• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.889-894
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• 1999

Preparation of micron size polymer particles which have desired morphology, size, and structure by emulsion polymerization is very difficult due to coagulation of latex particles and formation of second generation particles. But there are attractive merits such as preparation of structural and functional polymer particles in seeded emulsion polymerization. Seeded emulsion polymerization of n-butyl acrylate(BA) was carried out to investigate the effects of stirring rate, reaction temperature, concentration of initiator, emulsifier, and cross-linking agent on the particle size and size distribution. By the combination of suitable reaction conditions, we succeeded in preparing $0.14{\sim}3.67{\mu}m$ diameter of poly(n-butyl acrylate)(PBA) particles using sequential seeded emulsion polymerization.

• Journal of the Korean Chemical Society
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• v.20 no.6
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• pp.525-532
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• 1976

Anionic polymerization of 2-pyrrolidone and ${\varepsilon}$-Caprolactam via $CO_2/KOH catalysis was attempted in order to find reaction condition and physical properties of polymers. In case of polymerization of 2-pyrrolidone, the yield of conversion was increased when the concentration of potassium hydroxide was reached above 8 mole percent. The optimum of CO_2/KOH$ mole ratio was 0.45. It was also found that the polymerization was taking place at moderate temperature which was around $50^{\circ}C$. With regard to polymerization of-caprolactam, the yield of conversion was relatively low at $80^{\circ}C$ to $90^{\circ}C$and higher yield of conversion was obtained at higher temperature between $150^{\circ}C$ to $180^{\circ}C$ regardless of $CO_2/KOH mole ratio. The inherent viscosity of nylon 4 and nylon 6 which was made via CO_2/KOH$ catalysis was measured. The observed inherent viscosity was between 2.0 to 5.0.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.771-776
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• 2016

The acrylate copolymer having good thermal stability, coating and adhesion properties was designed and prepared. We prepared copolymers in >95% high yield using methyl methacrylate, isobornyl methacrylate and 2-hydroxyethyl methacrylate monomers by the bulk and emulsion polymerization techniques. The $^1H$-NMR spectrum was used to identify chemical structure and glass transition temperatures increased from $123^{\circ}C$ to $140^{\circ}C$ confirmed by DSC, DMA and TGA analysis. In addition, as the content of IBMA increased, storage modulus and thermal decomposition temperature increased. As the content of IBMA increased from 10% to 30% in the composition for the entire monomer, tensile strength increased from 22 to 30 MPa in both polymers prepared by bulk and emulsion techniques. The contact angle increased from 70 to up to 88 degrees due to hydrophobic property of IBMA.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.397-400
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• 2015

The effects of surface treatment method of unreacted N-[3-(trimethoxysilyl)propyl]ethylenediamine (2NS), $N^1$-(3-trimethoxysilylpropyl)diethylenetriamine (3NS), and 3-cyanopropyltriethoxysilane (1NCy) after grafting on the surface of silica and of the surface treatment temperature on ethylene polymerization were investigated. The Zr content of supported catalyst employing filtering method was higher than that of washing method, and the activities of supported catalysts prepared by washing method were higher than those of filtering methods significantly. Regardless of surface treatment methods the activities were in order by $SiO_2/2NS/(n-BuCp)_2ZrCl_2>SiO_2/1NCy/(n-BuCp)_2ZrCl_2>SiO_2/3NS/(n-BuCp)_2ZrCl_2$. The ethylene polymerization activity was increased as the surface treatment temperature of aminosilane on silica increased.

• Elastomers and Composites
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• v.34 no.1
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• pp.3-10
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• 1999

Kinetics of solution photopolymerization of acrylonitrile(AN) with sensitizer, such as $NaSCN,\;KSCN,\;Ba(SCN)_2,\;NH_4SCN,\;ZnCl_2$ and $Na_2SeO_3$, were studied using UV crosslinker at various monomer concentrations($1.8{\sim}7.58mo1/1$), sensitizer concentrations($10{\sim}60%$), reaction temperature($10{\sim}70^{\circ}C$), energy intensities($1,000{\sim}9,900{\mu}J/cm^2$) at isothermal condition under nitrogen atmosphere. Under the irradiation of high pressure mercury lamp(${\lambda}=365nm$). High conversion and uniform molecular weight were obtained compare to thermal polymerization at reaction temperature of $50^{\circ}C$, reaction time of 3hr and 50% NaSCN without any initiator. Their kinetic model was as follows : $R_p=0.0142[M]^{0.82}[I]^{0.49}[S]^{0.52}$ exp(-1.33/RT).

• Polymer(Korea)
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• v.36 no.1
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• pp.65-70
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• 2012

Glycidyl methacrylate (GMA) was used to introduce epoxy groups on the surface of polypropylene (PP) plate, used as a substrate, through plasma-induced graft copolymerization. Emulsion polymerization was applied for graft copolymerization of GMA and was compared with conventional solution polymerization to confirm its effect. Plasma treatment conditions under one atmospheric pressure were fixed as follows; the RF power of 200 W, the treatment time of 30 sec, the Ar gas flow rate of 6 LPM, and the exposure time of treated PP samples in air of 5 min. For graft-copolymerization, GMA concentration, reaction temperature, and reaction time was optimized to maximize the grafting degree of GMA. The maximum grafting degree of GMA was obtained at the condition of 12%-GMA concentration, $90^{\circ}C$ reaction temperature, and 5 hr-reaction time. Analysis results supported that the emulsion polymerization was more effective than the solution polymerization for grafting more GMAs on the surface of PP plate under the same reaction conditions.

