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        검색결과 13

        1.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 3차원 네트워크 폴리아크릴산나트륨 겔의 가교환경을 변화시켜 기계적 강도 및 팽윤거동을 제어하고 그 물성을 평가하는 연구를 진행하였다. 일반적으로 겔 용액의 가교도가 증가함에 따라 3차원 네트워크 겔의 팽윤비는 감소하고 겔의 기계적 강도는 증가한다. 본 연구에서는 3차원 네트워크 겔 상의 가교개수밀도를 산출하여, 겔화 과정에서 가교환경에 의존하는 중합효율 및 가교효율을 확인하였다. 그 결과, 겔 용액에서 단량체와 가교제의 중량비가 동일하더라도 가교환경이 달라지면 실제 제조된 겔 내부의 가교개수밀도가 3.6배 이상 달라질 수 있음을 확인하였다. 본 연구에서 시도한 가교개수밀도 기반 겔 평가 방법을 활용하면 효과적인 VOCs 흡수제로써 3차원 네트워크 겔을 최적화 할 수 있으리라 기대된다.
        4,000원
        2.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        가공식품에서 폴리아크릴산나트륨에 대한 분석 방법을 size-exclusion chromatography를 사용하여 개발하고 유통중인 가공식품에 대해 모니터링 하였다. 분석조건에 대하여 GF-7M HQ column과 UV / VIS 검출기를 피크 모양과 선형성을 기준으로 선택하였으며, 유속, column oven 온도 및 이동상은 각각 0.6 mL/min, 45℃ 및 50 mM sodium phosphate buffer (pH 9.0)으로 선정되었다. 시료의 전처리를 위하여 pH 7.0의 50 mM sodium phosphate buffer로 20℃, 150 rpm에서 3 시간 동안 추출하였다. 확립된 분석법을 검증한 결과 적절한 선택성을 나타내었으며, 검량선은 50~500 mg/L의 범위에서 선정되었고, 이때 검량선의 상관계수(R2)는 0.9985로 나타났다. 폴리아크릴산나트륨의 검출한계(LOD)는 10.95 mg/kg으로 정량한계(LOQ)는 33.19mg/kg의 값을 얻었으며, 정밀도는 intra-day의 경우 3.0~8.3%를, inter day의 경우 1.3~2.6%로 확인되었다. 정확도는 intra-day의 경우 99.6~127.6%를 나타내었으며, interday의 경우 94.3~121.9%로 확인되었다. 유통 중인 가공식품 125품목을 대상으로 폴리아크릴산나트륨의 함유량을 분석한 결과 40품목에서 검출되었으며, 검출량은 식품첨가물공전의 규격인 0.2% 미만으로 검출되었다. 본 연구 결과는 size-exclusion chromatography에 의한 분석방법이 가공식품에서 폴리아크릴산나트륨을 분석하는데 적용할 수 있는 적합한 방법이라는 것을 나타내었다.
        4,000원
        3.
        2017.10 구독 인증기관·개인회원 무료
        콘크리트 포장의 내구성 저하는 포장체의 파손뿐만 아니라 사용자의 주행성에도 영향을 주며, 또한 유지관리 비용을 증가시키는 등 복합적 문제를 초래한다. 이러한 콘크리트 내구성 문제를 개선하기 위한 방안으로 콘크리트의 내부양생(internal curing)에 대한 관심이 고조되고 있다. 내부양생은 표면 살수나 피막양생제를 도포하는 기존의 양생 방식과는 달리 콘크리트 배합 시 수분공급 물질을 혼입하여 내부로부터 수분을 공급하는 기법으로, 양생효율을 현저히 증진시켜 역학적 특성, 투수 및 균열 저항성, 부피안정성 등 콘크리트의 다양한 성능을 향상시키는 것으로 잘 알려져 있다. 특히 포장용 콘크리트 배합과 같이 광물성혼화재(SCMs)를 포함하는 경우, 소요성능의 발현을 위해서는 철저한 양생이 무엇보다 중요하다. 이에 착안하여 본 연구에서는 최근 콘크리트의 내부양생 재료로서 각광을 받고 있는 고흡수성폴리머(SAP)를 적용한 모르타르의 강도 및 부피변화 특성을 파악하여 콘크리트 포장에의 적용 가능성을 평가하였다. 이를 위하여 가교밀도와 평균 입자크기가 다른 4종의 폴라아크릴산나트륨 SAP를 혼입한 모르타르를 제작하고 SAP 함량 및 종류별 강도 발현, 자기수축 및 내부 상대습도 거동 특성을 측정하였다.
        4.
        2001.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Antibiotics polymer prepared by chemical bonding and simple blending of antibacterial into polymers have attracted much interest because of their long-lasting and antibacterial activity. Antibiotics polymer can significantly reduce losses associated with dissolution, photolytic decomposition and volatillization. Further more, increased efficiency safety and selectivity are additional benefits which may be realized. In this study, Antibiotics polymer was synthesized by chemical reaction of polyacrylic acid with sulfamethazine by N,N'-dicyclohexylcarbodiimide(DCC) method. Antibacterial susceptibility was determined against Streptococcus pyrogenes[gram(+)] and Esherichia coli.[gram(-)] using a standardized disc test. As a result, the synthetic antibiotics polymer exhibited the broad susceptibilty against Streptococcus pyrogenes and Esherichia coli. Especially, the antibiotic effect of antibacterial polymer against Gram negative(Esherichia coli) was much stronger than that against Gram positive(Streptococcus pyrogenes).
        4,000원
        7.
