• Composites Research
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• 제28권5호
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• pp.265-269
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• 2015

최근에 각광을 받고 있는 섬유강화 복합재료, 웨어러블 전자소자, 그리고 전자파 차폐재료 같은 다양한 응용분야에 적용하기 위해서, 높은 기계적 전기적 특성을 갖는 그래핀 섬유를 대량으로 생산하는 일은 산업적으로 매우 의미가 있다. 본 연구에서는 다이-아민 그룹으로 화학적 치환 된 산화 그래핀을 습식 방사 공정을 통하여 섬유로 제조하는 효율적인 공정을 개발하였다. 다이-아민 그룹으로 치환된 산화 그래핀은 합성이 용이하고 수용액에서 분산성이 매우 좋으며, 저렴한 비용으로 대량 생산이 가능한 장점을 가지고 있다. 이렇게 제조된 아민-치환 그래핀 섬유는 산화 그래핀 섬유와 비교해서 높은 기계적, 전기적 특성을 보이기 때문에 웨어러블 전자 소자에 응용이 기대된다.

• 한국염색가공학회지
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• 제32권2호
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• pp.111-120
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• 2020

In this study, lignin/chlorinated poly(vinyl chloride)(CPVC) blended fibers have been produced for the development of low-cost carbon fiber. Carbon fiber manufacturing was accomplished through stabilization and carbonization process. The lignin/CPVC blended fibers were prepared by wet spinning method. Dimethylacetamid e(DMAc) and cychlohexanone in a ratio of 5:1(wt%) was employed as co-solvent. The ratio of lignin/CPVC was prepared at 0/10, 1/9, 2/8, 3/7, 4/6, and 5/5(wt%). The spinning solution was extruded at a rate of 0.1 to 0.4ml/min according to the blending ratio. The speed of the rollers was the same for all ratios(draw ratio=1). Analysis of fiber cross-section by scanning eletron microscopy(SEM) showed that as the lignin ratio increased in the same coagulation bath and distilled water, the pore size of the spinning fiber decreased. Therefore, the highest tensile strength of the blending fibers was 6.3±1.2MPa at the 5/5 ratio. The carbon fiber also showed the best tensile strength of 120.78±2.43MPa at 5/5 ratio.

• Carbon letters
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• 제11권3호
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• pp.176-183
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• 2010

PAN precursor fibers were produced via wet-spinning process, and effects of polymerization and spinning processes, especially the stretching process, were investigated on mechanical properties and micro-morphologies of precursor fibers. An increase in molecular weight, dope solid and densification and a decrease in surface defects were possible by controlling polymerization temperature, the number of heating rollers for densification and the jet stretch ratio, which improved the mechanical properties of precursor fibers. The curves for strength, modulus, tensile power and diameter as a function of stretch ratio can be divided into three stages: steady change area, little change area and sudden change area. With the increase of stretch ratio, the fiber diameter became smaller, the degree of crystallization increased and the structure of precursor fibers became compact and homogeneous, which resulted in the increase of strength, modulus and tensile power of precursor fibers. Empirical relationship between fiber strength and stretch ratio was studied by using the sub-cluster statistical theory. It was successfully predicted when the strengths were 0.8 GPa and 1.0 GPa under a certain technical condition, the corresponding stretch ratio of the fiber were 11.16 and 12.83 respectively.

• Membrane and Water Treatment
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• 제1권3호
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• pp.215-230
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• 2010

Poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, hollow fiber membranes were prepared by the dry/wet spinning technique using different polyethylene glycol (PEG) concentrations as non-solvent additive in the dope solution. Two different PEG concentrations (3 and 5 wt.%). The morphology and structural characteristics of the hollow fiber membranes were studied by means of optical microscopy, scanning electron microscopy, atomic force microscopy (AFM) and void volume fraction. The experimental permeate flux and the salt (NaCl) rejection factor were determined using direct contact membrane distillation (DCMD) process. An increase of the PEG content in the spinning solution resulted in a faster coagulation of the PVDF-HFP copolymer and a transition of the cross-section internal layer structure from a sponge-type structure to a finger-type structure. Pore size, nodule size and roughness parameters of both the internal and external hollow fiber surfaces were determined by AFM. It was observed that both the pore size and roughness of the internal surface of the hollow fibers enhanced with increasing the PEG concentration, whereas no change was observed at the outer surface. The void volume fraction increased with the increase of the PEG content in the spinning solution resulting in a higher DCMD flux and a smaller salt rejection factor.

