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Chain orientation and Degradation Behavior of Poly[(R)-3-hydroxybutyrate] Lamellar Crystals
이원기,조남주,하창식,Lee, Won Gi,Jo, Nam Ju,Ha, Chang Sik Korean Chemical Society 2001 Bulletin of the Korean Chemical Society Vol.22 No.8
Topological changes caused by the alkaline and enzymatic attacks of solution-grown, chain-folded lamellar crystals (SGCs) of poly[(R)-3-hydroxybutyrate] P(3HB) have been studied in order to investigate the chain-folding structure in P(3HB) crystal regions. NaOH and an extracellular PHB depolymerase purified from Alcaligenes faecalis T1 were used for alkaline and enzymatic hydrolysis, respectively. The measurements were performed on crystals attached to a substrate which is inactive to degradation mediums. Both alkaline and enzymatic attacks lead to a breakup of the lamellar crystals along the crystallographic b-axis during initial erosion. Since hydrolysis preferentially occurs in amorphous regions, this morphological result reflects relatively loosely packed chains in core parts of lamellar crystals. Additionally, it was supported by the ridge formation along the b-axis in the lamellar crystals after thermal treatment at a low temperature because of the thermally sensitive nature of the loosely packed chains in lamellar crystals. However, the alkaline hydrolysis accompanied the chain erosions or scissions in quasi-regular folded lamellar surfaces due to smaller size of alkaline ions in comparison to the enzyme, resulting in the decrease of molecular weight.
방오도료용 폴리우레탄 수지의 폴리올 종류에 따른 자기 마모 특성
김봉주(Bong-Ju Kim),박순민(Soon-Min Park),조남주(Nam-Ju Jo) 한국고분자학회 2017 폴리머 Vol.41 No.5
선박용 방오도료는 선박 표면의 부식과 선박 표면으로의 해양생물의 부착을 방지하는데, 해양 환경 오염 없이 방오성능이 우수한 방오도료 수지의 개발이 필요한 실정이다. 본 연구에서는 수용성 및 유성의 polyurethane(PU) 수지를 합성하고 방오제로써 4가 암모늄 염을 치환시킨 새로운 방오도료 수지를 개발하였다. 그리고 PU 수지의 폴리올로 에테르 계열의 poly(ethylene glycol)(PEG) (수평균 분자량 200과 600) 및 에스터 계열의 poly(tetramethylene adipate) glycol(PTAd) (수평균 분자량 600)을 사용하여, 해수 침지 하에서의 폴리올 종류에 따른 수용성 및 유성 PU 수지의 자기 마모 특성을 평가하였다. Antifouling paints have been used to prevent corrosion of the surface of the ship hulls (vessels) and the adhesion of marine organisms from these surfaces. And the development of a new type of antifouling paint resin which has excellent antifouling performance and no persistence in the marine ecology is necessary. In this study, we have studied polyurethane (PU) and waterborne polyurethane (WPU) resins which are considered to be applied as a new antifouling paint matrix. PU and WPU resins were synthesized by 4,4"-diphenylmethane diisocyanate (MDI), 2,2"-bis(hydroxymethyl) butyric acid (DMBA), 1,4-butanediol, polyethylene glycol (PEG) as ether type polyol and poly(tetramethylene adipate) glycol (PTAd) as ester type polyol. And then quaternary ammonium salts (QAS) which are effective biocides were substituted. After that, the synthesized PU and WPU resins were tested by the laser scan micrometer to confirm the self-polishing property with different types of polyol by measuring film thickness in sea water.
폴리우레탄과 개질된 질화붕소로 이루어진 난연성 방열 복합체
김민규 ( Min-gyu Kim ),이창록 ( Chang-rock Lee ),조남주 ( Nam-ju Jo ) 한국공업화학회 2020 공업화학 Vol.31 No.5
기존의 방열필름의 연소문제를 해결하기 위해 poly(tetra methylene glycol) (PTMG), 4,4’-methylenebis(phenyl isocyanate) (MDI)와 유기인이 도입된 실란 커플링제로 표면개질한 질화붕소를 사용하여 폴리우레탄과 개질된 질화붕소로 이루어진 복합체를 제작하였다. Fourier transform-infrared (FT-IR) 분광 분석을 통해 질화붕소의 개질과 복합체의 합성 여부를 확인하였다. 또 universal testing machine (UTM) 측정을 통해 개질된 질화붕소의 함량에 따른 복합체의 기계적 물성변화를 확인하였으며, layser flash analysis (LFA)와 UL94 측정을 통해 열적 특성을 조사하였다. 그 결과, 복합체의 열전도도가 1.19 W/m·K로 증가하였으며, 자기소화성이 없어 타기 쉬운 폴리우레탄의 난연성이 UL94 V-1 등급으로 향상되었다. Polyurethane/modified boron nitride (PU/m-BN) composite was synthesized from the poly(tetra methylene glycol) (PTMG), 4,4’-methylenebis(phenyl isocyanate) (MDI), and modified boron nitride (m-BN). The modification of boron nitride and synthesis of PU/m-BN composite were confirmed by Fourier transform infrared (FT-IR) spectroscopic analyses. The mechanical properties of the PU/m-BN composites were measured using the universal testing machine (UTM) and the thermal properties of the composites were investigated ser flash analysis (LFA) and UL94 measurements. As a result, the thermal conductivity of the polyurethane composite increased to 1.19 W/m·K, and the flame retardancy of the easy to burn polyurethane, which was not self-extinguishing was improved to UL94 V-1 grade.