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초음파화학법으로 합성한 광촉매 산화아연 나노입자와 PCM 마이크로캡슐을 복합한 잠수복용 고무 시트의 보온성 및 항균성
채하늘,이승한,민병길 한국섬유공학회 2023 한국섬유공학회지 Vol.60 No.3
Photocatalytic ZnO nanoparticles were synthesized through sonochemical synthesisprocess for depositing them onto PCM microcapsules for the purpose to providewarming ability and antibacterial activity to rubber sheets for diving suit. Spherical ZnOnanoparticles having average diameter of 50 nm could be synthesized in deionized waterunder ultrasonic irradiation for 30 min at pH 11.5. However, needle-like ZnO nanoparticleswere obtained in ammonium hydroxide instead of deionized water as medium. It wasfound that spherical shape is more favorable for the sonochemical coating thereof ontoPCM microcapsules. The formation of ZnO nanopartcles through Zn(OH)2 microparticleswere confirmed using UV-Vis spectroscopy and X-ray diffractometry. Composite rubbersheets containing 0-25 wt% of PCM microcapsules with or without ZnO nanoparicles wereprepared by solution casting. The composite rubber sheets exhibited much better warmingability compared than neat rubber sheet in cold water due to exothermic heat by PCMmicrocapsules. Moreover, The composite rubber sheets with ZnO nanoparicles showedexcellent antibacterial activity against bacteria of S. aureus by showing 99.9 % reduction ofbacteria.
상전이물질 마이크로캡슐의 표면에 초음파화학 코팅법으로 항균성 구리 나노입자의 도입
이지헌,채하늘,민병길 한국섬유공학회 2022 한국섬유공학회지 Vol.59 No.1
In this study, phase change material (PCM) microcapsules were prepared, andcopper nanoparticles were coated on the microcapsule surface through the sonochemicalcoating process for temperature regulation and antibacterial activities. n-octadecane andmelamine–formaldehyde resin were used as the PCM core and wall materials of microcapsules,respectively. It was observed that applying high-speed stirring above 7,000 rpm wascritical to form n-octadecane droplets in O/W emulsion with 3.5±0.5 μm in diameter usinga homogenizer. Spherical PCM microcapsules with 6.0±2 μm in diameter could beobtained at lower than pH 6. Copper nanoparticles could be successfully embedded onthe surface of PCM microcapsules through the sonochemical coating process. The PCMmicrocapsules coated with copper nanoparticles exhibited excellent antibacterial activitiesagainst S. aureus and K. pneumonia.
초음파화학 공정에 의한 파라핀계 상전이물질의 에멀전 형성과 이로 부터 멜라민-포름알데히드 수지를 벽 재료로 사용한 마이크로캡슐의 제조
한창훈,채하늘,민병길,Han, Chang-Hoon,Chae, Haneul,Min, Byung Gil 한국섬유공학회 2021 한국섬유공학회지 Vol.58 No.4
An O/W emulsion of paraffinic phase change material (PCM) was prepared through a sonochemical process for microencapsulation using melamine-formaldehyde resin as the wall material. It was found that the octadecane micelles selected as PCM were successfully formed in water with a diameter of 1-3 ㎛ through ultrasonication for 5 min. Anionic surfactants were found to be more effective than non-ionic surfactants in the formation of emulsions consisting of PCM micelles through a sonochemical process. Spherical PCM microcapsules were obtained from the PCM emulsion and melamine-formaldehyde prepolymer, which was used as the wall material. The diameter of the PCM microcapsules increased with increasing microencapsulation time and the prepolymer to PCM weight ratio.
