• 제목/요약/키워드: Crosslinking temperature

검색결과 237건 처리시간 0.028초

저온 플라즈마 공정의 복합막 제조에의 응용 (Application of Low Temperature Plasma Treatment to the Fabrication of Thin Film Composite Membrane)

  • 김현일;김성수;전배혁
    • 한국막학회:학술대회논문집
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    • 한국막학회 1998년도 추계 총회 및 학술발표회
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    • pp.120-122
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    • 1998
  • 현재 상업화되어있는 RO membrane으로는 크게 asymmetric membrane과 composite membrane으로 구분될 수 있다. Asymmetric membrane의 소재로는 Cellulose acetate나 Cellulose triacetate와 같은 것들이 사용되며 현재에도 많이 사용되고 있으나, 보다 더 우수한 성능을 갖는 분리막을 제조하기 위해 현재에는 주로 composite membrane 형태로 제조된다. 대부분의 composite membrane은 계면중합에 의해 제조되는데 대표적인 membranem으로는 FT-30이 있다. 이 밖에도 support의 표면을 직접 플라즈마 처리하여 복합막을 제조하는 공정이 있으며 polyactrylonitrile과 같은 membrane이 이에 속한다. 플라즈마 처리된 복합막은 처리 대상에 크게 영향을 받지 않고 support 표면에 crosslinking의 형태로 형성되기 때문에 active layer가 매우 안정하며 따라서 우수한 물리화학적 성질을 기대할 수 있다. 이밖에도 분리막 표면을 친수성 단량체로 플라즈마 처리함으로써 분리막 표면에 친수성을 부여하거나 관능기를 도입함으로써 불활성 표면을 활성화 시킬 수도 있는 등의 여러가지 장점을 가지고 있다.

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Self-Diffusion of THO within Tactic Poly(2-hydroxyethyl methacrylate) Membranes

  • Kim, Hye-Kyeong;Jhon, Mu-Shik
    • Bulletin of the Korean Chemical Society
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    • 제4권3호
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    • pp.128-132
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    • 1983
  • The self-diffusion experiment of water was performed across two series of tactic poly(2-hydroxyethyl methacrylate), P(HEMA) membranes prepared by crosslinking with various amount of hexamethylene diisocyanate (HMDIC). The tagging material was tritium hydroxide (THO) and the efflux of THO was counted on a Liquid Scintillation Counter. The transport data of THO show that the permeability decreases as the amount of HMDIC increased from 2.5 to 10 mole % and the self-diffusions coefficient shows a parallel trend with it. The diffusivity data was discussed in terms of the change of water structural orderliness within membranes. Using the relation between viscosities and diffusivities derived from Eyring's absolute rate theory, the corresponding viscosities of water within two series of tactic P(HEMA) membranes were obtained. From this, it is seen that the viscosity of water within tactic P(HEMA) membranes may have the same values with those of supercooling water whose temperature ranges from -28 to -$36^{\circ}C.$.

Synthesis of Highly Crosslinked Temperature-resistant Poly(vinyl ethers) by Free Radical Polymerization

  • 이주연;김지향
    • Bulletin of the Korean Chemical Society
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    • 제19권8호
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    • pp.851-856
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    • 1998
  • 2,4-Di-(2-vinyloxyethoxy)benzylidenemalononitrile (2a), methyl 2,4-di-(2-vinyloxyethoxy)benzylidenecyanoacetate (2b), 3,4-di-(2-vinyloxyethoxy)benzylidenemalononitrile (4a), and methyl 3,4-di-(2-vinyloxyethoxy)benzylidenecyanoacetate (4b), 2,5-di-(2-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl 2,5-di-(2-vinyloxyethoxy)benzylidenecyanoacetate (6b) were prepared by the condensation of 2,4-di-(2-vinyloxyethoxy)benzaldehyde (1), 3,4-di-(2-vinyloxyethoxy)benzaldehyde (3), and 2,5-di-(2-vinyloxyethoxy)benzaldehyde (5) with malononitrile or methyl cyanoacetate, respectively. Trifunctional divinyl ether monomers 2, 4 and 6 were polymerized readily by free radical initiators to give optically transparent swelling poly(vinyl ethers) 7-9. Polymers 7-9 were not soluble in common organic solvents such as acetone and DMSO due to crosslinking. Polymer 7-9 showed a thermal stability up to 300 ℃ in TGA thennograms.

