• Macromolecular Research
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• 제12권2호
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• pp.213-218
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• 2004

We have performed dispersion polymerization of acrylamide in tert-butyl alcohol/water mixture-using hydroxypropyl cellulose and ammonium persulfate as the stabilizer and the initiator, respectively - to study the effects that the concentration of monomer, initiator, and stabilizer, the tert-butyl alcohol/water ratios as polymerization media, and the reaction temperature have on, among other things, the polymerization kinetics, particle sizes, and molecular weights. The polymerization rate increased upon increasing the concentration of the monomer, initiator, and stabilizer, the water content in the tert-butyl alcohol/water media, and the polymerization temperature. The average particle size of the lattices increased upon increasing the concentration of initiator, the polymerization temperature, and the water content in the tert-butyl alcohol/water media, but it decreased upon increasing the concentration of monomer and stabilizer. The viscosity-average molecular weight increased upon increasing the concentration of monomer and stabilizer and the water content in the tert-butyl alcohol/water media, but it decreased upon increasing both the concentration of initiator and the polymerization temperature.

• Macromolecular Research
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• 제13권5호
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• pp.391-396
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• 2005

The polymerization of methyl methacrylate (MMA) was carried out using CuBr/bidentate phosphorus ligand catalyst systems. MMA polymerization with CuBr/phosphine-phosphinidene (PP) exhibited high conversion ($\~80\%$) in 5 h at $90^{\circ}C$ along with a linear increase of ln($[M]_0/[M]$) versus time, indicating constant concentration of the propagating radicals during the polymerization. The molecular weight of the prepared PMMA tended to increase with conversion, suggesting the living polymerization characteristic of the system. On the other hand, a large difference between the measured and theoretical molecular weight and a broad molecular weight distribution were observed, implicating possible incomplete control over the polymerization. This may have been caused by the low deactivation rate constant ($\kappa_{deact}$) of the system. The low $\kappa_{deact}$, would result in irreversible generation of radicals instead of reversible activation/deactivation process of ATRP. Polymerizations performed at different ligand to CuBr ratios and different monomer to initiator ratios did not afford better control over the polymerization, suggesting that the controllability of CuBr/phosphorus ligand system for ATRP is inherently limited.

• 대한가정학회지
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• 제30권1호
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• pp.1-9
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• 1992

Graft polymerization mechanism and rate of polymerization of MMA and MMA/4-VP onto cellulose fiber using Ce(IV) salt as an initiatior were investigated. It was shown that the concentration of Ce(IV) salt affected on the graft yield, graft efficiency, total conversion and the rate of graft polymerization. The graft yield and total cenversion for MMA grafted polymer were significantly higher than those for MMA/4-VP grafted polymer with variation of CAN concentration. In this system the oxidative termination by Ce(IV) salt was considered particularly in higher concentration Ce(IV) ion. The change in the mode of termination reactions with variation of CAN concentration made possible the presence of an optimum Ce(IV) ion concentration for maximum graft yield.

• Bulletin of the Korean Chemical Society
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• 제27권1호
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• pp.71-76
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• 2006

Porous polymer monolithic columns were prepared by the direct free radical copolymerization of methacrylic acid and ethylene glycol dimethacrylate within the confines of a chromatographic column in the presence of toluene-dodecanol as a porogenic solvent. The separation characteristics of the monolithic columns were tested by a homologous series of xanthine derivatives, theophylline and caffeine. The effects of the polymerization mixture composition and polymerization condition, mobile phase composition, flow rate and temperature on the retention times and separation efficiencies were investigated. The results showed that the selection of correct porogenic solvents and appropriate polymerization conditions are crucial for the preparation of the monolithic stationary phases. The separation efficiency was only extremely weakly dependent on flow rate and temperatures. Hydrogen-bonding interaction played an important role in the retention and separation. Compared with conventional particle columns, the monolithic column exhibited good stability, ease of regeneration, high separation efficiency and fast analysis.

• 대한화학회지
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• 제27권1호
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• pp.66-72
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• 1983

TDI (Toluene Diisocyanate)/KOH 촉매작용에 의한 2-pyrrolidone의 음이온 중합에 있어서 TDI / KOH 몰비율, KOH의 농도, 온도 및 시간이 중합에 미치는 영향을 조사하였다. TDI / KOH 몰비율이 0.25일 때 중합속도가 가장 빠르고 전환율도 높았으며, 또 KOH의 농도가 5몰퍼센트일 때 가장 높은 전환율과 점도가 얻어졌다. 중합온도는 $30^{\circ}C$인 경우가 $50^{\circ}C$에 비해 전환율이 높았으며 점도도 높았다. 최소자승법으로 계산하여 구한 중합속도상수($k_p$)의 값은 $30^{\circ}C$일 때 $57.53 {\ell}/mole{\cdot}min$였고, $50^{\circ}C$일 때 $52.36{\ell}/mole{\cdot}min$였다.

