• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.669-675
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• 2008

Carbon black has been widely used in composites, tonor resin, and ink materials. Since carbon black readily agglomerates, it is important to disperse carbon black in real applications. Aiming to improve dispersion stability, carbon black was chemically oxidized to possess hydroxyl groups using a phase transfer catalyst at room temperature. The modified carbon black (CB-OH) was grafted by a silane coupling agent, p-methylacryloxypropyltrimethoxysilane, to carry teminal vinyl groups. The modified carbon black was subsequently used in miniemulsion polymerization to achieve encapsulted core-shell structure. Finally, well-encapsulated carbon black by polymer was obtained in the size range of 100-500 nm. Throughout the polymerization, the effects of surface modification, types of monomers, initiators, and emulsifiers were investigated.

• Elastomers and Composites
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• v.37 no.1
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• pp.31-38
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• 2002

Polymerization of carboxylated styrene-butadiene latex takes longer time than that of acrylic emulsion due to delocalization of radical in butadiene unit having conjugated double bond. A latex stability is the most important properties owing to use intact without separating polymer from base latex. For reducing polymerization time without decreasing any properties of latex, carbon tetra-chloride which has been used as the most popular chain transfer agent was replaced to combination of tert-dodecylmercaptane and ${\alpha}$-methylstyrene dimer. The replacement yielded reducement or 2 hr in polymerization time. In the increment step, charge amount of acrylic acid was limited to 0.3 part to restrain viscosity enhancement. Just after initial step, addition of 0.1 part acrylamide prevent polymer chain from diffusing between two region followed by giving hardness and final good adhesive force to latex particles.

• Clean Technology
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• v.14 no.1
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• pp.21-28
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• 2008

The properties of the dispersion of the red, green, and blue pigments were investigated for the manufacture of the millbase of LCD color filters. Their physical properties and viscosity were controlled to apply to the screen printing in order to substitute the existing photolithography method. The best dispersion properties were obtained with dispersant BYK-2000 and monomer EB-140. The millbase was pre-mixed at 500 rpm for 30 min, and dispersed at 4000 rpm for 5 - 6 hour by Torus Mill. The resulting particle sizes were $100{\sim}110\;nm$ for red, $50{\sim}70\;nm$ for green, and $60{\sim}80\;nm$ for blue. When the millbase viscosity was 200-300 cps in the low viscosity formulation, an efficient impact of the beads on pigments was achieved. The dispersion properties were confirmed from the rheological behavior and color characteristics.

• Journal of the Korean Vacuum Society
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• v.6 no.3
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• pp.213-219
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• 1997

The plasma polymerized styrene films were prepared by using an inter-electrode capacitively coupled gas-flow-type reactor, and the effects of plasma polymerization condition on the molecular weight distribution were investigated by Fourier Transform Infrared (FT-IR), Pyrolysis Gas Chromatography(PyGC), Differential Scanning Calorimetry(DSC) and Gel Permeation Chromatography(GPC). From the above results, the very cross-linked films different from chemical characteristics of the starting monomer were taken out, and it is realized that the molecular structure, cross linking density, and molecular weight distribution could be controlled by changing the parameters such as deposition pressure, deposition power and gas flow rate. Accordingly, it is suggested that plasma polymerization method performed by inter-electrode capacitively coupled gas-flow-type reactor has good characteristics for manufacturing the functional organic thin films which can be applied in sensors, opto-electric device, photo-resist by changing the polymerization parameters.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.52-52
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• 2011

PLA 섬유는 폴리머의 주성분이 옥수수에서 추출한 모노머를 중합한 화학섬유가 아닌 인체친화적인 식물성 소재이며 생분해성이 좋은 친환경 소재로 최근 주목받고 있는 섬유소재이다. 본 연구에서는 아토피완화용 여러 섬유 구조체 개발에서 사용되는 섬유소재중 PLA 원사에 항균성 물질을 혼입하여 PLA 항균사 제조를 위한 연구를 수행하였다. PLA Grade의 점도가 낮아질수록 Grade별 용융 지수값은 차이를 나타내지만 방사온도 $230^{\circ}C$를 변곡점으로 하여 용융점도가 급격히 변하였으며, 특히 방사온도 $240^{\circ}C$의 경우 용융지수가 100을 넘어가고 폴리머의 색깔이 황갈색을 띄어 폴리머의 열분해가 많이 일어났을 것으로 판단되었다. PLA의 적정 방사온도 구간은 $210{\sim}225^{\circ}C$ 구간이 최적이며 그 이상에서는 Color 변화 및 물성 저하가 나타나는 것으로 판단되었다. 항균성 PLA 섬유를 제조하기 위하여 피톤치드계 유기항균제를 이용하였으며, 피톤치드에 기능성 엘라스토머를 사용하여 Capsulation을 진행하였다. 이러한 유기항균제 Powder의 경우 비중이 낮아 표면적로 인하여 마스터배치 칩을 만드는 공정에서 잘 혼합되지 않는 문제점이 발생하였으나, 피톤치드의 함량을 조절하여 PLA와의 마스터배치 칩 제조를 시험하였다. 압출온도와 토출량, Screw 조건(Mixing, Zone)을 시험하여 적정 조건을 설정하였다. 항균사 PLA 섬유는 Sheath/Core 복합방사 형태와 단독사 형태의 2가지 Type을 제조하였다. Sheath/Core 복합방사 폴리머 구성은 Sheath부에 PLA항균사, Core부에 PLA 또는 저융점 PET를 사용하였다. Core부의 폴리머는 제사성에 큰 영향을 미치지 않았으나, 항균 마스터배치의 함량이 증가할수록 Pack압 상승이 급격히 일어나는 단점이 나타났다. 항균제 5% 정도가 혼입되어 있는 경우에 2.1 이상의 정균활성치와 99.8% 정도의 정균감소율 성능을 나타내었다. PLA 단독사의 경우, 항균제 최적 함량은 3% 이상으로 정균활성치 5.5 이상, 정균감소율 99.9%의 우수한 항균특성을 나타내었다.