알긴산 매트릭스에 동시형태고정화된 상전이물질 옥타데칸의분산상 크기가 용융잠열에 미치는 영향
이승한,채하늘,민병길 한국고분자학회 2022 폴리머 Vol.46 No.4
용융잠열이 매우 큰 상전이물질인 옥타데칸을 O/W 에멀젼 형성 공정을 통하여 알긴산 수지에 동시형태고정화시키는 연구를 수행하였다. 에멀젼 공정을 통하여 옥타데칸 마이셀의 크기를 10 μm 이하로 조절하는 것이 가능하였으며, 초음파 처리법이 고속교반법에 비하여 옥타데칸 마이셀의 크기가 훨씬 작게 조절되는 결과를 얻었다. 에멀젼의 옥타데칸 마이셀의 크기는 알긴산 수지를 용해시킨 하이브리드 용액에서도 동일한 크기의 분산상으로 유지되는 것으로 나타났다. 하이브리드 복합액을 필름 캐스팅하고 염화칼슘 수용액에서 응고 및 불용화시켜 복합필름을제조할 수 있었다. 복합필름의 용융잠열이 순수 알긴산의 용융잠열에 비하여 30-60%로 낮게 나타났는데, 용융잠열은 형태고정화된 옥타데칸 분산상의 크기에 비례한다는 결과를 얻었다. 이는 옥타데칸 분산상의 크기가 작을수록비표면적이 커지게 되어 표면에 존재하는 분자의 비율이 높아짐에 따라 결정화도가 낮아지고 결정의 완전성도 저하됨에 기인하는 것으로 결론지을 수 있었다.
알긴산/PVA 블렌드에 동시형태고정화된 상전이물질 옥타데칸의 형상변화 및 계면 형태가 용융잠열에 미치는 영향
이승한,채하늘,신창민,홍성민,민병길 한국고분자학회 2023 폴리머 Vol.47 No.1
수용성 고분자인 알긴산/poly(vinyl alcohol)(PVA) 블렌드 수용액에 상전이물질인 옥타데칸이 동시형태고정화된 복합필름을 제조하여 옥타데칸의 상분리 형상과 계면 특성이 잠열효율에 미치는 영향을 분석하였다. 고분자의농도를 4-18 wt%까지 조절하면서 옥타데칸을 동시형태고정화 시켰을 때, 낮은 농도에서는 디스크 형상으로 형태고정화 되었으나 고분자 농도가 증가함에 따라 종횡비가 낮아지면서 구형에 가까운 형상으로 형태고정됨을 알 수 있었다. 종횡비가 낮아질수록 계면의 비표면적이 작아지고 이에 따라 결정화에 방해를 받는 계면에 존재하는 옥타데칸의 비율이 낮아짐으로써 잠열효율이 증가하는 결과를 나타내었다. 또한 알긴산/PVA를 가교반응으로 개질하였을경우 동일조건에서 옥타데칸의 잠열효율이 낮아지는 것으로 나타났는데, 이는 가교에 따라 계면에 미세 요철이 발달되어 결과적으로 옥타데칸의 결정화가 방해된 것에 기인한 것으로 판단된다.
이승한,채하늘,김남윤,민병길 한국섬유공학회 2022 Fibers and polymers Vol.23 No.9
A novel in situ shape-stabilization process of paraffinic phase change material (PCM) in alginate matrix wasinvestigated for the purpose of temperature regulating application. n-Octadecane was selected as a paraffinic PCM because ofits adequate thermal transition temperature for applying to human body. As the size control of n-octadecane in polymermatrix less than 10 μm is a core factor for textile application, oil-in-water (O/W) emulsion of n-octadecane in water wereadopted for the size control in shape-stabilization of PCM (SSPCM) in polymer matrix. The micelle size of the PCMemulsion could be controlled in the range of 3-8 μm through O/W emulsion process with high-speed stirring at 3,000-7,000 rpm and small amount of surfactant. The size of micelles in the emulsion decreased with increasing of homogenizingspeed and the amount of surfactant. It was also confirmed that the PCM micelle size was maintained in alginate-PCM hybridsolution that was prepared by mixing the O/W emulsion and aqueous sodium alginate solution. The SSPCM films containing10-30 wt% of n-octadecane in alginate could be successfully prepared by casting the hybrid solution followed by coagulatingthe cast film in aq. CaCl2 resulting solidification and insolubilization of alginate through intermolecular ionic crosslinking byCa2+. It was interesting that the shape of n-octadecane in alginate matrix was not spherical but disk shape parallel to the filmsurface. It was presumed that the discus-type shape-stabilized form of n-octadecane in alginate matrix was originated byvertical compressive force applied during rapid coagulation of the hybrid solution having very low concentration of sodiumalginate (4 wt%). The shape of paraffinic PCM stabilized in polymer matrix through O/W emulsion is expected to becontrolled when the other polymeric system with thick concentration.