• Title/Summary/Keyword: 가교화

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The Effect of Crosslinking on the Actuation of Electroactive IPMC Prepared with Fluoroalkyl Methacrylate/Acrylic Acid/HEMA Copolymer (Fluoroalkyl Methacrylate/Acrylic Acid/2-HEMA 공중합체로 제조한 IPMC의 구동 특성에 미치는 가교의 영향)

  • Jeong, Han-Mo;La, Young-Soo
    • Polymer(Korea)
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    • v.29 no.5
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    • pp.463-467
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    • 2005
  • In order to enhance the actuation force of ionic polymer-metal composite (IPMC) made with the acrylic copolymer of fluoroalkyl methacryate, acrylic acie, and 2-hydroxyethyl methacrylate(HEMA), the hydroxy group of HEMA was corsslinked with 1,3-diethoxy-1,1,3,3-tetramethyldisiloxane. The water uptake was reduced and the mechanical strengths and the actuation force of the membrane was improved by crosslinking. However, current and deformation responses of IPMC were decreased by crosslinking.

A Study on the Electron Beam Crosslinking of Acrylic Pressure Sensitive Adhesives for Polarizer Film (전자선 조사를 통한 편광필름용 아크릴계 고분자의 가교화 반응에 대한 연구)

  • Park, Jung-Jin;Choi, Hong-June;Ko, Hwan-Soon;Jeong, Eun-Hwan;Youk, Ji-Ho
    • Polymer(Korea)
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    • v.36 no.3
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    • pp.344-350
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    • 2012
  • New pressure sensitive adhesives (PSAs) for polarizer film were prepared by electron beam (e-beam) radiation to acrylic copolymers, and their adhesive properties were investigated. The acrylic copolymers were synthesized by free radical polymerization of $n$-butylacrylate (BA), 2-hydroxyethyl methacrylate (HEMA), and acrylic acid (AA). The acrylic copolymers were coated on PET release films to a thickness of 25 ${\mu}m$, laminated to polarizer films, and then radiated with e-beam at room temperature. Gel fractions of all the acrylic copolymers after e-beam radiation at 50 kGy were higher than 93%, and their crosslinking densities were increased with increasing the content of HEMA units. PSA prepared by e-beam radiation of acrylic copolymer synthesized with a feed ratio of BA/HEMA/AA = 89.5/10/0.5 (w/w/w) at a dose of 50 kGy exhibited the best adhesion performances in terms of peel strength, creep resistance, durability and reliability, and light leakage. It is expected that the preparation method of PSAs via e-beam irradiation will improve the producibility and workability of polarizer film for liquid crystal display.

Physiochemical Properties of Dual-Modified (Hydroxypropylated and Cross-linked) Rice Starches (하이드록시프로필화 후 가교화시킨 복합변성 쌀 전분의 이화학적 특성)

  • Choi, Hyun-Wook;Kim, Sang-Kab;Choi, Sung-Won;Kim, Chang-Nam;Yoo, Seung-Seok;Kim, Byung-Yong;Baik, Moo-Yeol
    • Food Engineering Progress
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    • v.15 no.4
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    • pp.332-337
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    • 2011
  • Physicochemical properties of hydroxypropylated and cross-linked (HPCL) rice starch were investigated. Dual modification of rice starch was carried out by hydroxypropylation using propylene oxide (2, 6, and 12%) and then crosslinking using phosphorus oxychloride (0.005% and 0.02%). Swelling power of dual-modified rice starch increased at lower temperature (60$^{\circ}C$) than that of native rice starch (70$^{\circ}C$). HPCL rice starch showed slightly lower solubility (1.6-6.1%) than native rice starch (2.2-13.8%). Solubility and swelling power tended to gradually increase with increasing phosphorus oxychloride contents. RVA pasting temperature (66.2-70.8$^{\circ}C$) and peak viscosity (160.6- 171.1 RVU) of HPCL rice starch were lower than that of those of native starch (71.3$^{\circ}C$, 190.4 RVU) and decreased with increasing propylene oxide concentration. DSC thermal transitions of HPCL rice starches shifted to lower temperature and show less amylopectin melting enthalpy (11.8-9.8 J/g) than that of native rice starch (11.9 J/g). Overall, physicohemical properties of HPCL rice starches were highly dependent on hydroxypropylation rather than crosslinking.

Separation and Purification of Chiral Compounds Using Crosslinked Sodium Alginate Membranes (가교화된 알진산나트륨막을 이용한 키랄 화합물 분리 정제)

  • 김지혜;김상균;이규호;제갈종건
    • Polymer(Korea)
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    • v.28 no.4
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    • pp.352-359
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    • 2004
  • Membrane technology was used for the optical resolution of the various racemic compounds such as tryptophan, tyrosine and phenylalanine, using enantioselective membranes prepared from sodium alginate (SA) and glutaraldehyde as a membrane material and crosslinking agent, respectively, The chemical structure of the membranes was characterized with FT-IR spectrophotometry and 3D molecular structure modeling study was done to figure out the optical resolution mechanism through the membrane. Effects of degree of crosslinking, feed concentration, operating pressure and different kinds of feed solution on the membrane performances were studied. As results, it was found that with increasing degree of crosslinking and membrane thickness, and decrease in the concentration of the feed solution and smaller size of solutes, the enantinselectivity of the membrane was improved. When the sodium alginate membranes with 80% of swelling index and 79${\mu}{\textrm}{m}$ of thickness were used, 77% of enantiomeric excess was obtained.

