• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.7
• /
• pp.625-629
• /
• 2000

We synthesized a new copoly (PM4Ch-ChMA) copoly(poly(4-methacryloyloxy) chalcone-cholesteryl methacrylate) having chalconyl and cholesteryl moiety for homeotropic liquid crystal(LC) alignment. Pretilt angles of nematic(N) LC generated by linearly polarized UV exposure on the copolymer surfaces were investigated. Good thermal stabilities of the synthesized copolymer were obtained by TGA (Thermogravimetric Analysis) measurement. Pretilt angles of the NLC decreased with increasing UV exposure time on the copolymer surfaces. We consider that the pretilt angle of the NLC is attributed to increased chalcone by increased UV exposure time. High pretilt angle of the NLC is attributed to increased chalcone by increased UV exposure time. High pretilt angle of 81$^{\circ}$was observed after the UV exposure for 3 min.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2000.11a
• /
• pp.137-140
• /
• 2000

Synthesis of a new copoly (M4Ch-ChMA), copoly ((4-methacryloyloxy) chalcone-cholestery methacrylate), with chalconyl and cholesteryl moiety characteristics for photoalignment materials was investigated. Good thermal stabilities of the synthesized copolymers are confirmed by thermogravimetric analysis (TGA) measurement. The pretilt angles of the nematic liquid crystal (NLC) are reduced as UV exposure time is increased on the copolymer surfaces. A pretilt angle of 81$^{\circ}$ in NLC was observed with UV exposure of 3 min on the copolymer-3 surface. The NLCs pretilt angle is attributable to increased chalcone with increasing the UV exposure time.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.220-221
• /
• 2007

Recently, imprint lithography have received significant attention due to an alternative technology for photolithography on high performance microelectronic devices. In this work, we investigated thermal stabilities and dynamic mechanical properties of dielectric materials for thermal imprint lithography. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various curing agent and spherical filler were studied using dynamic differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rheometer and universal test machine(UTM).

• Macromolecular Research
• /
• v.17 no.8
• /
• pp.609-615
• /
• 2009

Two types of nano composite were obtained by in situ chemical method in polyaniline (PANI)/dodecyl-benzenesulfonic acid (DBSA) system depending on the use of either ammonium persulfate (APS) or ferric chloride ($FeCl_3$) as the oxidant. In order to study the difference of the two composites in the surface characteristics, thermal stability, and electric properties, the composite films were studied by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and temperature dependent DC electrical conductivity. The results revealed a large difference in the surface morphology, thermal stability, and the microstructure properties between the two composites, and these differences were considered responsible for the molecular order and conductivity.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.12
• /
• pp.1421-1427
• /
• 1999

4-Hydroxy-4'-methoxyazobenzene and 4-hydroxy-4'-cyanoazobenzene were synthesized from phenol with p-anisidine and p-aminobenzonitrile through a diazotization reaction, respectively. They were reacted with 2-chloroethanol, 2-(2-chloroethoxy)ethanol, or 2-[2-(2-chloroethoxy)ethoxy]ethanol to produce six kinds of new mesogenic alcohols having an azobenzene group that is sensitive to the ultraviolet. Twelve kinds of new photoresponsive monomers with two symmetrical mesogens were prepared by the reaction of the mesogenic alcohols with fumaric acid or maleic acid through a Mitsunobu reaction. The resulting monomers have different length of flexible ethyleneoxy spacer tethered to azobenzene group. The length of the spacer affected their thermal stability, solubility, and phase transition temperature. Structures of the monomers were identified by FT-IR and ¹H-NMR spectra. Their phase transition temperatures and thermal stability were also investigated by a differential scanning calorimetry (DSC) and a thermogravimetric analysis (TGA). From an optical polarizing microscopy, all the prepared monomers except fumarate-1 and maleate-1 were found to show enantiotropic liquid crystallinity with a smectic texture like focal-conic, fan-shaped, and batonnet textures.

