• 한국전기전자재료학회논문지
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• 제18권2호
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• pp.148-152
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• 2005

Atmospheric low-temperature plasma was produced using dielectric barrier discharge (DBD) plate-type plasma reactor and high frequency of 13.56 Hz. The surfaces of polyimide films for insulating and packaging materials were treated by the atmospheric low-temperature plasma. The contact angle of 67$^{\circ}$ was observed before the plasma treatment. The contact angle was decreased with deceasing the velocity of plasma treatment. In case of oxygen content of 0.2 %, electrode gap of 2 mm, the velocity of plasma treatment of 20 mm/sec, and input power of 400 W, the minimum contact angle of 13$^{\circ}$ was observed. The chemical characteristics of polyimide film after the plama treatment were investigated using X-ray photoelectron spectroscopy (XPS), and new carboxyl group bond was observed. The surfaces of polyimide films were changed into hydrophilic by the atmospheric low-temperature plasma. The polyimide films having hydrophilic surface will be very useful as a packaging and insulating materials in electronic devices.

• Journal of the Korean Wood Science and Technology
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• 제23권2호
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• pp.37-46
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• 1995

The substitution of carboxymethylated hydroxyl group in pulp revealed more hydrophilic than hydroxyl group. And then fibers were more flexible, swell more which leads to better conformation between fibers in turn this raise paper strength. In this paper, we tried to chemical modifyings of recycled fiber, OCCs(old corrugated containers). Many researchers have examined chemical modification of papermaking fiber by partial carboxymethylation(PCM) using a organic solvent processes. We made modified PCM processes adapted waters m replace of the organic solvent. Our testings for the optimum conditions on the new method, conditions as reaction time, temperature, liquor ratios were designed likely plant system. Freenesses(SR$^{\circ}$) were increased following on carboxyl content of the samples. Handsheets of untreated samples and partial carboxymethylated OCCs were made by optimum conditions on different concentrations of the reagent. As results, maximum 25% strength increasing effects were obtained by the new method.

• Elastomers and Composites
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• 제55권3호
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• pp.167-175
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• 2020

Various studies have been conducted to improve silica dispersion of silica filled tire tread compounds; among them, silica wet masterbatch (WMB) technology is known to be suitable for manufacturing silica filled compounds that have high silica content and high dispersibility. Till now, the WMB study is focused on the natural rubber (NR) or emulsion styrene-butadiene rubber (ESBR) that does not have a silica-affinity functional group, and a study of NR or ESBR having a silica-affinity functional group is still not well known. Unlike the dry masterbatch technology, the WMB technology can solve the problems associated with the high Mooney viscosity when applied to silica-friendly rubber. However, a coagulant suitable for each functional group has not yet been determined. Therefore, in this study, different coagulant applied silica WMB was prepared by applying calcium chloride, sulfuric acid, acetic acid, and propionic acid by using a carboxyl group functionalized reversible addition fragmentation chain transfer ESBR. The evaluation of the WMB compounds revealed that the calcium chloride added WMB compound showed excellent silica dispersion, abrasion resistance, and rolling resistance.

• 산업식품공학
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• 제14권2호
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• pp.118-126
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• 2010

The fibrous material fraction as a by-product from the commercial aloe vera gel processing was obtained and freeze dried. The physicochemical characteristics such as the proximate composition, crystalline/surface structures and several physical functionalities including the water holding capacity (WHC), swelling capacity (SW), oil holding capacity (OHC), emulsion/foam properties and viscosity properties of this powdered sample (100 mesh) were investigated and analyzed by comparison with commercial $\alpha$-cellulose as a reference sample. The total dietary fiber content of powdered sample was very high as much as 87.5%, and the insoluble dietary and soluble dietary fiber content ratios were 77.6 and 22.4%, respectively. The FT-IR spectrum of powdered sample showed a typical polysaccharide property and exhibited a x-ray diffraction pattern for cellulose III and IV like structure. SW (8.24${\pm}$0.15 mL/g), WHC(6.40${\pm}$0.19 g water/g solid) and OHC(10.32${\pm}$0.29 g oil/g solid) of freeze dried aloe cellulose were about 3.3, 1.4 and 2 times higher than those of commercial $\alpha$-cellulose, respectively. Aloe cellulose (~2%, w/v) alone had no foam capacity while improved the foam stability of protein solution (1% albumin+0.5% $CaCl_{2}$) by factor of 300%. Emulsion capacity of 2%(w/v) aloe cellulose was about 70% level of 0.5%(w/v) xanthan gum, but its emulsion stability was about 1.2 times higher than that of xanthan gum. Also, aloe cellulose containing CMC (carboxyl methyl cellulose) of 0.3%(w/v) showed a very good dispersity. Aloe cellulose dispersion of above 1%(w/v) exhibited higher pseudoplasticity and concentration dependence than those of $\alpha$-cellulose dispersion, indicating the viscosity properties for new potential usage such as an excellent thickening agent.