Preparation and Thermal Properties of Enaryloxynitriles End-Capped Polymer Precursors

  • 길대수;공명선
    • Bulletin of the Korean Chemical Society
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    • 제21권6호
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    • pp.557-561
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    • 2000
  • Various enaryloxynitriles-terminated reactive polymer precursors containing rigid aromatic units were prepared from various diamines and 1-(p-formylphenyl)-1-phenyl-2,2-dicyanoethene (1). Arylate end-capped model compounds linked with azomethine bond were also prepared by reacting p-formylphenyl benzoate with diamines to compare the curing ability. The oligomers were highly soluble in polar aprotic solvents such as N,N-dimethylformamide, dimethylsulfoxide and N-methyl-2 -pyrrolidinone. They generally showed an exothermic curing process between $280-350^{\circ}C$, attributable to the thermal crosslinking of the dicyanovinyl group in DSC analysis, and no weight loss at curing temperature. Upon heating the polymer precursors, heat-resistant and insoluble network polymers were obtained. Thermogravimetric analyses of the precursors containing rigid aromatic units showed thermal stability with a 77-92% residual weight at $500^{\circ}C$ under nitrogen.

Physicochemical and Electrical Characterization of Polyaniline Induced by Crosslinking, Stretching, and Doping

  • 류광선;장순호;강성구;오응주;요철현
    • Bulletin of the Korean Chemical Society
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    • 제20권3호
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    • pp.333-336
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    • 1999
  • The polyaniline films with various insoluble parts are fabricated. The oxidation state (1-y) of these polyaniline is 0.53 and 0.54, respectively. To control the interchain and intrachain interaction of the polymer, the polyaniline films are stretched with appropriate ratio. The insoluble part of polyaniline synthesized at room temperature (low molecular weight) is 12%-76% and that of polyaniline synthesized at 0 'IC (intermediate molecular weight) is 65%-89%. The low molecular weight polyaniline films with various drawing ratios have amorphous structure. In the intermediate weight polyaniline films, the crystallinity of films increases with drawing ratio as well as insoluble part. The difference of the insoluble part affects electrical conductivity which is increased dramatically with draw ratio. In particular, the higher insoluble part caused greater increase in electrical conductivity.

2 -관능성 에폭시 수지 블렌드의 굴곡 특성과 열 안전성 (Flexural Properties and Thermal Stability of Bifunctional/Tetrafunctional Epoxy Blends)

  • 유희열;이재락;이종문
    • 한국재료학회지
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    • 제4권1호
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    • pp.75-80
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    • 1994
  • 2-관능성 DGEBA-4-관능성 TGDDM 블렌드를 DDM으로 경화시킨 경호물의 굴곡 특성과 열 안정성을 혼합비에 대하여 조사하였다. 굴곡 탄성율과 유리 전이 온도는 TGDDM이 증가 될수록 증대되었고, 20-40 중량%의 TGDDM조성에서 불연속적으로 변화하는데, 이것은 이 저성 부근에서 ductile/brittle의 구조적 상변화가 일어나고 있기 때문인 것으로 추정된다. TGDDM성분이 증가될수록 최대 열분해 온도는 고온쪽으로 shift되는 경향을 보이지만, 분해에 대한 활성화 에너지는 오히려 감소했다.

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Synthesis and Characterization of Thermosensitive Nanoparticles Based on PNIPAAm Core and Chitosan Shell Structure

  • Jung, Hyun;Jang, Mi-Kyeong;Nah, Jae-Woon;Kim, Yang-Bae
    • Macromolecular Research
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    • 제17권4호
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    • pp.265-270
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    • 2009
  • Noble thermosensitive nanoparticles, based on a PNIPAAm-co-AA core and a chitosan shell structure, were designed and synthesized for the controlled release of the loaded drug. PNIPAAm nanoparticles containing a carboxylic group on their surface were synthesized using emulsion polymerization. The carboxylic groups were conjugated with the amino group of a low molecular weight, water soluble chitosan. The particle size of the synthesized nanoparticles was decreased from 380 to 25 nm as the temperature of the dispersed medium was increased. Chitosan-conjugated nanoparticles with $2{\sim}5$ wt% MBA, a crosslinking monomer, induced a stable aqueous dispersion at a concentration of 1mg/1mL. The chitosan-conjugated nanoparticles showed thermo sensitive behaviors such as LCST and size shrinkage that were affected by the PNIPAAm core and induced some particle aggregation around LCST, which was not shown in the NIPAAm-co-AA nanoparticles. These chitosan-conjugated nanoparticles are also expected to be more biocompatible than the PNIPAAm core itself through the chitosan shell structures.