A Study on Physical Properties of EPDM/Polyhedral Oligomeric Silsesquioxane (POSS) Composites (EPDM/POSS(Polyhedral oligomeric silsesquioxane) 복합재료의 물성 연구)

  • Park, Hyun-Ho
    • Applied Chemistry for Engineering
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    • v.32 no.4
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    • pp.472-477
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    • 2021
  • The crosslinking behavior of polyhedral oligomeric silsesquioxane (POSS) containing eight acrylate groups in a cage form in ethylene-propylene-diene rubber (EPDM) peroxide crosslinking, the effect on mechanical properties, and the thermal stability were investigated. An EPDM/POSS composite material was prepared by mixing 0 to 12 parts per hundreds of rubber (phr) of POSS per 100 phr of rubber by content and adding a peroxide crosslinking agent. As a result of crosslinking properties, it was found that the acrylate group of POSS was activated by peroxide and improved the peroxide crosslinking efficiency. Although the dispersion stability of POSS in EPDM/POSS composites was poor, the fracture strength, elongation and thermal stability were improved.

Magnetorheological Elastomer Based on Reactive Blend of Maleic Anhydride Grafted Chloroprene Rubber and Epoxidized Natural Rubber (말레무수물로 개질된 클로로프렌 고무와 에폭시화 천연고무의 반응 블렌드에 기초한 자기유변 탄성체)

  • Choi, Jinyoung;Chung, Kyungho
    • Elastomers and Composites
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    • v.49 no.4
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    • pp.267-274
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    • 2014
  • Self vulcanizable blend system for magnetorheological elastomer (MRE) has been studied by dispersing magneto responsible particle (MRP) on elastomeric matrix. Chloroprene rubber was modified with maleic anhydride (MAH) using heat and pressure which is called dynamic maleation process. The optimum graft ratio of MAH was found at 10 phr contents and reaction temperature of $100^{\circ}C$. This could be confirmed by FT-IR analysis. Epoxided natural rubber (ENR) was blended with modified CR-g-MAH for self vulcanization. The optimum amounts of ENR was 30 wt% in terms of scorch time and curing rate. MRE was manufactured by electromagnetic equipment and orientation of MRE was confirmed by SEM. Finally, it was found that the tensile strength of anisotropic-MRE was higher than that of isotropic-MRE and the hardness was reverse.

Chitosan을 이용한 수종약물의 서방화에 관한 연구

  • 서성훈;김길수;김동현;박경옥;장미경;김태호
    • Proceedings of the Korean Society of Applied Pharmacology
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    • 1993.04a
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    • pp.104-104
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    • 1993
  • 시방성 제제에 대한 연구는 주로 제제학적 수단에 의한 약효의 지속화로서 제제설계상 제형개발 및 투여제형에서의 약물방출 조절로 체내의 유효 혈중농도를 유지한다. 이에 약물 방출 조절용 물질의 하나로서 체내 분해가 가능하고 독성이 없는 생체 고분자인 Chitosan이 약물방출 담체로서 양호함에 착안하여 약물의 서방화를 기하고자 본 실험에 착수 하였다. 모델 약물로서는 sulfamethoxazole, acetaminophen, sylimarin을 사용하여 chitosan gel 과 혼합비를 달리하여 고형 문산체를 조제하고 이것을 formaldehyde, glutaraldehyde, 1acetaldehyde, butylaldehyde 4종의 aldehyde를 사용하여 농도에 따른 가교화가 in vitro에서의 약물용출에 미치는 영향을 검토하였으며, 또한 위장을 거쳐 소화효소 또는 장내미생물 효소에 의한 chitosan 분해로 약물 방출의 촉진을 실험한바 지견을 얻었기에 보고한다.

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Preparation of Humidity Sensor Using Novel Photocurable Sulfonated Polyimide Polyelectrolyte and their Properties (광가교성 Sulfonated Polyimide 전해질 고분자를 이용한 습도센서의 제조 및 특성 분석)

  • Lim, Dong-In;Gong, Myoung-Seon
    • Polymer(Korea)
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    • v.36 no.4
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    • pp.486-493
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    • 2012
  • Photocurable sulfonated polyimide (SPI) polyelectrolyte containing chalcone group was prepared and fabricated on an alumina electrode pretreated with chalcone-containing silane-coupling agent. SPI films with bis(tetramethyl)ammonium 2,2'-benzidinedisulfonate ($Me_4N$-BDS)/4,4'-diaminochalcone (DAC)/pyromellitic dianhydride (PA)= 90/10/100 possessed very linear response(Y = -0.04528X+7.69446, $R^2=0.99675$) and showed resistance changing from 4.48 to $2.1k{\Omega}$ between 20 and 95 %RH. The response time for absorption and desorption measurements between 33 and 94 %RH% was about 79 s, which affirmed the high efficiency of crosslinked SPI film for rapid detection of humidity. A negative temperature coefficient showing $-0.49%RH/^{\circ}C$ was found and proper temperature compensation should be considered in future applications. Moreover, pretreatment of the substrates with chalcone-containing silane-coupling agent was performed to improve the water durability and the stability of the humidity sensors at a high humidity and a high temperature and long-term stability for 480 h. The crosslinked SPI films anchored to electrode substrate could be a promising material for the fabrication of efficient humidity sensors with superior characteristics compared to the commercially available sensors.