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Property modulation of poly(N-isopropylacrylamide) hydrogels by incorporation of modified silica
Ham, Myong Jo,Kim, Young Ho Wiley Subscription Services, Inc., A Wiley Company 2008 Polymer engineering and science Vol.48 No.12
<P>Poly(N-isopropylacrylamide) (PNIPA)/silica composite hydrogels were prepared and the effects of the silica incorporation on the swelling and breaking characteristics of the hydrogels were investigated. To improve the dispersive property of silica in the PNIPA matrix via the formation of covalent bonds between the polymer and silica, vinyl groups were introduced in the silica by reacting it with a coupling agent, 3-methacryloxypropyltrimethoxysilane. When unmodified silica was used as filler in the PNIPA-composite hydrogel, the swelling ratio of the composite hydrogel below the critical gel transition temperature (CGTT) increased with increasing silica content. However, when the modified silica was used as the filler, the swelling ratio below CGTT decreased with increasing silica content because of the enhanced distribution and additional crosslinking. Above CGTT, the swelling ratios of the PNIPA/silica hydrogels were similar regardless of the silica modification. The gel breaking stress of the hydrogels increased with increasing silica content, and this enhancement was larger for the modified silica hydrogel. Scanning electron microscopy images showed that the modified silica particles were distributed more evenly in the PNIPA matrix than the unmodified ones were and that the size of cell-like structure of the hydrogel decreased with increasing modified silica content. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers</P>
씀바귀(Ixeris dentata Nakai) 생즙 추출물의 생리활성
김명조(Myong-Jo Kim),김주성(Ju-Sung Kim),조미애(Mi-Ae Cho),강원희(Won-Hee Kang),정동명(Dong-Myong Jeong),함승시(Seung-Shi Ham) 한국식품영양과학회 2002 한국식품영양과학회지 Vol.31 No.5
생식용 씀바귀의 섭취의 일환으로 생즙의 생리활성을 검색하기 위하여 본 실험을 실시하였다. DPPH free radical 소거법에 의한 항산화활성을 검정한 결과 에칠아세테이트 분획물이 RC_(50)값이 28 μg/mL로 강한 활성을 나타내었다. 항미생물 활성 실험에서는 곰팡이 균주에 대해서는 생즙 농축액이 분획물에 비하여 우수한 활성을 나타냈으며, 특히 Hypocrea nigricans에 대해서는 대조구보다 우수한 활성을 나타낸 반면 세균균주에 대해서는 에칠아세테이트 분획물이 우수한 활성을 나타내었다. 또한 각 균주에 대하여 씀바귀 생즙이 독성을 나타내지 않는 범위에서 직접 돌연변이원(MNNG, ANQO)과 간접돌연변이원(B(a)P, Trp-P-1)에 대하여 실험을 실시한 결과 강력한 발암물질로써 직접 변이원으로 사용된 MNNG(0.4 μg/plate)의 경우 S. typhimurium TA100 균주에서 시료농도 50 μg/plate에서 부탄올 분획물이 78.72%로 가장 높은 억제 효과가 나타냈으며, 4NQO(0.15 μg/plate)에 대한 S. typhymurium TA98 균주에서 에칠아세테이트 분획층이 74.21%로 가장 높은 억제 효과를 나타냈으며, TA100 균주의 경우에는 부탄올 분획물(75 μg/plate)에서 73.11%로 가장 높은 억제 효과를 나타내었다. Trp-P-1(0.15 μg/plate)을 사용한 S. typhimurium TA98 균주에서는 시료농도 100 μg/plate에서 물 분획물(75 μg/plate)에서 83.09%의 가장 높은 억제 효과를 보였고, TA100 균주의 경우, 시료농도 100 μg/plate에서 부탄올 분획물에서 68.88%의 가장 높은 억제 효과를 보였고, B(a)P(10 μg/plate)에서는 TA98 균주 100 μg/plate의 시료농도에서는 에칠아세테이트 분획물이 78.83%로 가장 높은 억제 효과를 보였으며, TA100 균주 100 μg/plate의 시료농도에서는 핵산 분획물이 75.96%로 가장 높은 억제 효과를 보였다. 각종 암세포주(A549, Hep3B, MCF-7)에 대한 증식 억제 효과를 실험을 한 결과, 폐암세포주인 A549세포에서는 부탄올 분획물(375 μg/mL)이 93.75%로 가장 높은 억제 효과를 나타내었고, 간암세포주인 Hep3B에서는 핵산 분획물(500 μg/mL)이 84.91%로 가장 높은 억제 효과를 보였다. 또한, 유방암 세포주인 MCF-7에서도 핵산 분획물(500 μg/mL)이 68.56%의 높은 억제 효과를 보였다. 씀바귀 추출물은 인간 정상 간세포 293에서 시료농도에 따른 증식 억제 효과를 보였다. 1000 μg/mL 시료 첨가 시 암세포에 대하여 대부분 60% 전후의 성장 억제를 하였고, 정상인 293세포에 대해서는 32% 이하로 생육을 억제하였다. 이는 씀바귀 추출물이 암세포의 성장억제 대한 높은 효과에 비해 정상세포에 대해서는 비교적 낮은 독성을 나타냄을 알 수 있었다. Ixeris dentata extracts exhibited antimicrobial activity against some bacteria and fungi. Also EtOH extracts showed strong antioxidant activity and RC_(50) value was 28 μg/mL. The inhibitory effect of Ixeris dentata on the mutagenicity in Salmonella and cytotoxicity on cancer cell were studied. Ixeris dentata extracts showed antimutagenic effects of 78.83 and 75.96% on B(a)P in S. typhimurium TA98 and TA100, respectively. These extracts showed 78.72% antimutagenicity on TA100 against MNNG. The Ixeris dentata extract with strong antimutagenic activities was further fractionated by hexane, ethyl acetate, butanol and water. Butanol fraction was found to be highest in antimutagenic activity against MNNG than the other fractions. Butanol fraction of Ixreis dentate revealed the highest cytotoxicity against A549 human lung carcinoma cells in which cell growth was inhibited by 93.75% at 375 μg/mL. Hexane fraction of Ixeris dentata exhibited 68.56% inhibition against MCF-7 human breast adenocarcinoma cells at 500 μg/mL. Hexane fraction of Ixeris dentata exhibited 84.91% inhibition against Hep 3B human hepatocellular carcinoma cells at 500 μg/mL. From these results, it is considered that Ixeris dentata has strong antimutagenic and anticancer effects in vitro. However, these extracts and fractions did not show any cytotoxic effect against 293 cells.