PVA 하이드로겔의 내열특성에 방사선 가교와 열처리가 미치는 효과 (Effect of the Radiation Crosslinking and Heating on the Heat Resistance of Polyvinyl Alcohol Hydrogels)

  • 박경란;노영창
    • 공업화학
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    • 제16권3호
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    • pp.354-360
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    • 2005
  • 본 연구에서는, 방사선 가교와 열처리에 의해 내열특성을 가진 polyvinyl alcohol (PVA) 수화겔을 제조하였다. 제조된 수화겔의 겔화율, 팽윤도와 겔강도 같은 기계적 특성을 측정하였다. DSC와 XRD를 이용하여 구조적 변화를 알아보았다. 수화겔의 겔화율과 겔강도는 방사선 조사 후에 열처리 과정을 했을 경우에 방사선 조사만 했을 때보다 높은 값을 보였다. 또한, 방사선 조사한 수화겔과 방사선 조사 후에 열처리 과정을 한 수화겔이 고온에서의 내열특성이 우수하였다.

환원된 산화그래핀/젤라틴 복합필름의 합성과 분석 (Synthesis and Characterization of Reduced Graphene Oxide/Gelatin Composite Films)

  • Chen, Guangxin;Qiao, Congde;Xu, Jing;Yao, Jinshui
    • 폴리머
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    • 제38권4호
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    • pp.484-490
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    • 2014
  • Reduced graphene oxide (RGO) was fabricated using gelatin as a reductant, and it could be stably dispersed in gelatin solution without aggregation. A series of RGO/gelatin composite films with various RGO contents were prepared by a solution-casting method. The structure and thermal properties of the RGO/gelatin composite films were characterized by UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). The addition of RGO enhances the degree of crosslinking of gelatin films and decreases the swelling ability of the gelatin films in water, indicating that RGO/gelatin composite films have a better wet stability than gelatin films. The glass transition temperature ($T_g$) of gelatin films is also increased with the incorporation of RGO. The presence of RGO slightly increases the degradation temperature of gelatin films due to the very low content of RGO in the composite films. Since gelatin is a natural and nontoxic biomacromolecule, the RGO/gelatin composite films are expected to have potential applications in the biomedical field.

에폭시/PMR-15 폴리이미드 블렌드계의 경화동력학 및 열안정성에 관한 연구 (Studies on Cure Behavior and Thermal Stability of Epoxy/PMR-15 Polyimide Blend System)

  • Lee, Jae-Rock;Lee, Hwa-Young;Park, Soo-Jin
    • 한국복합재료학회:학술대회논문집
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    • 한국복합재료학회 2002년도 추계학술발표대회 논문집
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    • pp.265-268
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    • 2002
  • In this work, the blend system of epoxy and PMR-15 polyimide is investigated in terms of the cure behaviors and thermal stabilities. The cure behaviors are studied in DSC measurements and thermal stabilities are also carried out by TGA analysis. DDM (4, 4'-diamino diphenyl methane) is used as curing agent for EP and the content of PMR-15 is varied within 0, 5, 10, 35, and 20 phr to neat EP. As a result, the cure activation energy ($E_a$) is increased at 10 phr of PMR-15, compared with that of neat EP. From the TGA results of EP/PMR-15 blend system, the thermal stabilities based in the initial decomposed temperature (IDT) and integral procedural decomposition temperature (IPDT) are increased with increasing the PMR-15 content. The fracture toughness, measured in the context of critical stress intensity factor ($K_{IC}$) and critical strain energy release rate ($G_{IC}$), shows a similar behavior with $E_a$. This result is probably due to the crosslinking developed by the interactions between intermolecules in the polymer chains.

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