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신혜경,정용식,박병기,이효진,김의화,Shin, Hye-Kyoung,Chung, Yong-Sik,Park, Pyong-Ki,Lee, Hyo-Jin,Kim, Eui-Hwa 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.6
Chitosan is the second abundant natural polymer after cellulose and shows a lot of potential functional advantages such as biodegradability, biocompatibility, antimicrobial properties etc. Cotton knit/chitosan sponge composite structures were prepared by coating chitosan solutions ($CH_3COOH$, HCI) onto the cotton knit fabrics, freezing at $-80^{\circ}C$, and Iyophilizing. Chitosan in two kinds of salts solutions was crosslinked with glutaraldehyde and citric acid prior to coating. Knit/chitosan sponge structures were transformed into the hydrogel structure when they absorbed water. 2% chitosan acetate composite crosslinked with citric acid absorbed water about 23 times of its dry weight. Weak physical properties of Iyophilized chitosan sponge were improved by forming knit/chitosan composite structure.
그래핀 산화물/알지네이트 기반 그라파이트 섬유의 제조 및 특성
임나영,심진태,정용식,Lim, Na-Young,Shim, Jin-Tae,Chung, Yong-Sik 한국섬유공학회 2018 한국섬유공학회지 Vol.55 No.6
Graphene oxide can be prepared from graphene by introducing hydrophilic functional groups to facilitate dispersion in water. This process has attracted significant attention for production of fillers for polymer composite materials. Alginate is a natural polymer that can be used as a composite fiber matrix that is industrially applicable and is currently being studied for the development of novel materials. Graphene oxide/alginate composite fibers were prepared with various graphene oxide contents by wet spinning in a calcium chloride coagulation solution. To improve thermal and electrical properties, the graphene oxide/alginate fibers were reduced using hydrogen iodide and acetic acid. After low temperature carbonization over a graphite nickel catalyst, the yield of the carbonized alginate precursor increased from 20.3% to 36.1% upon addition of graphene oxide. After reduction and carbonization, XRD analysis showed the presence of a $2{\theta}=26.4^{\circ}$ peak arising from the (002) plane of the graphite structure. In addition, electrical conductivity increased from 225 to 13575 S/m, indicating that the composite fibers successfully incorporated graphite.
에탄올 비용매를 이용한 메타아라미드 피브리드 제조 및 형태학적 특성
백병운,김완진,정용식,Baek, Byungwoon,Kim, Wan Jin,Chung, Yong Sik 한국섬유공학회 2014 한국섬유공학회지 Vol.51 No.3
Fibrids are materials of a complex fibrous, film-like, or intermediate form. The diameter of the particles varies between $20-50{\mu}m$, and $100-10,000{\mu}m$. The optimal form and size of the particles depends in each case on the area of application. The fibrid form is the result of two processes, viz. a wave process and diffusion. The life span and break-up pattern of the polymer depend on the interphase surface tension, the viscosity of the polymer, and the diffusion speed ratio of the polymer and medium. In this study, m-aramid was polymerized at low temperature and in solution with an equal molar ratio of MPD and IPC in DMAc. The meta-aramid solution was prepared by dissolution in DMAc, and ethanol was used as a coagulation bath. The rotation speed was the main factor affecting the formation and morphology of the fibrid. Meta-aramid paper was produced from m-aramid fiber with meta-aramid fibrid by wet laying. The results showed that fibrid particle sizes decreased with increasing rotation speeds and decreasing concentrations of m-aramid in the solution. The properties of the m-aramid fibrid as a function of the processing conditions were investigated using an image analyzer, optical microscopy, and SEM. The resulting meta-aramid paper was analyzed in terms of its morphology, thickness, air permeability, and mechanical properties.
신혜경,민지호,정용식,Shin, Hye-Kyung,Min, Ji-Ho,Chung, Yong-Sik 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.2
Antimicrobial acitivity of chitosan fiber was reinforced by N-halamine which is a compound containing nitrogen-chlorine covalent bond that is formed by halogenation of amine in chitosan. Upon pH and chlorination time of sodium hypochlorite solution, aminogroup in chitosan fiber was differnetly chlorinated according to respective conditions. The chlorination of chitosan fiber was confirmed by iodometric titration. The results obtained are following: longer reaction time caused the chlorination of chitosan fibers to increase, and acidic conditions during the treatemnt was more effective compared to alkaline or neutral conditions. The chlorinated chitosan fibers showed powerful antimicrobial activity against both E. coli and S. aureus. SEM observations demonstrated that the chlorinated chitosan fibers were not damaged under the acidic treatment condition.
메타아라미드/Poly(vinyl alcohol)에 복합섬유의 제조 및 특성 분석
전언,정민호,정용식,김환철,Jun, Eon,Jeong, Min-Ho,Chung, Yong-Sik,Kim, Hwan-Chul 한국섬유공학회 2011 한국섬유공학회지 Vol.48 No.1
Poly(vinyl alcohol)(PVA) was dissolved in DMSO(dimethyl sulfoxide) and m-aramid was dissolved in DMAc(dimethyl acetamide). The composite fibers were prepared by wet-spinning a mixture of the m-aramid and PYA solutions with methyl alcohol as a coagulant. The ratio of m-aramid to PYA was 10/90, 20/80, 30/70, 40/60, 50/50 wt%. The composite fibers had sea-island bicomponent structures; the island component was m-aramid and the sea component was PYA. The nano-sized m-aramid fibers were obtained by washing out PYA with boiling water. Phase separation in theses immiscible polymer solution blends led to m-aramid being extracted in a nano-sized fiber state. The diameter of the fibrillated m-aramid fibers decreased as the PYA contents increased (130~313 nm). This study provided a new method to make nano-sized m-aramid fibers with wet-spinning.
박제기,김동환,정용식,김환철,Park, Jac-Ky,Kim, Dong-Hwan,Chung, Yong-Sik,Kim, Hwan-Chul 한국섬유공학회 2009 한국섬유공학회지 Vol.46 No.4
PVA/collagen blend fibers were produced by air-gap spinning method, and were successfully spun to blend fiber. Maximum collagen content to produce the fiber was 30%, above which the fiber was found to be broken in the drawing process. Thermal and mechanical properties of the fibers were investigated by changing blend ratios of the PVA to collagen. Melting point of PVA was decreased with the increase of the amount of collagen. The strength and the elongation of the fiber were also decreased due to the inhomogeneous structure of the blend fiber. Hot water resistance was endowed by the heat treatment after drawing process, and when the fiber was treated at $230^{\circ}C$ for 10 minutes, it was neither swelled nor broken in boiling water.
박병기,한태희,정용식,Park Pyong-Ki,Han Tae-Hui,Chung Yong-Sik 한국섬유공학회 2006 한국섬유공학회지 Vol.43 No.2
The Hanji treated with citric acid as crosslinking agent was prepared to improve wet dimensional stability and wet-strength. To improve dyeability for direct and reactive dyes, various concentrations of chitosan were added in crosslinking process. The wet dimensional stability and wet-strength of crosslinked Hanji were improved by citric acid addition, whereas the folding endurance significantly decreased. As the concentration of citric acid increased, K/S values of the crosslinked Hanji for berberin increased, but those direct and reactive dyes decreased. However, the dye adsorption for direct dye and reactive dye were improved by chitosan addition.