• Journal of the Korean Wood Science and Technology
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• 제45권4호
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• pp.432-443
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• 2017

Maltodextrin and citric acid are two types of natural materials with the potential as an eco-friendly binder. Maltodextrin is a natural substance rich in hydroxyl groups and can form hydrogen bonds with lignoselulosic material, while citric acid is a polycarboxylic acid which can form an ester bond with a hydroxyl group at lignoselulosic material. The combination of maltodextrin and citric acid as a natural binder materials supposed to be increase the ester bonds formed within the particleboard. This research determined to investigate the bonding properties of a new adhesive composed of maltodextrin/citric acid for nipa frond particleboard. Maltodextrin and citric acid were dissolved in distillated water at the ratios of 100/0, 87.5/12.5, 75/25 and 0/100, and the concentration of the solution was adjusted to 50% for maltodextrin and 60% citric acid (wt%). This adhesive solution was sprayed onto the particles at 20% resin content based on the weight of oven dried particles. Particleboards with a size of $25{\times}25{\times}1cm$, a target density $800kg/m^3$ were prepared by hot-pressing at press temperatures of $180^{\circ}C$ or $200^{\circ}C$, a press time of 10 minute and board pressure 3.6 MPa. Physical and mechanical properties of particleboard were tested by a standard method (JIS A 5908). The results showed that added citric acid level in maltodextrin/citric acid composition and hot-pressing temperature had affected to the properties of particleboard. The optimum properties of the board were achieved at a pressing temperature of $180^{\circ}C$ and the addition of only 20% citric acid. The results also indicated that the peak intensity of C=O group increased and OH group decreased with the addition of citric acid and an increase in the pressing temperature, suggesting an interreaction between the hydroxyl groups from the lignocellulosic materials and carboxyl groups from citric acid to form the ester groups.

• Macromolecular Research
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• 제17권9호
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• pp.709-713
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• 2009

The aim of this study was to develop novel intestinal specific drug delivery systems with pH sensitive swelling and drug release properties. The carboxyl group of ibuprofen was converted to a vinyl ester group by reacting ibuprofen and vinyl acetate as an acylating agent in the presence of catalyst. The glucose-6-acrylate-1, 2, 3, 4-tetraacetate (GATA) monomer was prepared under mild conditions. Cubane-1, 4-dicarboxylic acid (CDA) linked to two 2-hydroxyethyl methacrylate (HEMA) group was used as the crosslinking agent (CA). Methacrylic-type polymeric prodrugs were synthesized by the free radical copolymerization of methacrylic acid, vinyl ester derivative of ibuprofen (VIP) and GATA in the presence of cubane cross linking agent. The structure of VIP was characterized and confirmed by FTIR, $^1H$ NMR and $^{13}C$ NMR spectroscopy. The composition of the cross-linked three-dimensional polymers was determined by FTIR spectroscopy. The hydrolysis of drug polymer conjugates was carried out in cel-lophane membrane dialysis bags, and the in vitro release profiles were established separately in enzyme-free simulated gastric and intestinal fluids (SGF, pH 1 and SIF, pH 7.4). The detection of a hydrolysis solution by UV spectroscopy at selected intervals showed that the drug can be released by hydrolysis of the ester bond between the drug and polymer backbone at a low rate. Drug release studies showed that increasing the MAA content in the copolymer enhances the rate of hydrolysis in SIP. These results suggest that these polymeric prodrugs can be useful for the release of ibuprofen in controlled release systems.

• 한국염색가공학회지
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• 제8권3호
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• pp.8-15
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• 1996

Three pieces of cotton fabrics used for this study were exhumed in the Mt.Moo Deung near Kwang Ju in 1965. The fabrics were remains of Jang Heung Lim Si-the nephew's wife of General Kim Deok Ryeong. It was reported that Jang Heung Lim Si died in 1615. The cotton fabrics were classified into three, A, B and C, according to their color. The fabric A was inherent color of cotton, the fabric B was that of light brown and the fabric C was that of dark brown. The physical and chemical characteristics of the cotton fabrics were examined. In the meantime the construction of cotton fabrics and traditional dyeing of Yi dynasty were studied through various records. The results were as follows: 1. According to electromicroscopic examination, the lumen in the cotton fiber had not been developed enough, therefore the quality of cotton at that time was supposed to be not so excellent. 2. The results of chemical analysis indicated that: (1) While the copper number of the cotton fabric A was similar to that of bleached cotton, that of the fabric C was extremely high. (2) The amount of methylene blue absorption was much more than that of normal cotton. (3) The content of cellulose was less than that of normal cotton. (4) The degree of polymerization was less than that of normal cotton. From the results mentioned above, it was concluded that the cotton fabrics were oxidized slowly in the closed lime coffin for a long period of time. From this process of oxidization and deterioration, the degree of polymerization was decreased through depolymerization, and carboxyl groups were produced by the oxidization at reducing end groups. 3. It was confirmed that the cotton fabric C was dyed by the juice of immature persimmon. Thus, it was inferred that the large amount of copper number of cotton fabric C was derived from phenolic OH groups of tannins having high reducing properties in persimmon.