고온 열처리에 의한 Poly(phenylene sulfide) 필름의 특성 변화
함명조,김영호,Ham, Myong-Jo,Kim, Young-Ho 한국섬유공학회 2010 한국섬유공학회지 Vol.47 No.2
Amorphous poly(phenylene sulfide) (PPS) films were prepared by melt-pressing virgin PPS chips of high linearity and quenching into ice water. The films were annealed at $240^{\circ}C$ for up to 17 days and investigated by using a DSC. Both the melting temperature and heat of melting of PPS increased with increasing annealing time at $240^{\circ}C$, whereas the melt crystallization temperature and heat of melt crystallization decreased. Although the melting peak on heating still appeared, the melt crystallization peak on cooling disappeared after more than 10 days annealing, indicating the introduction of high degree of cross-linking. FTIR analysis and solubility tests of the annealed films also suggested the introduction of crosslinking. Increased crosslinking density refrained PPS from melt crystallization and dissolution in a solvent. Annealing at lower temperature such as $160^{\circ}C$ for up to 24 hours resulted in increasing the tensile strength of the films significantly without crosslinking. The chemical resistance of the films was almost unaffected in strong acid and alkaline solutions at $93^{\circ}C$ for 7 days.
포스파이트 화합물이 PTT/PET 용융 블렌드의 열적 특성에 미치는 영향
함명조,방경,김영호,Ham, Myong-Jo,Pang, Kyeong,Kim, Young-Ho 한국섬유공학회 2008 한국섬유공학회지 Vol.45 No.1
The effects of triphenyl phosphite (TPP) and bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite (BPDP) on the transesterification and thermal properties of poly(trimethylene terephthalate) (PTT) and poly(ethylene terephthalate) (PET) melt blends were investigated. PTT/PET melt blends containing small amount of TPP or BPDP were prepared by mixing them at $280^{\circ}C$ for different times using a twin screw type internal mixer, and their thermal properties were investigated by using a DSC. With addition of phosphite compounds, TPP or BPDP, during the melt blending, the trans esterification reaction was retarded and the melting point depression decreased. TPP was more effective than BPDP in decreasing the transesterification during the melt blending. NMR analysis showed that the randomness of PTT/PET blend containing 1% of TPP prepared at the same melt mixing conditions was much lower than the one without TPP, which confirmed the effectiveness of TPP in suppressing the transesterification reaction of the PTT/PET blends.
PPS/PET 및 PPS/PA66 블렌드에 대한 상용화제의 영향
배꽃하얀,함명조,김영호,Bae, Ggot-Ha-Yan,Ham, Myong-Jo,Kim, Young-Ho 한국섬유공학회 2012 한국섬유공학회지 Vol.49 No.1
Two commercial compatibilizers of ethylene glycidyl methacrylate (EGMA) and styrene-b-ethylene/butyleneb-styrene grafted with maleic anhydride (SEBS-g-MA) were added to poly(phenylene sulfide) (PPS)/poly(ethylene terephthalate) (PET) (80/20, weight ratio) and PPS/polyamide 66 (PA66) (80/20, weight ratio) mixture, respectively. This was done by using a twin screw extruder via a melt blending method and the blends of the three components were melt-pressed and quenched to the films of 200 ${\mu}m$. Changes in thermal, mechanical, chemical and morphological properties of the blend films were analyzed by using DSC, DMA, WAXS, SEM and UTM. DSC results showed that EGMA in PPS(80)/PET(20)/EGMA blends lowered $T_g$ of PPS. They hindered the crystallization of both PPS and PET. Addition of EGMA imparted partial miscibility to the immiscible PPS(80)/PET(20) blends but the total miscibility and compatibility were not enhanced. Mechanical and chemical properties of PPS80/PET20/EGMA blend films deteriorated more with an increase in EGMA content. SEBS-g-MA did not work as a compatibilizer at all for PPS(80)/PA66(20) blends rather it enduced phase separation of the blends.