• Composites Research
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• 제26권2호
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• pp.123-128
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• 2013

PVDF(polyvinylidene fluoride) 섬유는 습식방사방법을 적용하여 제조하였다. PVDF 분자 내 압전 특성과 밀접한 관련을 갖는 ${\beta}$형태의 결정 함량을 높이기 위하여, 본 연구에서는 습식방사 된 섬유에 1단계 연신, 2단계 어닐링 공정으로 구성하여 후 처리를 도입하였다. 후 처리는 PVDF 고분자의 유리전이 온도($T_g$)와 용융온도($T_m$) 사이의 온도범위에서 진행하여, 최대의 ${\beta}$형태 결정을 생성 할 수 있는 열처리 조건을 최적화 하였다. 제조된 PVDF 섬유 내 분자 배향 특성과 결정 구조를 확인하기 위하여 적외선 분광 광도계(FT-IR)와 X선 회절 분석기(XRD)를 이용하여 분석하였으며, 전자현미경(SEM)을 통하여 섬유의 표면을 관찰하여 섬유의 평균직경을 확인하였다. 분석 결과, 후 처리 공정이 PVDF 결정 구조의 영향을 미치며, ${\beta}$형태의 결정 비율을 증가시킨다는 것을 확인하였다. 더불어 ${\beta}$형태 결정 향상으로 인해 기계적 강도가 증가되었으며, 압전 특성 향상까지 기대할 수 있었다.

• Carbon letters
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• 제13권3호
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• pp.182-186
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• 2012

A new model and resultant equation for the coagulation of acrylonitrile monomers in precipitation polymerization are suggested in consideration of the surface tension (${\gamma}$) and cohesive energy density ($E_{CED}$). The equation was proven to be quite favorable by considering figure fittings from known surface tensions and cohesive energy densities of certain organic solvents. The relationship between scale value of surface tension (${\gamma}$/M) and cohesive energy density of monomers can be obtained by changing the coagulation bath component for effective precipitation polymerization of acrylonitrile in wet spinning.

• 한국염색가공학회지
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• 제17권5호
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• pp.13-19
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• 2005

Dyeing and fastness properties of direct spun type PET microfiber fabrics have been investigated. The dye uptake of finer microfibers commenced at lower temperatures and showed faster rate of dye uptake. The build-up and wet fastness properties of disperse dyes on finer microfbers were relatively poor since the more dye was needed to achieve a given depth of shade due to the large surface area.

• 한국막학회:학술대회논문집
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• 한국막학회 1997년도 춘계 총회 및 학술발표회
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• pp.34-35
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• 1997

The phase inversion is a significant phenomena in the preparation of membranes and wet spinning. In both these processes, a viscous dope solution is precipitated in a nonsolvent bath and a porous structure is formed under certain conditions. Such structure could have been considered as a diffusion controlled process. The membrane formation of the polymer solution includes both phase separation and gelation. We have studied the influence of variables on the final structure and tried to control the porosity and ultrafiltration(UF) performance of the polyacrylonitrile(PAN) and its copolymer.

• 한국염색가공학회지
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• 제11권3호
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• pp.32-40
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• 1999

Chitosan fiber was prepared by wet spinning with various draw ratio. Chitosan fiber was coated with f-carboxymethyl keratein(SCMK) by extruding chitosan solution into 1 M NaOH solution containing 1% SCMK. Among three chitosan used in this study(chitosans of 5 cps, 50 cps, 100 cps), 50 cps chitosan gave the best tenacity and optimum concentration was 5%. SCMK coating increased the tenacity of chitosan fiber. Regardless of SCMK coating, tenacity and elongation of both chitosan fibers were increased with the increase of draw ratio. Chitosan fiber showed antimicrobial activity against Staphyloccus aureus showing 66∼72% of bacteria reduction rates. On the other hand, chitosan fiber coated with SCMK didn't show any antimicrobial activity.

• 한국염색가공학회지
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• 제20권2호
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• pp.1-8
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• 2008

Regenerated composite fibers are prepared from solution(styela clava tunics /poly vinyl alchol) using N-methylmorpholine-N-oxide(NMMO)/water(87/13)(wt/wt) as a solvent by dry-wet spinning. The chemical cellulose (94%, ${\alpha}$-cellulose content) used for this study is extracted from styela clava tunics (SCT, Midduck), which are treated in chemical process and mechanical grinding. The structure and physical properties of regenerated composite fibers were investigated through IR-spetra, DSC, TGA and SEM. The optimal blend ratio of SCT/PVA for spinning solution was 70/30 and the total weight was 4% concentrations in NMMO/water solvent system. The fiber density, moisture contents and the degree of swelling were $1.5(g/cm^3)$ 10.2(%) and 365(%), respectively. The crystallinity index of composite fibers are decreased as the PVA contents increased. Thermal decomposition of composite fibers took place in two stages at around $250^{\circ}C$ and $550^{\circ}C$. The best thermal stability was obtained with 30% PVA contents.