• Title/Summary/Keyword: polymerization rate

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Effect of Protonic Acids on the Reaction Rate in Chemical Polymerization of Polyaniline (폴리아닐린의 화학적 중합 시 반응속도에 미치는 양성자산의 영향)

  • Hong, Jang-Hoo;Jang, Beom Soon
    • Applied Chemistry for Engineering
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    • v.16 no.5
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    • pp.684-688
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    • 2005
  • Aniline was polymerized in various protonic acid (HF, HC1, HBr, HI, $H_2SO_4$) aqueous solutions with different acidity. During the reaction, the dimer formation and the reaction rate were examined as functions of acidity (pH) and the size of counter ions. Open-circuit potential measurements were carried out to investigate the effect of protonic acid on the reaction rate. The results showed that polymerization rate in HF aqueous solution was very slow and polymerization did not occur in HI aqueous solution. These results were explained in terms of acidity and power of oxidation. The ratio of formation of dimers varied with the kind of protonic acid, and the results were explained with the nucleophilicity, solvation effect, and mobility of counter ions.

Permeation Properties of Surface Modified Nanofiltration Membrane (표면 개질된 나노복합막의 투과 특성)

  • Tak Tae-Moon;Park Hyung-Kiu;Jang Gyung-Gug
    • Membrane Journal
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    • v.14 no.3
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    • pp.207-217
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    • 2004
  • In this study, we prepared nanofiltration membrane by applying the interfacial polymerization method as a way of manufacturing composite membranes. We have examined the effects of various preparation factors such as monomer concentration and composition, thermal curing condition, post treatment condition. In addition to preparation conditions, we also monitored the effects of operation conditions such as feed solution concentration and operation pressure on the permeation properties of the resulting nanofiltration membrane. We intended to increase the permeation rate of nanofiltration membrane by the enlargement of effective surface area using additives during interfacial polymerization step. With increasing the monomer concentration, membrane permeation rate are decreased with maintaining almost constant rejection. With respect to curing condition, with increasing the curing temperature both permeation rate and rejection are decreased. With increasing the ratio of MPD in amino monomer composition, permeation rate decreased drastically with high rejection. With increasing the feed solution concentration, both permeation rate and rejection decreased. Both permeation rates and rejection increased with increasing the operating pressure. Nanofiltration membrane have higher surface roughness with increasing additive concentration in the case of using MPD contained amine composition than using piperazine alone. Permeation rates are much lower than the nanofiltration membrane prepared by piperazine.

The Study of Encapsulation Technique for Microcapsule Using Core Materials with Low Melting Point (저융점을 가진 Core 물질을 이용한 내구성 Microcapsule 제조 기술)

  • Noh, Kun-Ae;Gang, Eu-Gene;Kim, Sang-Hern
    • Journal of the Korean Applied Science and Technology
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    • v.18 no.4
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    • pp.273-284
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    • 2001
  • A series of microcapsule were synthesized by using several PCM(Phase Change Material) as a core material and gelatin/arabic gum, melamine/formaldehyde as a shell material. Coacervation technique and in situ polymerization were adopted in synthesizing microcapsules. In the microencapsulation by coacervation, tetradecane and octadecane were used as core materials. In the microencapsulation by situ polymerization tetradecane, pentadecane, hexadecane, heptadecane, octadecane, and nonadecane were used as core material. The synthesized microcapsule was examined to observe the shape of the microcapsule. The particle size analysis was performed by particle size analyzer. The thermal properties(e.g. melting point, heat of melting, crystallization temperature, heat of crystallization, differences between melting point and crystallization temperature) were obtained by DSC(Differential Scanning Calorimeter). The stirring rate effect was investigated during the microencapsulation. It was found that with increasing the stirring rate much smaller microcapule was produced. However, this did not necessarily lead to formation of spherical microcapsule.