• The Journal of the Korean dental association
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• v.24 no.3 s.202
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• pp.199-203
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• 1986

치과용 인상재는 구강내에서 치아나 주위조직을 정확히 인기하여야 하며 조작이 간편하고 유동성이 충분하며 경화시간이 적당하고 값도 저렴해야 한다. 또 구강내에서 제거할 때 영구변형이나 파절되지 않는 충분한 강도와 크기의 정확성도 있어야 하며 자극이나 독성이 없고 인체에 안정성이 있고 모형재와 친화성이 있으며 보관중에도 변질해서는 안된다. 그러나 인상재는 서로 상이한 특성이 있고 장단점이 각각 다르므로 모든 조건에 일치하는 인상재는 거의 없다. 따라서 여러 인상재중에서 가장 적합한 인상재를 선택하는 것이 중요한 과정이다. 즉 인상재의 특성과 응용을 알고 선택할땐 보다 정밀한 모형을 얻을 수 있다. 기록에 의하면 18~19세기경에 최초로 인상용 왁스를 사용한 이래 19세기 중엽에 인상용 석고, 1925년에 agar, 1930년 ZOE, 1945년 앨지네이트, 1957년 실리콘, 1967년 polyether 및 1975년 부가중합형 실리콘이 사용되었으며 인상재가 유연성과 탄성이 있는가 경고하며 비탄성인가 또는 온도변화와 화학반응으로 경화되는 가에 따라서 ZOE paste, 인상용 석고, 인상용 왁스, 인상용 콤파운드, 수성콜로이드(agar, 앨지네이트), polysulfide, 실리콘(축중합형, 부가중합형) 및 polyether 인상재등 10여종으로 분류된다.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.506-511
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• 2008

In this study sol-gel and combustion process was surveyed for the preparation of the red $Y_2O_3$: Eu phosphor, and the properties of phosphor was considered. Chelation and hydrolysis in amorphous citrate sol-gel process were completed in initial reaction stage, and water-forming condensation was superior to organic acid-forming condensation. The mole ratio of citric acid to metal ion had to be above to for the progress of sol-gel process. The dried gel powders are mostly amorphous, and crystallize completely at $700^{\circ}C$, and the crystallinity increases with increasing calcining temperature. The luminescence property of the phosphor was analyzed by measuring the emission spectra. The luminescence intensity increases when the calcination temperature and concentration of metal ions in solution increase.

• Journal of Adhesion and Interface
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• v.16 no.2
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• pp.76-82
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• 2015

W/O emulsions were prepared from the aqueous solution containing NIPAAm, MBA, and APS in the continuous phase of toluene and mineral oil mixture with HMP and Span80 by using SPG membrane emulsification, and followed by the formation of PNIPAAm hydrogel microspheres through UV photopolymerization. As the ratio of mineral oil to toluene increased in the continuous phase, both particle size of the hydrogel increased and density of PNIPAAm polymer in the hydrogel particle increased, and which significantly affected swelling/deswelling ratio ($V/V_o$) with temperature change around VPTT. When the polymerization temperature was below LCST ($20^{\circ}C$), PNIPAAm hydrogel showed filled particle morphology; however, it was turned out to hollow particle morphology with thick shell layer with $40^{\circ}C$. Both density of PNIPAAm and gel content of the hydrogel increased with the increase in MBA concentration.

• Elastomers and Composites
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• v.44 no.1
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• pp.55-62
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• 2009

In this study, investigation on the polymerization characteristics of isoprene through nitroxide mediated controlled/"living" radical polymerization techniques was attempted. In the presence of acetol, linear increase of isoprene conversion with time and low polydispersities of the resulting polymers ($M_w/M_n$ < 1.5) were observed, which suggest successful controlled/"living" radical polymerization of isoprene. The microstructure of the resulting polyisoprene was composed of $\sim$ 22% of 3, 4, $\sim$30% of 1, 4-cis and $\sim$ 48% of 1, 4-trans. The optimum polymerization temperature was 145 $^{circ}C$, below which no significant polymerization behavior was observed. Non-cyclic nitroxide, such as di-tert-butyl nitroxide (DTBN) could not mediate the polymerization, whereas cyclic nitroxides (2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (TEMPO) and 4-oxo-2, 2, 6, 6-tetramethyl-1-peperidine 1-oxyl (oxoTEMPO)) were successfully employed for the polymerization. However, isoprene dimerization reaction through Diels-Alder process was also observed at the given polymerization condition, which afforded a significant amount of limonene. Isoprene thermal autoinitiation was also possible, which was, however, considered to be not significant under the given polymerization condition.