• Biotechnology and Bioprocess Engineering:BBE
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• 제11권6호
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• pp.503-509
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• 2006

Molecularly imprinted polymeric microbeads (MIPMs) were prepared by the suspension and modified suspension polymerization methods using D-phenylalanine as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, toluene as the porogen, polyvinyl alcohol as the stabilizer, and sodium dodecyl sulfate as the surfactant. The addition of a surfactant to the conventional suspension polymerization mixture decreased the mean particle size of the MIPMs and increased the adsorption selectivity. For the modified suspension polymerization method, the mean particle size of the MIPMs was smaller than the particle size of MIPMs prepared via conventional suspension polymerization. Moreover, the adsorption selectivity improved considerably compared to the adsorption selectivities of MIPs reported previously.

• Fibers and Polymers
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• 제5권1호
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• pp.75-81
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• 2004

To obtain high molecular weight (HMW) poly(methyl methacrylate) (PMMA) with high conversion, methyl methacrylate (MMA) was polymerized in suspension using a room temperature initiator, 2,2'-azobis(2,4-dimethylvaleronitrile) (ADMVN), and the effects of polymerization conditions on the polymerization behavior of MMA and the molecular parameters of PMMA were investigated. On the whole, the experimental results well corresponded to the theoretically predicted tendencies. These effects could be explained by a kinetic order of ADMVN concentration calculated by an initial rate method and an activation energy difference of polymerization obtained from the Arrhenius plot. Suspension polymerization at 25℃ by adopting ADMVN proved to be successful in obtaining PMMA of HMW (number-average degree of polymerization (P/sub n/): 30,900-36,100) and of high yield (ultimate conversion of MMA into PMMA: 83-93 %) with diminishing heat generated during polymerization. The P/sub n/ and lightness were higher and polydispersity index was lower with PMMA polymerized at lower temperatures.

• Fibers and Polymers
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• 제6권4호
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• pp.277-283
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• 2005

In order to prepare high molecular weight poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres, methyl methacrylate was suspension-polymerized in the presence of silver nanoparticles at low temperature with 2,2'-azobis(2,4-dimethylvaleronitrile) as an initiator. The rate of conversion was increased by increasing the initiator concentration. When silver nanoparticles were added, the rate of polymerization decreased slightly. High monomer conversion (about $85\%$) was obtained in spite of low polymerization temperature of $30^{\circ}C$. Under controlled conditions, PMMA/silver microspheres with various number-average degrees of polymerization (6,000-37,000) were prepared. Morphology studies revealed that except for normal suspension microspheres with a smooth surface, a golf ball-like appearance of the microspheres was observed, due to the migration and aggregation of the hydrophilic silver nanoparticles at the sublayer beneath the microsphere's surface.

• Carbon letters
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• 제14권1호
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• pp.45-50
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• 2013

Polyacrylonitrile (PAN) copolymers of different molecular weights were synthesized by a suspension polymerization and precipitation polymerization method. The rheology behaviors of the synthesized PAN copolymers were investigated in relation to their molecular weight, solid content and melting temperature. The influence of "historical effects" on the spinning solution of PAN was studied by analyzing the laws of viscosity considering the diversification time and temperature. The viscosity disciplines of each spinning solution conformed well to the rheological universal laws in a comparison of the suspension polymerization product with that of precipitation polymerization. Viscosity changes in the swelling process of dissolution were gentler in the suspension polymerization product; a small amount of water will quickly debase the solution viscosity, and high-speed mixing can greatly shorten the time required by the spinning solution to reach the final viscosity.

• Fibers and Polymers
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• 제7권3호
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• pp.229-234
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• 2006

Poly(vinyl acetate) (PVAc)/poly(vinyl alcohol) (PVA)/montmorillonite (MMT) clay nanocomposite microspheres with a core/shell structure have been developed via a suspension polymerization approach. In order to prepare the PVAc/ MMT and PVAc/PVA/MMT nanocomposite microspheres, which are promising precursor of PVA/MMT nanocomposite microspheres, suspension polymerization of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium bromide, was mixed with the MMT in the monomer phase prior to the suspension polymerization. The rate of conversion decreased with an increase in MMT concentration. The incorporation of MMT into the PVAc was verified by FT-IR spectroscopy. Organic vinyl acetate monomers were intercalated into the interlayer regions of organophilic clay hosts and followed by suspension polymerization. Partially saponified PVA/MMT nanocomposite microspheres with a core/shell structure were successfully prepared by heterogeneous saponification.

