• Journal of the Korean Wood Science and Technology
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• 제43권5호
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• pp.613-627
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• 2015

Simple methods of conductometric titration and infrared spectroscopy were used to quantify the surface carboxyl content of cellulose fibrils isolated by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The effects of different cellulose sources, post or assisted-sonication oxidation treatment, and the amount of sodium hypochlorite addition on the carboxyl content of cellulose were reported. This study showed that post sonication treatment had no influence on the improvement of surface carboxyl charge of cellulose macrofibrils (CMFs). However, the carboxyl content increased for the isolated cellulose nanofibrils (CNFs). Thus the carboxyl content of CNFs is different from those of their corresponding bulk oxidized cellulose and CMFs. Filter paper as a CNF source imparted a higher surface charge than did hardwood bleached kraft pulp (HWBKP) and microcrystalline cellulose (MCC). It was considered that the crystallinity and microstructure of the initial cellulose affected oxidation efficiency. In addition, the carboxyl content of cellulose was successfully controlled by applying sonication treatment during the oxidation reaction and adjusting the amount of sodium hypochlorite.

• Macromolecular Research
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• 제13권1호
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• pp.62-67
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• 2005

This paper investigated the effect of biodegradation behavior on the oxidation of cellulose nanofiber mats. The cellulose mats were produced through electro spinning. The diameter of an electrospun fiber varied from 90 to 240 nm depending on the electrospinning parameters, such as the solution concentration, needle diameter, and rotation speed of a grounded collector. Oxidized cellulose (OC).mats containing different carboxyl contents were prepared using $NO_2$ as an oxidant. The total carboxyl content of the cellulose nanofiber mats obtained after oxidation for 20 h was $20.6\%$. The corresponding carboxyl content was important from a commercial point of view because OC containing $16-24\%$ carboxyl content are used widely in the medical field as a form of powder or knitted fabric. Degradation tests of the OC mats were performed at $37^{\circ}C$ in phosphate-buffered saline (pH 7.4). Microscopy techniques were introduced to study the morphological properties and the degradation behavior of the OC mats. Morphological changes of the mats were visualized using optical microscopy. Within 4 days of exposure to PBS, the weight loss of the OC mats was $>90\%$.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.265-270
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• 2006

This paper reports an improved headspace gas chromatographic method for the determination of carboxyl group content in wood fibers. Pretreatment of wood fibers was applied using dilute HCl to convert carboxyl groups to carboxylic acid groups and then using deionized water to wash fiber samples thoroughly. The samples were finally air dried. Sodium bicarbonate solution was used to react with carboxylic acid groups of the pretreated fibers in a closed testing vial to release carbon dioxide. The content of carboxyl groups in fibers was accurately quantified by determining the amount of carbon dioxide released by a headspace gas chromatograph equipped with a thermal conductivity detector. The modified process for fiber sample pretreatment increased the reliability and accuracy in measuring carboxylic acid groups. The present method is simple, accurate.

• 한국환경과학회지
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• 제23권11호
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• pp.1821-1826
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• 2014

The adsorption characteristics of the methylene blue (MB) were studied using three activated carbons such as ACA and ACB with similar specific surface area (1,185 and $1,105m^2/g$), and ACC with relatively high specific surface area ($1,760m^2/g$). The surface chemical properties of these activated carbons were investigated by X-ray photoelectron spectroscopy (XPS). The results indicated that ACA had more functional groups (with phenol, carbonyl, and carboxyl etc.) than ACB (with carbonyl and carboxyl) and ACC (with carboxyl). The isotherm data were fitted well by Langmuir isotherm model. The adsorption capacities of ACA, ACB, and ACC for MB were 454.7 mg/g, 337.7 mg/g, and 414.0 mg/g, respectively. As phenol and carboxyl content of the surface on activated carbon increased, MB adsorption capacity was increased. Although ACA had a smaller specific surface area than ACC, the content of phenol and carboxyl group was abundant, so MB adsorption capacity was found to be higher than ACC.

• 접착 및 계면
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• 제2권1호
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• pp.18-22
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• 2001

Poly(vinylidene fluoride)(PVDF)를 포함하는 고분자 블렌드 필름의 표면층의 모폴로지를 원자력간 현미경과 시차주사열량계 측정을 토대로 연구하였다. ${\alpha}$ 및 ${\gamma}$형 결정상을 가진 PVDF는 Poly(methyl methacrylate)(PMMA) 및 가수분해된 PMMA(carboxyl content:14wt%)와의 블렌딩에서 표면층은 PVDF의 결정상만으로 이루어져 있음을 확인하였다. 그러나 PMMA의 결정상이 가수분해율이 증가함에 따라 표면 자유에너지의 차이도 증가함에도 불구하고 가수분해된 PMMA의 존재를 확인하였다. 이러한 결과는 표면층에서의 낮은 표면 자유에너지 성분인 PVDF의 농축 정도는 자유에너지 차보다 상호작용력의 크기에 밀접히 관련되어 있음을 알 수 있었다. 한편, carboxyl group의 도입은 PVDF와 PMMA의 상용성을 저해하는 것으로 밝혀졌다.

• 한국의류학회지
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• 제20권2호
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• pp.270-281
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• 1996

This study was carried to figure out the effect of bleaching on the cationic surfactant (DSDMAC) absorption by cotton fabrics. And physico-chemical change, static electricity, and fabric stiffness of bleached cotton fabrics were measured. Cotton fabrics bleached with sodium hypochlorite soluton and with sodium percarbonate solution were used to analyze the DADMAC absorption. The results were as follows: 1. As the number of bleaching cycles were increased, the degree of oxidation on cotton fabrics was increased. So their carboxyl content was increased and their tensile strength was decreased. 2. DSDMAC absorption by cotton fabrics was increased by bleaching and was in propor- tion to carboxyl content. Therefore, it was groved that DSDMAC absorption by cotton fabrics was motivated by ion exchange mechanism. 3. The static electricity of cotton fabrics almost no change when bleached and unbleached absorption had no effect on the static electricity of cotton fabrics. 4. DSDMAC which was absorbed by cotton fabrics acted as a lubricant. DSDMAC absorption reduced the friction coefficient of yarn, so stiffness of cotton fabric was decreased.