• 공업화학
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• 제23권5호
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• pp.462-466
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• 2012

베타-사이클로덱스트린($\beta$-cyclodextrin, $\beta$-CD) 중합체(polymer)는 가교제인 epichlorohydrin (EPI)과 $\beta$-CD의 몰 비가 10 : 1으로, 강한 염기조건에서 합성하였다. 합성한 $\beta$-CD 중합체 내의 $\beta$-CD contents는 52%였다. 광, pH반응성 복합체를 제조하기 위해 신남산을 첨가하였고 첨가된 신남산은 소수성 상호작용에 의해 $\beta$-CD 공동에 포접되었다. 형성된 $\beta$-CD 중합체와 신남산 복합체를 투과전자현미경을 이용하여 관찰하였을 때 복합체의 형상을 관찰하였다. 광 조사에 따른 이량화도는 $\lambda$ = 365 nm의 UV조사 시 증가하였으며 $\lambda$ = 254 nm의 UV조사 시 감소하였다. 또한 동적 광 산란(dynamic light scattering)장치를 이용하여 측정한 복합체의 크기는 광 조사 유무에 따라 큰 변화가 측정 되지 않았고, pH 반응성을 관찰한 실험에서도 복합체의 크기와 제타 전위(zeta potential) 모두 pH에 따른 변화가 나타나지 않았다.

• Composites Research
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• 제36권5호
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• pp.355-360
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• 2023

에폭시계 탄소섬유복합재는 고유의 높은 취성특성으로 인해 산업 응용에 적합성에 한계로 인성 특성을 향상시키기 위한 광범위한 연구가 진행되고 있다. 본 연구는 최소 함량을 활용하는 데 중점을 두고 PA6입자(pPA6)와 CTBN에 의한 인성 메커니즘을 평가하는 데 초점을 맞춰 Mode I 파단 인성 및 인장강도 분석을 통해 다양한 농도의 p-PA6와 CTBN 첨가제, 즉 0.5, 1, 2.5 및 5 phr의 영향을 평가하였다. p-PA6는 1 phr의 비교적 낮은 비율에서 인성이 강화되었으며, 인장강도를 유지하면서 동시에 향상된 인성에 기여하는 지속적인 파단 거동으로 나타났다. 또한, p-PA6의 입자 응집에 영향에 의해 전체적인 인성 메커니즘에 영향을 미치는 것을 확인하였다. CTBN 첨가는 2.5 phr 이상의 높은 농도에서 인성의 증가하나, 인장강도의 감소를 동반하고 취성을 나타내는 기존의 복합재와 유사한 파단 거동을 관찰하였으며, p-PA6, CTBN 두 첨가 기술은 특정 농도 조건에서 인장강도를 미세하게 향상시키는 것으로 확인하였다. 해당 결과를 통해 p-PA6, CTBN 강화 기술 적용에 최적화된 조건이 확립하였다.

• 분석과학
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• 제16권4호
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• pp.283-291
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• 2003

본 연구에서는 깊이별 토양시료에서 추출한 휴믹산과 풀빅산의 산성 작용기 및 구조 적 특성을 비교 분석하였다. 연구의 주요 목적은 토양 깊이별 방사성 핵종 농도 분포 및 이동성에 대한 휴믹물질의 역활 규명에 필요한 기초자료를 제공함에 있다. 휴믹산과 풀빅산 분자의 산성작용기 특성은 pH 적정법을 이용하여 분석하였고, 양성자교환용량 (PEC) 및 평균 $pK_a$ 값을 얻었다. 휴믹산과 풀빅산의 구조적 특성은 원소성분비 분석 및 CPMAS $^{13}C$ NMR 분광법을 이용하여 분석하였다. pH 적정 분석 결과, 휴믹산의 PEC 값은 $3.8{\sim}4.8meq\;g^{-1}$의 범위이었다. 풀빅산은 휴믹산에 비하여 상대적으로 높은 $5.5{\sim}7.0meq\;g^{-1}$의 PEC 값을 보였다. 깊이별 토양 휴믹산은 표층에서 보다 하층 (> 8 cm)에서 더 높은 PEC 값을 나타냈다. 원소성분비 (H/C) 및 $^{13}C$ NMR 스펙트럼 분석 ($C_{arom}/C_{aliph}$) 결과, 휴믹산이 풀빅산에 비하여 구조적으로 방향족성이 높고, 카르복실기 탄소 함량은 낮은 것으로 나타났다. 깊이별 비교의 경우, 휴믹산은 토양 깊이가 증가할수록 방향족성 및 카르복실 탄소 함량이 증가하는 경향을 보였으나, 풀빅산은 전체적으로 유사한 함량 분포를 보였다.