• 폴리머
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• 제35권5호
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• pp.390-394
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• 2011

현탁중합에 의한 폴리(비닐 아세테이트)((poly(vinyl acetate)(PVAc))/은 미세입자 제조시 사용된 은 나노입자가 중합속도 및 PVAc 미세입자의 형태에 미치는 영향을 고찰하였다. 주사전자현미경, 투과전자현미경, X선 회절, 원자흡수분광분석법을 이용하여 제조된 미세입자의 형태와 특성을 분석한 결과, 사용된 은 나노입자 표면의 친수성 정도와 계면활성제의 농도에 따라 미세입자의 표면이 골프공 표면처럼 오목해지거나 다양한 형태의 중공 구조를 가지는 PVAc/은 미세입자가 제조됨이 관찰되었다. 계면활성제로 개질된 은 나노입자를 이용하여 중합한 경우에 중합속도가 약간 증가하였으며, 80% 이상의 전환율을 가지는 PVAc/은 미세입자를 제조할 수 있었다.

• Korean Chemical Engineering Research
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• 제48권2호
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• pp.212-217
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• 2010

본 연구에서는 유기현탁제로 폴리비닐알콜(PVA: Poly(vinyl alcohol)을 사용하여 현탁중합토너를 제조하였다. 스타이렌과 부틸아크릴레이트 모노머를 동시에 사용하고 카본블랙을 첨가하여, 좁은 입경분포를 갖는 미세 구형 중합토너를 제조하였다. 최적의 현탁중합조건을 설정하기 위하여 카본블랙이 배제된 예비입자 중합실험을 먼저 수행하였다. 예비입자는 다양한 중합조건에서 제조하였으며, 각각의 특징을 비교 분석하여 최적의 중합조건을 결정하였다. 최적화된 중합조건을 선택하여 제조된 흑색중합토너는 입경 및 형상이 우수하였으며 유리전이온도도 $53.6^{\circ}C$인 것으로 나타나 열적 특성 및 인쇄특성도 우수한 것으로 관찰되었다.

• 한국인쇄학회지
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• 제20권1호
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• pp.65-78
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• 2002

The suspension polymerization of styrene was carried out to obtain the narrow-size distribution of particle by using poly(vinyl alcohol) (PVA) as suspension stabilizer according to the degree of hydrolysis and the molecular weight. The stabilizing properties of suspension are also dependent on the interfacial tension of aqueous solution when PVA is added. When the polymerization process was carried out with low hydrolyzed PVA, it gave single, well-defined particles, while high hydrolyzed PVA gave clusters. The size of particle produced in this study ranged between 5${\mu}{\textrm}{m}$ and 10${\mu}{\textrm}{m}$. The suspending agent, PVA, influences on the drop size and drop stability, When the molecular weight of PVA is increased, the drop size decreases and the drops become more stable toward coalescence. An increase in the PVA concentration decreases the mean drop size and narrows the drop size distribution.

• Macromolecular Research
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• 제8권6호
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• pp.247-252
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• 2000

Suspension polymerizations of styrene were conducted in the aqueous phase with tricalcium phosphate (TCP) as a stabilizer and $\alpha$, $\alpha$'-azobis(isobutyronitrile) (AIBN) as an initiator. Various amounts of initiator and stabilizer were selected and the reaction was carried out at a selected temperature between 60 to 80 $\^{C}$. It was found that the combination of 5 wt% stabilizer and 2.427$\times$10$\^$-3/ mol/L of costabilizer is the minimum amount for suspension polymerization reaction to produce particles in the aqueous phase. Particles were found to be polydisperse in diameter, regardless of reaction conditions. Class transitions were observed to be around 95$\^{C}$, nearly independent of reaction temperature and initiator. Homogenizer was found to be essential in forming particles in the proximity of tens of micrometers in diameter in suspension polymerization with TCP as stabilizer.

• 한국안전학회지
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• 제17권3호
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• pp.81-89
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• 2002

The runaway reaction was analyzed experimently and theoretically at the batch styrene suspension polymerization process. In the experiments, the reaction temperature with time was measured at various experimental conditions. According to the experimental results, the risk of the runaway reaction was increased with increasing the ratio of the monomer(styrene, M) to the dispersion medium(water, W), the concentration of the initiator(BPO), and the monomer mass, respectively. And simulation results showed that the runaway reaction was significantly affected by the reaction rate constant of the propagation and that the phenomena of the runaway reaction occurred at about 70% conversion. Also, we found that the runaway reaction did not occur under the operating condition of below 0.5 for M/W, approximate 3 wt% BPO, and below 75$^{\circ}C$ for the cooling temperature.