesters CO2 by injecting it as a gas into the concrete during the mixing and/or curing process has been developed as a means for permanent CO2 storage. However, the current range of applications for this strategy and the CO2 storage efficiency of concrete are low. In order to overcome these limitations, we developed a technology that can dissolve CO2 in water under normal conditions (i.e., without the need for pressure) using nanobubbles less than 200 nm in diameter. As a result of injecting CO2 into normal water and nanobubble water over 5 h, the maximum dissolved concentration of CO2 was observed for ordinary water, while 2,012 mg/L of CO2 was dissolved in the nanobubble water. How ever, when CO2 was injected into the nanobubble water under optimal conditions as determined using RSM-CCD analysis (i.e., a water temperature of 10°C, a pH of 11, a reaction time of 6 h , and a stirring speed of 20 RPM), 2,756 mg/L of CO2 was dissolved. As a result,it was demonstrated that CO2 can be successfully dissolved in water using nanobubbles under normal conditions. If nanobubble water in which CO2 has been dissolved is applied to other fields, CO2 levels can be reduced in an eco-friendly way, contributing to the realization of carbon-neutral goals. .

리튬황전지 양극재용 탄소 재료 전구체 나노웹의 탄화거동 연구

강찬솔 한국섬유공학회 2023 한국섬유공학회지 Vol.60 No.3

In this study, the carbonized polybenzoxazole (C-PBO) nano-webs were madefrom PBO nano-web via the electro-spun polyhydroxyamide (PHA) nano-web by heatingtemperatures of 800-1200 oC for 1h under N2 atmosphere, respectively. XPS, EA, FT-IR, TGA,Raman spectra, electrical conductivity, and HR-TEM were used to observe the carbonizationbehavior in C-PBO nano-webs. XPS, EA, and FT-IR results displayed that PBO nano-webdirectly converted to C-PBO nano-webs above 800 °C without the stabilization process. TGA results showed that the C-PBO nano-webs have excellent thermal stability at hightemperatures (~750 oC) and can undergo the carbonization process to yield turbostraticgraphite structure. Raman spectra observed the ID/IG of C-PBO nano-webs was improvedon increasing the carbonization temperature.

Synthesis and Thermal Properties of Polyhydroxyamide Copolymer and Its Derivatives as Precursors of Polybenzoxazoles

강찬솔,백두현 한국고분자학회 2015 한국고분자학회 학술대회 연구논문 초록집 Vol.2015 No.10

폴리히드록시아미드 공중합체의 열 고리화 거동에 대한 연구

강찬솔,민재호,남민우,서무송,지민호,백두현,Kang, Chan Sol,Min, Jae Ho,Nam, Min Woo,Seo, Moo Song,Jee, Min Ho,Baik, Doo Hyun 한국섬유공학회 2016 한국섬유공학회지 Vol.53 No.5

A series of polyhydroxyamide copolymers (Co-PHAs) containing 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (BAHHFP) and/or bis(3-amino-4-hydroxyphenyl) sulfone (BAHS) were synthesized via a low-temperature solution polymerization method. The synthesized Co-PHAs were characterized by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). All the Co-PHAs were found to be soluble in organic solvents with or without LiCl. The chemical structures of the Co-PHAs were identified using FT-IR spectroscopic analysis. The DSC and TGA results showed that the inclusion of BAHHFP and/or BAHS in the Co-PHAs reduced the thermal cyclization temperatures as compared to DHB, which is due to the difference in the rotational energy of the diamine monomers.

Preparation and Characterization of Thermally Stable Polybenzoxazole Copolymer Films Fabricated from Their Precursors

강찬솔,백두현 한국섬유공학회 2019 Fibers and polymers Vol.20 No.12

The polyhydroxyamide copolymers (F-PHAs) were synthesized by low-temperature solution polycondensation of 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAHHFP) and/or 3,3'-dihydroxybenzidine (DHB) with terephthaloylchloride (TPC) in N,N-dimethylacetamide (DMAc) with the aid of lithium chloride (LiCl). A series of polybenzoxazolecopolymer (F-PBO) films were fabricated via an efficient solution-casting and thermal-treatment technique, using theirprecursors (F-PHA films) with different BAHHFP fractions (25-100 mol%). The solubility results show that F-PHAs withhigher BAHHFP content (≥75 mol%) are readily soluble in anhydrous DMAc and N-methyl-2-pyrrolidinone (NMP) withoutLiCl at room temperature. Differential scanning calorimetry (DSC) indicates that the thermal cyclization temperature of theF-PHA films decreases with increasing BAHHFP content. Thermogravimetric analysis (TGA) reveals that the F-PHA and FPBOfilms are well prepared and completely converted. The UV-visible spectra indicate that the F-75-PBO film (BAHHFPcontent: 75 mol%) has reasonable transparency, with 84.9 % transmittance at 600 nm and 397-nm UV cut-off wavelength. Italso has lower coefficient of thermal expansion (CTE) (48 ppm/oC) and water absorption (WA) values (0.14 %). TheBAHHFP as diamine component provides the final F-PBO film with desirable properties, e.g., flexibility, thermal stability,transparency, and WA values.

MWNT와 Graphite 전도성 나노입자를 함유한 폴리우레탄 하이브리드 나노복합체의 기계적 물성 및 전기적 특성 평가

강찬솔,지민호,백두현,Kang, Chan Sol,Jee, Min Ho,Baik, Doo Hyun 한국섬유공학회 2012 한국섬유공학회지 Vol.49 No.3

The synergistic effects of multi-walled carbon nanotubes (MWNT) and graphite on the structural features and mechanical and electrical properties of polyurethane (PU) nanocomposites were investigated as functions of filler content. SEM images of the PU/hybrid nanocomposite exhibit that the MWNTs and graphite are dispersed well in the PU matrix and form an interconnected network structure. Accordingly, the tensile strength and strain-at-break of the PU/hybrid nanocomposites were much higher than those of the PU/MWNT and PU/graphite nanocomposites at the same filler content. In addition, it is found that the PU/hybrid nanocomposite containing 1.25 wt% MWNTs and 1.25 wt% graphite shows the electrical conductivity of $1.2{\times}10^{-4}S/cm$, which is higher by three orders than that of PU/graphite nanocomposite containing 20.0 wt% graphite. The highly improved mechanical and electrical properties of the PU/hybrid nanocomposite are thought to be due to the interconnected network structure of MWNTs and graphite in the PU matrix.