• Nuclear Engineering and Technology
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• 제4권4호
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• pp.301-305
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• 1972

육송 미송 포플라 등 국산 연질 목재에 단량체 또는 단량체 혼합물을 촉매와 함께 침투시키고 열중합함에 있어서 시간에 따르는 중합율을 구하고 이것을 방사선 중합으로 WPC를 제조할 때 얻은 간과 비교 검토하여 다음과 같은 결론을 얻었다. (1) 중합율로 보아서는 육송, 미송이 포플라보다 좋으며 M.M.A.가 다른 단량체보다 효과적이다. (2) 비닐아세테이트는 일반적으로 열중합에 의한 중합율이 저조한 편이며 특히 포플라에 침투된 경우 매우 낮아 W.P.C.를 만들기 곤란하다. 그러나 비닐아세테이트와 M.M.A.를 같이 침투시키면 나무종류나 중합방법에 별 관계없이 매우 빨리 중합하여 가장 효과적이다. (3) 나무에 침투된 단량체나 단량체 혼합물의 중합의 경향은 나무가 많은량의 수지를 함유하지 않는다면 중합방법에 관계없이 단량체나 단량체 혼합물 자체만일때의 중합의 경향과 같다.

• 대한화학회지
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• 제22권6호
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• pp.423-430
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• 1978

트리옥산을 니트로벤젠 용매중에서 Ti$Cl_4$로서 중합시킬때 개시 반응기구를 연구하였다. 중합반응속도를 측정한결과 미량의 물이나 메탄올을 첨가하면 반응속도가 급격히 감소하였으며 중합을 개시하는 데는 조촉매로서 다른 물질이 필요 없음이 알려졌다. 유전상수 측정결과에 의하면 중합과정중 양성이온이 생기지 않으며 중합제나 개시제 용액의 전기전도도를 측정한 결과 개시 반응은 니트로벤젠 용매중에서 개시제가 동종간 주고 받기반응에 의하여 생긴 Ti$Cl_3^+$ 양이온에 의하여 일어난다는 것이 판명되었다.

• 공업화학
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• 제2권1호
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• pp.64-69
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• 1991

1, 2-Dithiolane 기를 갖는 lipid를 합성하여 vesicle 을 형성시킨 다음 이것을 ring opening polymerization 하여 고분자화된 vesicle을 합성하였다. 중합반응의 반응속도를 UV를 이용하여 측정한 결과, 반응속도가 1차반응 속도식을 만족하였으며 반응속도 상수값은 $3.84{\times}10^{-2}min^{-1}$이었다. 또한 sucrose를 이용한 투과도 실험에서 고분자화된 vesicle의 투과도는 $4.7{\times}10^{-8}cm\;hr^{-1}$이었으며 이 값은 고분자화되지 않은 경우보다 1.5배 낮은 것이다.

• Elastomers and Composites
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• 제28권4호
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• pp.267-273
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• 1993

A number of hydrophilic acrylic comonomers were incorporated into styrene-butadiene soap-free emulsion polymerization. It was found that reaction rate decreased according to : AN>AA>MMA>EA>IA>AAM>MA>HEMA. It was also observed that reaction rate increased with decreasing H-bonding factor contribution to the solubility parameter of the hydrophilic comonoer. The SBR latexes were very monodisperse with the particle size distribution of $1.03{\times}1.12$. Since growth rate is proportional to polymerization time, the difference in conversion rates between various comonomers was resulted from the particle number density of SBR latexes for the various hydrophilic comonomers. It was also found that the colloidal stability of the latexes was excellent because no external emulsifier was incorporated.

• 공업화학
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• 제17권1호
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• pp.33-36
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• 2006

광경화 접착제로 많이 사용되는 우레탄-아크릴레이트 올리고머의 광경화 거동을 자체촉매화 반응모델식을 통해 중합온도 및 올리고머의 관능성에 따른 영향을 확인하여 보았다. 중합온도가 증가함에 따라 최대중합속도는 감소하여 중합온도가 경화 거동에 대한 영향인자임을 확인할 수 있었으며, 반응속도상수 k는 온도증가에 따라 거의 일정한 값을 보이나 반응차수 m과 n은 증가하는 경향을 보였는데 이는 가교구조에 의한 반응성 기의 확산제한 및 유동성의 제한으로 인한 것으로 판단되어진다. 온도증가에 따른 중합속도의 감소는 주로 반응차수 n의 증가에 의해 진행되었다.