• Applied Chemistry for Engineering
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• v.3 no.3
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• pp.499-506
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• 1992

Copolymer of Styrene and GMA(glycidyl methachylate), having reactive ratios of $r_1=0.53$, $r_2=0.44$, was synthesized in dioxane using AIBN as free radical initiator. Followed by the reaction of ethylene diamine with copolymer PGS, amine groups were introduced to the PGS(NPGS). The composition of copolymer was determined by elemental analyzer. Poly(glycidyl methacrylate) (PGMA) was obtained in benzene using AIBN as free radical initiator. The NPGS-PGMA blend of 50/50 composition was prepared by mixing these polymers in THF at $65^{\circ}C$. Glass transition temperature (Tg) of NPGS-PGMA blend was measured by DSC. The blend showed a single Tg. Accordingly, it was clear that the NPGS was compatible with PGMA. An intermolecular reaction between amine groups of NPGS and epoxy groups of PGMA imparts compatibility in the NPGS-PGMA blend. When the NPGS-PGMA blend was added to the incompatible PS-PGMA blend, PS-PGMA blend showed Tg change. Scanning Electron Micrograph(SEM) showed a fine morphology in this blend. Consequently, it was apparent that the NPGS-PGMA blend acted as a compatibilizer for the PS-PGMA blend.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3351-3356
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• 2014

Recently, Importance of studying based on biomass materials have increased due to the concern about plastic waste problems. Cellulose acetate butyrate (CAB) is a potential alternative to petroleum-based plastics because of its biodegradable property. Poly(ethylene-co-isosorbide terephthalate) (PEIT) is bio-based plastic, produced by isosorbide monomer. In this study, CAB/PEIT blends were prepared by solution blending to improve thermal stability of CAB. CAB and PEIT were dissolved in chloroform, and then precipitated in ethanol. To evaluate the compatibility of CAB/PEIT blends, the morphology and glass transition behaviors were analyzed by FE-SEM and DMA, respectively. TGA results revealed the improved thermal stabilities of the PEIT-rich and 50:50 compositions. No new or changed crystal structures were observed in the XRD result. Finally, CAB/PEIT solution blends showed good compatibility in overall compositions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.385-393
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• 2019

Potential fire, explosion and safety hazards exist in medium- or small-scale chemical plants using radical batch reaction processes due to the various conditions of materials, works or products. To minimize the potential damage, a study was conducted on qualitative hazard analysis using the HAZOP technique, which is a typical method for a qualitative risk assessment and analysis of the potential risks encountered in these chemical plants. For this purpose, a domestic chemical plant, which produces the acrylic resin by a radical batch reaction process, was selected and a risk assessment and analysis according to the procedure of HAZOP method was performed for the process. As the result of the study, to prevent the hazard, the input of inert gas and the installation of a pressure gauge were indispensable. In addition, the initiator and monomer should also be separated, and inhibiting substances and equipment are also necessary to prevent a runaway reaction.

• Journal of the Korean Applied Science and Technology
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• v.36 no.1
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• pp.305-311
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• 2019

The acrylic copolymer was designed and prepared for soft lens with high content. The copolymers were prepared using 2-hydroxyethyl methacrylate(HEMA) as a monomer and ethylene glycol dimethacrylate(EGDMA), glycerol dimethacrylate(GD), or glycerol 1,3-diglycerolate diacrylate (GDD) as a cross linking agent. The water content for high water content lens was 46%, which was higher compared to general purpose of 36%. The contact angle decreased from 38.6 to 34.4, which appears hydrophilic surface. The tensile strength decreased from 0.1 Mpato 0.08, then again to 0.05 as hydrophilic properties of cross linking agents increased. No phase separation was observed in the cross section of lens using scanning electron microscope. The real-time infrared technique was used in photo-polymerization. The initial polymerization rate increased from 0.6 to 0.9, depending on crosslinking agent.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.241-246
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• 2019

In this paper, reactive surfactants were synthesized by using acrylic acid or 3-butenoic acid as nonionic surfactants, polyoxyethylene(23) lauryl ether (Brij 35) and polyoxyethylene(20) stearyl ether (Brij S20). The synthesis of surfactants was confirmed by FT-IR and $^1H$-NMR. The surface tension, emulsifying property, and foam power and stability were also measured. The surface tension value was 35~41 dyne/cm at an critical micelle concentration (cmc) which was measured as $1.0{\times}10^{-4}{\sim}9.7{\times}10^{-5}mol/L$ using a surface tension method. The emulsifying power of synthesized surfactant was measured with benzene, soybean oil and monomer. Also, the initial height of the bubbles and the height after 5 minutes were measured and the values were compared with each other.