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PP/MMT 나노복합재료의 열안정성 및 기계적 계면 특성에 관한 연구
박수진,전병렬,송시용,이종문 한국공업화학회 2004 공업화학 Vol.15 No.1
본 연구에서는 몬모릴로나이트(Na^(-)-montmorillonite, MMT)를 dodecylammonium chloide로 유기적 개질하여 폴리프로필렌(PP) 나노복합재료의 열안정성과 기계적 계면 물성에 미치는 영향을 조사하였다. 나노복합재료의 구조 및 표면 특성은 각각 XRD와 FT-IR을 통해 알아보았고, 열안정성은 TGA를 통해 알아보았으며, 주조된 시편의 기계적 계면 물성은 K_(IC)와 G_(IC)를 통해 알아보았다. 실험 결과, dodecylammonium chloide을 이용한 MMT의 유기적 개질(DA-MMT)은 약 7.3 Å의 실리케이트 층간을 증가시켰고, DA-MMT 내의 CH_(2) 기에 의해 2800~2900 ㎝^(-1)에서 새로운 피크가 나타났다. PP/DA-MMT 나노복합재료의 열안정성은 순수한 PP 수지에 비해 향상되었는데, 이는 DA-MMT 입자와 PP 사이의 분자간 상호작용에 의한 것으로 판단된다. 또한, PP/DA-MMT 나노복합재료가 높은 기계적 계면 물성을 나타냈는데, 이러한 결과는 층간이 증가된 실리케이트에 PP가 쉽게 삽입되기 때문으로 판단된다. In this work. the effect of organic modification of Na-montmorillonite (MMT) with dodecylammonium chloride on thermal stabilities and mechanical interfacial properties of PP nanocomposites was investigated. The structure and surface properties of the nanocomposites were determined by XRD and FT-IR, respectively. The thermal stabilities of the nanocomposites were studied using a TGA analysis. Also, the mechanical interfacial properties were confirmed by KIC and GIC of casting specimens. As a result, the organic modification of MMT by dodecylammonium chloride(DA-MMT) led to the increase of the silicate layers to about 7.3 A, and the new peaks at 2800∼2900 cm^(-1) hand were shown in the presence of the CH groups on the DA-MMT. The thermal stahilities of PP/DA-MMT nanocomposites were higher than that of pure PP resin, which can be attributed to the increase of intermolecular interaction between DA-MMT particles and PP matrix. Also, the PP/DA-MMT nanocomposites had higher mechanical interfacial properties than those of pristime nanocomposites. These results explained that the pp was easily inserted in the spacing of the silcate interlayers of which were increased.
A Study on Electrical and Thermal Properties of Polyimide/MWNT Nanocomposites
박수진,Sung-Won Chae,John-Moon Rhee,강신재 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.8
In this work, the electrical and thermal properties of polyimide/multi-walled carbon nanotube (MWNT) nanocomposites were investigated. The polyimide/MWNT nanocomposites contained from 0 to 2.0 wt % of MWNT. The electrical properties of the polyimide films were characterized by a specific resistance measurement. The thermal properties were evaluated using thermogravimetric analysis (TGA) and a differential scanning calorimeter (DSC). It was found that the thermal properties of the polyimide nanocomposites increased with increasing MWNT content and specific resistance as well. This result indicated that the crosslinking of polyimide/MWNT nanocomposites was enhanced by good distribution of the MWNT in the polyimide resins, resulting in the increase of the electrical and thermal properties of the nanocomposites.
Local Drug Delivery System Using Biodegradable Polymers
Khang, Gil-Son,Rhee, John M.,Jeong, Je-Kyo,Lee, Jeong-Sik,Kim, Moon-Suk,Cho, Sun-Hang,Lee, Hai-Bang The Polymer Society of Korea 2003 Macromolecular Research Vol.11 No.4
For last five years, we are developing the novel local drug delivery devices using biodegradable polymers, especially polylactide (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) due to its relatively good biocompatibility, easily controlled biodegradability, good processability and only FDA approved synthetic degradable polymers. The relationship between various kinds of drug [water soluble small molecule drugs: gentamicin sulfate (GS), fentanyl citrate (FC), BCNU, azidothymidine (AZT), pamidronate (ADP), $1,25(OH)_2$ vitamin $D_3$, water insoluble small molecule drugs: fentanyl, ipriflavone (IP) and nifedipine, and water soluble large peptide molecule drug: nerve growth factor (NGF), and Japanese encephalitis virus (JEV)], different types of geometrical devices [microspheres (MSs), microcapsule, nanoparticle, wafers, pellet, beads, multiple-layered beads, implants, fiber, scaffolds, and films], and pharmacological activity are proposed and discussed for the application of pharmaceutics and tissue engineering. Also, local drug delivery devices proposed in this work are introduced in view of preparation method, drug release behavior, biocompatibility, pharmacological effect, and animal studies. In conclusion, we can control the drug release profiles varying with the preparation, formulation and geometrical parameters. Moreover, any types of drug were successfully applicable to achieve linear sustained release from short period ($1{\sim}3$ days) to long period (over 2 months). It is very important to design a suitable formulation for the wanting period of bioactive molecules loaded in biodegradable polymers for the local delivery of drug. The drug release is affected by many factors such as hydrophilicity of drug, electric charge of drug, drug loading amount, polymer molecular weight, the monomer composition, the size of implants, the applied fabrication techniques, and so on. It is well known that the commercialization of new drug needs a lot of cost of money (average: over 10 million US dollar per one drug) and time (average: above 9 years) whereas the development of DDS and high effective generic drug might be need relatively low investment with a short time period. Also, one core technology of DDS can be applicable to many drugs for the market needs. From these reasons, the DDS research on potent generic drugs might be suitable for less risk and high return.
The Effect of Molecular Weight of Drugs on Transdermal Delivery System Using Microneedle Device
Lee, Chang Rae,Kim, Moon Suk,Lee, Hai Bang,Lee, Han Ku,Rhee, John M.,Khang, Gil Son Trans Tech Publications, Ltd. 2007 Key Engineering Materials Vol.342 No.-
<P>We developed the successive roller type of microneedle system without pain to improve the permeation of drug through the skin barrier. The permeation rates of FITC-ovalbumin (OVA, MW: 45,000g/mole), FITC-insulin (MW: 5,733 g/mole) and FITC-bufexamac (MW: 227.37 g/mole) as model drugs were determined by modified Franz diffusion cells using the microneedle device with four times treatment. The average penetration fluxes of FITC- OVA, FITC-insulin and FITC-bufexamac were steeply increased from 13.4 to 83.3, 10.1 to 110.6 and 11.9 to 242.6 pmol/cm2 with treatment for 12 hrs, respectively. The lower the molecular weight of the drugs, the more the permeation flux investigated. In conclusion, we confirmed the possibility of the application for transdermal delivery of the larger molecular drugs as protein using the designed microneedle treatment device.</P>