• Polymer(Korea)
• /
• v.34 no.4
• /
• pp.306-312
• /
• 2010

Triphenylvinylsilane (TPVS) containing vinyl acetate (VAc), butyl acrylate (BA), and Nmethylolacrylamide (NMA) copolymers were prepared by emulsion polymerization. The polymerization was performed at $80^{\circ}C$ in the presence of auxiliary agents and ammonium peroxodisulfate (APS) as the initiator. Sodium dodecyl sulphate (SDS) and Arkupal N-300 were used as anionic and nonionic emulsifiers, respectively. The resulting copolymers were characterized by using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and dynamic light scattering (DLS). Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The morphology of copolymers was also investigated by scanning electron microscopy (SEM) and then the effects of silicone concentrations on the properties of the TPVS-containing VAc-acrylic emulsion copolymers were discussed. The obtained copolymers have high solid content (50%) and can be used in weather resistant emulsion paints as a binder.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.24 no.3
• /
• pp.149-157
• /
• 2018

Low density polyethylene (LDPE) has been researched in many industrial applications, and LDPE/zeolite 4A composites has been extensively studied for many applications such as microporous, breathable film and so on. LDPE/zeolite composite have a great potential for carbon dioxide adsorption film due to its high adsorption ability. In this study, LDPE/zeolite 4A composites with various contents were prepared by melt mixing process, and co-extrusion process was applied to develop a $CO_2$ adsorption conventional film and foamed film. The thermal, rheological, mechanical, physical and morphological properties of composite films has been characterized, and $CO_2$ adsorption of the composite films evaluated by thermogravimetric analysis (TGA) and the performance was found to be about 18 cc/g at 30.9 wt% of the zeolite content.

• Analytical Science and Technology
• /
• v.19 no.6
• /
• pp.504-511
• /
• 2006

Polysilanes with organic substituents such as methyl and phenyl were synthesized by Wurtz dechlorination-condensation reactions using ultrasonic from organochlorosilanes. The yields were compared with the results of thermal dechlorination-condensation reactions. Properties such as thermogravimetric analysis and photoreactivity were investigated for the possibility of applications.

• Polymer(Korea)
• /
• v.26 no.3
• /
• pp.400-409
• /
• 2002

Polyurethane microcapsules containing functional oil (citronella oil) were successfully prepared by conventional interfacial polymerization of tolulene 2,4-diisocyanate (TDI) and ethylene glycol (EG) and characterized by Fourier transform (FT-IR) spectroscopy, Ultraviolet spectroscopy, particle size analysis, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Tile effects of polymerization variables, such as surfactant concentration and agitation speed, on the particle size and particle size distribution were investigated. FT-IR spectroscopic data showed that citronella oil was successfully encapsulated in the microcapsule. Thermogravimetric analysis data showed that the microcapsule was thermally stable up to $220^{\circ}C$. The controlled release of the citronella oil present in the microcapsule core in a methanol medium was demonstrated by ultraviolet spectroscopy showing that the amount of released citronella oil was increased with increasing time. It was observed that the amount of released citronella oil was increased with increasing stirring speed and emulsifier concentration in the rnicrocapsule preparation step. Polyurethane microcapsules containing citronella oil showed excellent anti-moth property.

• Journal of the Korean Wood Science and Technology
• /
• v.46 no.5
• /
• pp.565-576
• /
• 2018

Cellulose acetate (CA) has been widely utilized for composite materials due to its high transparency and thermal resistance. In this study, CNCs (cellulose nanocrystals) were reinforced in CA nanocomposites for fortifying mechanical properties of the composites. In addition, CA nanocomposites reinforced with CNCs were manufactured by extrusion/injection processes applied with CNC-predispersion method for achieving a high dispersion level of CNCs in the CA matrix. According to the analysis of mechanical properties, the CA nanocomposite with 3 wt% CNCs has the highest tensile and flexural strengths due to the reinforcing effect of CNC nanoparticles. Thermogravimetric analysis (TGA) showed that the addition of acid hydrolyzed CNCs slightly lowered the initial pyrolysis temperature of CA nanocomposite.