• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.5
• /
• pp.430-434
• /
• 2001

We synthesized a new photo-crosslinkable polymer (polyimide (PI)-chalcone-biphenyl (BP)) and liquid crystal (LC) aligning capabilities for nematic (N) LC with obliquely polarized UV exposure on a photo-crosslinkable polymer were studied. The high pretilt angle in NLC was obtained by polarized UV exposure on a PI-Chal-BP surface for 3 min. The high pretilt angle generated in NLC is attributed to the biphenyl moieties and the photo-dimerized chalclone group of a photopolymer. Also, good thermal stability of a PI-Chal-BP were obtained by thermogravimetric analysis (TGA) measurement until 450$^{\circ}C$. Finally, good voltage-transmittance curves and response time were observed by UV exposure on a PI-Chal-BP surface for 3min.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.9
• /
• pp.770-775
• /
• 2000

A new photo-polymer material of the copoly (PM4Ch-ChMA), copoly (poly (4-methacryloyloxy)chalcone-cholesteryl methacrylate) for homeotropic alignment was synthesized and the electro-optical (EO) performance for the photo-aligned vertical-aligned (VA)-LC display (LCD) was studied. Good thermal stabilities of synthesized copolymer were obtained by TGA(Thermogravimetric Analysis) measurement. Good voltage-transmittance (V-T) and response time characteristics for the photo-aligned VA-LCD with polarized UV exposure in oblique direction($\theta$$_{i}$=30$^{\circ}$) on a copolymer-1 (2%) surfaces for 1 min were observed. but, light leakage in the off-state was observed. Therefore, we achieved excellent V-T and response time characteristics for the photo-aligned VA-LCD with UV exposure on a copolymer-3 (30%) surfaces for 3 min.n.

• Composites Research
• /
• v.33 no.1
• /
• pp.25-29
• /
• 2020

A liquid crystalline thermosetting-epoxy-based composite was fabricated using diglycidyl ether of 4,4'-biphenol, tin(IV) oxide as a filler, and sulfanilamide as a curing agent. To investigate the thermal behavior, Thermogravimetric Analysis and Laser Flash Apparatus were performed using 3.0-7.0 wt% Tin(IV) oxide. The result showed that the activation energy and thermal conductivity were proportional to the amount of added filler.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05b
• /
• pp.1127-1130
• /
• 2010

본 연구에서는 CNT의 분산성을 개선하고자 다중벽 탄소나노튜브(multi-walled carbon nanotube, MWNT)에 butyllithium solution 및 hexyllithium solution을 이용하여 표면을 화학적으로 개질하였다. 개질된 MWNT는 적외선 분광 분석 및 Raman spectrophotometer를 이용하여 MWNT에 작용기가 도입되었는지를 확인하였다. 또한, 열중량분석기(Thermogravimetric analysis, TGA)를 이용하여 작용기가 도입된 MWNT의 열적 성질을 측정하였으며, MWNT 및 개질된 MWNT를 다양한 용매에 따른 분산성을 확인하였다.

• Fibers and Polymers
• /
• v.3 no.3
• /
• pp.109-112
• /
• 2002

Polybutadiene(PB) was epoxidized to various extents with m-chloroperbenzoic acid (MCPBA) in homogeneous solution. The thermal properties of the epoxidized PBs were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). As a result of epoxidation the glass transition temperature (Tg) of PB increased by approximately $0.8^{\circ}$ for each 1 mol% of epoxidation. The thermal decomposition of the epoxidised PBs occurred in two-step process, while that of PB exhibited apparent one-step degradation process.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.55 no.7
• /
• pp.359-363
• /
• 2006

Single-walled carbon nanotubes (SWCNTs) with few defects and very small amount of amorphous carbon coating have been synthesized by catalytic decomposition of methane in $H_2$ over well-dispersed metal particles supported on MgO. The yield of SWCNTs was estimated to be 88.5% and the purities of SWCNTs thus obtained were more than 90%. Peak of the radial breathing mode in the Raman spectrum demonstrated that the diameters of synthesized CNTs are in the range 0.4-2.0 nm. Our results also indicated that MgO support materials are useful to a large-scale synthesis of high-quality SWCNTs. Increasing temperature could remarkably increase the yield and also improve the quality of SWCNTs from catalytic decomposition of methane. The morphologies and microstructures of the synthesized carbon materials were characterized by scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray diffraction (XRD).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.4
• /
• pp.336-340
• /
• 2001

We have investigated the generation of pretilt angle and alignment stability for a nematic liquid crystal (NLC) with obliquely polarized UV exposure on the three kinds of photo-polymer. High pretilt angle of the NLC was obtained by polarized UV exposure on a PM4Ch surface for 1 min. But, the low pretilt angle of he NLC on a PVCi surface was observed. The pretilt angle generated is attributed ot the photosensitivity by the long side chaining of photo-polymer. Also, a good thermal stability of the three kinds of photo-polymer were obtained by thermogravimetric analysis (TGA) measurement until 300$^{\circ}C$. Finally, the good LC aligning capabilities using the photodimerization method were observed by annealing-treatment until 150$^{\circ}C$.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.722-723
• /
• 2006

A new method has been developed to fabricate microcomponents by a combination of photolithography and sintering of metallic powder mixtures, without the need for compression and the addition of Mg. This involves (1) the fabrication of a micromould, (2) mould filling of the powder/binder mixture, (3) debinding and (3) sintering. The starting powdered materials consisted of a mixture of aluminium powder(average size of 2.5 um) and alloying elemental powder of Cu and Sn(less than 70nm), at appropriate proportions to achieve nominal compositions of Al-6wt%Cu, Al-6wt%Cu-3wt%Sn. This paper presents detailed investigation of debinding behaviour and microstructural development.

• Journal of Aerospace System Engineering
• /
• v.7 no.4
• /
• pp.36-41
• /
• 2013

In order to improve incombustibility of EPDM(Ethylene propylene diene monomer)-based rubber, inorganic materials as $Al(OH)_3$ and $Sb_2O_3$ were added. The mechanical and thermal properties have been measured for vulcanized rubber loaded with different concentrations of $Al(OH)_3$ and $Sb_2O_3$. As inorganic material contents increases from 5phr to 30phr, the specific gravity and hardness increase while elongation at break decreases. This study performed incombustibility test and thermal analysis through TGA(Thermogravimetric Analyzer). As a results, incombustible and thermal properties of EPDM-based rubber were improved as $Al(OH)_3$ and $Sb_2O_3$ contents increase.

• Journal of the Korean Society of Safety
• /
• v.18 no.4
• /
• pp.57-63
• /
• 2003

Thermal degradation of Acrylonitrile butadiene rubber(NBR), which is used for O-ring material as elastomeric sealed diaphragm value in the nuclear power plants, is examined. The thermal degradation is accelerated at 130$^{\circ}C$ by Arrhenius exploit method using the activation energy calculated by thermogravimetric analysis. The weight loss temperature and glass transition temperature are verified for thermally aged NBR. The relationship between dynamic mechanical properties and elongation at break are also investigated. The threshold alue of thermally aged NBR is a ten year in the change of elongation at break.