Study on the Frictional Properties of Nylons Synthesized by Varying Catalyst Content (촉매 함량 변화에 따라 합성된 나일론의 마찰 특성에 관한 연구)

  • Chung, Dae-Won;Kang, Suk-Choon
    • Polymer(Korea)
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    • v.29 no.1
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    • pp.14-18
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    • 2005
  • Nylons were synthesized by anionic polymerization of ${\varepsilon}$--caprolactam while varying the content of catalyst. Polymerization rates, molecular weights, mechanical properities and frictional properties of the nylons were investigated. As the ratio of catalyst to initiator was increased up to 1.0%, the polymerization rate, conversion and molecular weight were found to increase, and mechanical properties except impact strength were improved. Frictional properties were affected mainly by tensile strength and hardness. According to the study on the friction coefficient, product of stress (P) and velocity (V), PV limit, and abrasive wear rate, nylon synthesized at 1.0% of the ratio of catalyst to initiator showed the best performance for sliding machine elements.

Analysis of Runaway Reaction at Styrene Suspension Polymerization (스티렌 현탁 중합반응에서 폭주반응 해석)

  • 박형일;신석주;이헌창;장서일;김태옥
    • Journal of the Korean Society of Safety
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    • v.17 no.3
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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.

Synthesis of arsenic adsorbent using graft polymerization

  • SEKO Noriaki;TAMADA Hasao
    • Proceedings of the Membrane Society of Korea Conference
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    • 2004.11a
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    • pp.199-203
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    • 2004
  • Fibrous arsenic (As) adsorbent was synthesized by loading zirconium (Zr) on fibrous phosphoric adsorbent that was directly synthesized by radiation-induced graft polymerization of 2-hydroxyethyl methacrylate phosphoric acid on polyethylene-coated polypropylene nonwoven fabric. Zirconium reacted with phosphoric acid grafted in the polyethylene layer. Zirconium density of the resulting adsorbent was 4.1 mmol/g. The breakthrough curve of As(V) adsorption was independent of the flow rate up to $1300\;h^{-1}$ in space velocity. The total capacity of As(V) was 2.0 mmol/g-adsorbent at pH of 2. The adsorbed Zr(IV) could be evaluated by 0.4 M sodium hydroxide solution because negligible Zr(IV) could be found in the eluted solution.

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A study on the E-beam resist characteristics of plasma polymerized styrene (플라즈마중합 스티렌 박막의 e-beam 레지스트 특성에 관한 연구)

  • 이덕출;박종관
    • Electrical & Electronic Materials
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    • v.7 no.5
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    • pp.425-429
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    • 1994
  • In this paper, we study on the plasma polymerized styrene as a negative electron-beam resist. Plasma polymerized thin film was prepared using an interelectrode inductively coupled gas-flow type reactor. We show that polymerization parameters of thin film affect sensitivity and etching resistance of the resist. Molecular weight distribution of plasma polymerized styrene is 1.41-3.93, and deposition rates of that are 32-383[.angs./min] with discharge power. Swelling and etching resistance becomes . more improved with increasing discharge power during plasma polymerization. Etch rate by RIE is higher than that by plasma etching.

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Preparation of Micron Size Poly(n-Butyl Acrylate) Latex Particle by Sequential Seeded Emulsion Polymerization (연속적 Seed 유화중합법에 의한 마이크론 크기의 Poly(n-Butyl Acrylate) 라텍스입자 제조)

  • Kim, Jee-Hoon;Suh, Soong-Hyuck;Nam, Wan-Woo;Kim, Kyung-Chan;Kang, Shin-Won;Ha, KiRyong
    • 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.

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Thermal Hazards of Polystyrene Polymerization Process by Bulk Polymerization (벌크 중합법에 의한 폴리스티렌 중합공정의 열적위험성)

  • Han, In-Soo;Lee, Jung-Suk;Lee, Keun-Won
    • Journal of the Korean Institute of Gas
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    • v.17 no.4
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    • pp.1-8
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    • 2013
  • The aim of this study is to assess thermal hazards of polystyrene polymerization process by bulk polymerization with accelerating rate calorimeter(ARC) and Multimax reactor system(MM). From this study, we found out that the polymerization process should be operated at reaction temperature of $120^{\circ}C{\sim}130^{\circ}C$. At reaction temperature over $130^{\circ}C$, there was a runaway reaction hazard due to the temperature control failure following a viscosity increase of reaction products. With a cooling failure of a reactor in the early stage of process operation at the reaction temperature ($120^{\circ}C{\sim}130^{\circ}C$), there was a high thermal hazard of burst of a reactor's rupture disk or explosion of a reactor caused by the rapid rise of temperature and pressure to $340^{\circ}C$, 5.3 bar respectively within 30 - 50 minutes.