        1993.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Ground Calcium Carbonate, among paper coating pigments, will influence less dispersant demand, less binder demand, increase coating solids from 58% to 70%, which means high speed coating, less shrinkage during drying, less energy consumption, more uniform coverage of fibers. The quality point of view of Ground Calcium Carbonate, brightness, particle size, Particle size distribution, hardness, impurities content are important. More important factors of Ground Calcium Carbonate which influence the paper coating process are dispersion mechanisms and their effects. The study was made to investigate the effect of Ground Calcium Carbonate dispersion by sodium salt of polyacrylate dispersant composition and dispersion condition. Basic tests such as physical, optical and chemical were perfumed, and dispersion effects were investigated by different conditions. The results showed that the type of dispersant affected the dispersion effects, and the Ground Calcium Carbonate has critical dispersant demand.
        4,000원
        8.
        1989.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        To developed new process for obtaining maximum molecular weight of anionic acrylamide and acrylic acid copolymer by inverse emulsion polymerization. Concentration of initiator, reducing agent, surfactant and mole ratio of acrylamide-acrylic acid were studied for the process. Semi-batch processes with method of redox, control of reaction temperature, feeding method of monomer and reaction time, was suitable for maximum molecular weight of P(AMAC) from this process obtained 3.09 × 106(Mn.) and 4.41 × 106(Mw.) in molecular weight measured by the intrinsic viscosity method. inverse emulsion polymerization mechanism of P(AMAC) does not followed the Smith-Ewart and Medvedev theory, but selected for concentration of initiator, reducing agent, surfactant, water solubility of monomer.
        4,000원
        9.
        2014.08 KCI 등재 서비스 종료(열람 제한)
        Electron beam-induced grafting polymerization was employed to prepare Acrylic acid-grafted bacterial cellulose (BC-g-AAc). BC-g-AAc as an adsorbent was applied to remove heavy metals (e.g., As, Pb, and Cd). This study examined followings; morphological change of surface, adsorptive behavior of BC-g-AAc, and interpretation of adsorptive kinetics. Specific surface areas of BC and BC-g-AAc were 0.9527 m2 g-1 for BC and 0.2272 m2 g-1 for BC-g-AAc, respectively as measured by BET nitrogen adsorption, revealing the morphological change of the surface of BC-g-AAc. Batch adsorption test was performed to investigate adsorptive behavior of BC-g-AAc in aqueous solution. The amounts of Pb and Cd adsorbed on BC-g-AAc were 69 mg g-1 and 56 mg g-1, respectively. However, As was not adsorbed on BC-g-AAc due to its neutral nature. Both the Benaissa model and the Kurniawan model were applied in the study to interpret adsorptive kinetics. From the value of correction coefficient (R2), adsorptive kinetics of Pb and Cd were subjected to Kurniawan model referred to pseudo-second-order. Taken together, the results of this study show that BC-g-AAc has potential as a heavy metal (eg., Pb, Cd)-adsorbent made of an environmentally friendly material.
        10.
        2014.07 KCI 등재 서비스 종료(열람 제한)
        This research investigated the feasibility of rice husk as a biosorbent for removal of ammonium ion from aqueous solutions. To improve the sorption functionality of rice husk, the carboxyl groups were chemically bound to the surface of the rice husk by graft polymerization of acrylic acid using potassium peroxydisulphate as a redox initiator. The removal of ammonium ion by rice husk grafted with acrylic acid (RH-g-AA) was studied in a batch mode and fixed bed columns. The kinetic and equilibrium data obtained from batch experiments follow the second-order kinetics and fit well with the Langmuir isotherm model. The sorption energy determined from D-R model was 8.61 kJ/mol indicating an ion-exchange process as the primary sorption mechanism. To determine the characteristic parameters of the column useful for process design, four mathematical models; Bed Depth Service Time (BDST), Bohart-Adams, Clark and Wolborska models were applied to experimental data obtained from the fixed bed columns with varying bed heights. All models were found to be suitable for simulating the whole or a definite part of breakthrough curves, but the Wolborska model was the best. The fixed bed sorption capacity determined from the Wolborska model was in the range 33.3 ~ 40.5 mg/g close to the value determined in the batch process. The thickness of mass-transfer zone was calculated to be approximately 40 mm from DBST model. The RH-g-AA sorbent could be regenerated by a simple acid washing process without a serious lowering the sorption capacity or physical durability.
        11.
        2013.06 KCI 등재 서비스 종료(열람 제한)
        This research investigated the feasibility of rice husk as a biosorbent for the removal of heavy metals from aqueous solutions. The carboxyl groups were chemically bound to the surface of the rice husk by graft polymerization of acrylic acid using potassium peroxydisulphate as a redox initiator. The Pb sorption capacity and FT-IR spectra confirmed the presence of carboxyl groups on the structural units of the acrylic acid-grafted rice husk (RH-g-AA). The sorption selectivity of the RH-g-AA for cations under competition with each other was high in the following order: Pb > Cu > Cd ≥ Fe > Mn > Zn > Ni > Mg > K > Cr > Ca. Sorption equilibrium of Pb on RH-g-AA was better described by the Fruendlich isotherm model than the Langmuir isotherm model. The sorption energy obtained from D-R model was 13.13 kJ/mol indicating an ion-exchange process as the primary sorption mechanism. Sorption kinetic data fitted with the pseudosecond- order kinetic model and indicated that both external and intraparticle diffusion took part in sorption processes. The RH-g-AA sorbent could be regenerated for more than 5 times by the washing process with 0.1 M HCl without a serious lowering the sorption capacity.