• Journal of the Korean Wood Science and Technology
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• 제48권2호
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• pp.231-244
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• 2020

As a way of finding value-added materials from waste medium density fiberboard (MDF), this study characterized cellulose nanocrystals (CNCs) isolated by ammonium persulfate (APS) oxidation using recycled MDF fibers. Chemical composition of the recycled MDF fibers was done to quantify α-cellulose, hemicellulose, lignin, nitrogen, ash and extractives. The APS oxidation was performed at 60 ℃ for 16 h, followed by ultrasonication, which resulted in a CNC yield of 11%. Transmission electron microscope images showed that rod-like CNCs had an average length and diameter of 167±47 nm and 8.24±2.28 nm, respectively, which gave an aspect ratio of about 20. The conductometric titration of aqueous CNCs suspension resulted in a carboxyl content of 0.24 mmol/g and the degree of oxidation was 0.04. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy clearly showed the presence of carboxyl group on the CNCs prepared by the APS oxidation. The change of pH of the aqueous CNC suspension from 4 to 7 converted the carboxyl group to sodium carboxylate group. These results showed that the APS oxidation was facile and CNCs had a one-step preparation method, and thus suggested an optimization of the oxidation condition in future.

• 공업화학
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• 제9권2호
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• pp.172-176
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• 1998

에폭시 adduct carboxyl terminated butadiene acrylonitrile(CTBN)은 CTBN과 에폭시수지를 블렌딩하여 제조하였다. CTBN과 폴리우레탄(PU) 및 에폭시수지로 CTBN/PU/epoxy를 제조하였다. CTBN이 5 wt%에서 CTBN/PU/Epoxy는 PU의 함량이 증가할 수록 damping 피크가 이동하였다. PU의 함량이 증가할수록 상용성이 증가함을 의미한다. 그러나 CTBN의 함량이 증가함에 따라 상용성은 감소하였다. CTBN/PU/epoxy에서는 PU의 함량이 10wt%에서 최대 굴곡값을 나타냈으나, PU 함량이 증가할수록 감소하였다. CTBN/epoxy에서 PU를 첨가함에 따라 파괴인성은 증가하였다. 파괴단면에서 전단변형과 공동화에 의한 응력백화현상을 보였다. CTBN의 공동화와 PU를 도입한 에폭시 매트릭스의 전단변형이 CTBN/PU/epoxy의 강인화기구이다.

• 반도체디스플레이기술학회지
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• 제15권1호
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• pp.12-16
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• 2016

Toluene-free pressure sensitive adhesives were synthesized by using butyl acrylate (BA), 2-hydroxy ethyl acrylate, methyl methacrylate, acrylic acid (AA) as monomers and ethyl acetate as a solvent. The polymerization recipes were designed by changing 1, 3, 5 part per hundreds monomer (phm) of AA content on the basis of 100 BA parts. Two crosslinking agents, ethyl glycol diglycidyl ether (EDGE) and isophorone diisocyanate (IPDI) were added to the synthesized polymers to increase adhesion due to crosslinking. In the measurement of properties, holding power, peel strength, and initial tackiness increased with AA content due to crosslinking between carboxyl group in AA and epoxy group in EDGE and isocyanate group in IPDI. In the comparison of two crosslinking agents, EDGE showed better in the three properties than IPDI by better reaction of epoxy group of EDGE to carboxyl group of AA.

• 한국식품과학회지
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• 제30권1호
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• pp.42-48
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• 1998

찰옥수수 전분을 차아염소산 나트륨$(0{\sim}60{\;}mg/s{\;}starch)$과 반응시켜 제조한 찰옥수수 산화전분의 이화학적 특성 및 유화 안정성에 미치는 영향에 대하여 연구하였다. 찰옥수수 산화전분의 일반성분 중 조지방질 및 조단백질 함량은 차아염소산 나트륨 처리량의 증가에 따라 감소하여 조단백질 함량과 백색도와 부의 상관관계$(R^2=0.9847)$를 나타내었고 조회분 함량은 증가하여 염소 함량과정의 상관관계$(R^2=0.9693)$를 나타내었다. 산화전분의 카르복시기 함량은 활성염소 첨가 농도에 비례하여 증가하였다. 호화액의 점도는 차아염소산 나트륨 처리량에 따라 현저히 감소하였고, 용해도와 팽윤력은 산화도가 높을 수록 증가하었으며, 광투과도는 치환도가 증가할 수록 낮은 온도에서 높은 투과도를 나타내어 화화개시온도가 약 $15^{\circ}C$낮아졌고, 호화액의 투명도 또한 개선되었다. 물결합능력은 치환도가 증가할 수록 생성된 카르복시기로 인하여 감소하였다. 찰옥수수 전분의 입자는 다각형과 원형의 혼합물로 크기는 $3.7{\sim}20\;{\mu}m$였으며, 차아염소산 나트륨 처리량이 증가할 수록 전분 표면이 거칠어졌다. 찰옥수수 산화전분과 옥배유를 균질화하여 저장하는 동안 유화액은 산화전분의 치환도가 높을 수록 전분의 농도가 증가할 수록 유화 안정성이 증가하였다.