• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1998.10a
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• pp.30-30
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• 1998

Solid rocket motor case의 internal insulator로 미가류 형태의 내열재에 적당하게 tacky성과 삭막 특성을 고려한 조성을 개발하여 시스템에 성공적으로 적용하였다. 개발된 내열재의 주요 조성으로는 base polymer로 EPDM과 CR을 80/20으로 blend하여 적용했으며, 삭막 특성 향상을 위해 아라미드 섬유인 Kevlar 29를 5 phrs, Hydrated silica인 Zeosil 155를 30phrs 적용하였다. 이와 같은 조성으로 제작된 내열재는 삭마시험, 인장시험, 열특성시험 등 각종 특성시험을 수행하여 시스템에 적용하기 위한 성능을 확인하고 공정에 적용하였다. ST-8 표준 모타에 적용하여 삭막시험한 결과 삭마율 0.21mm/sec를 얻었고, 추진기관 사용 온도인 -4$0^{\circ}C$-6$0^{\circ}C$ 온도 범위에서 기계적성질 값을 측정하여 성능 저하가 없는 안정된 값을 얻었으며, DSC로 Tg point 측정 결과 -55$^{\circ}C$로 나타나 저온특성이 우수한 EPDM 내열재 특성을 확인할 수 있었다.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1419-1421
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• 1998

Many kind of factors have influence on the electrical properties of polymer such as mechanical stress, impurity, additives, chemical blend, interfacial phenomena and so on. In this study, we lay emphasis on interfacial phenomena which is important part in insulating design of power cable. The electrical conduction characteristics of XLPE film are investigated as a function of different electrode materials in MIM Interfaces.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.237-240
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• 2002

Amino terminated polyetherimide(ATPEI) has been synthesized by bisphthalic anhydride arid m-phenylenediamine, after that characterized by differential scanning calorimetry(DSC), thermogravimetric analyzer(TGA). Fourier transform (FT-IR) spectroscopy and gel permeation chromatography(GPC). ATPEI was blend to improve the toughness of bisphenol-A type epoxy resin which was cured by nadic methyl anhydride(NMA). The fracture toughness and the molphology of the toughened epoxy resin was evaluated. The toughness of ATPEI modified epoxy resin was higher than that of the PEI modified epoxy resin. In addtion, carbon fiber/ATPEI modified epoxy resin composites were fabricated and the mechanical properties of the resulted composites were investigated.

• Macromolecular Research
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• v.10 no.3
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• pp.145-149
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• 2002

Transesterification between poly(trimethylene terephthalate) (PTT) and bisphenol-A-polycarbonate (PC) is studied by differential scanning calorimetry (DSC) and nuclear magnetic resonance (NMR) spectroscopy. When the blend of PTT/PC is annealed at higher temperatures, the samples do not show any melting peak at an initial stage, indicating the samples completely lose their crystallinity due to the formation of random copolymers. However, when the random copolymer is annealed at temperatures lower than the melting temperature of PTT, a melting peak is observed, indicating that the random copolymers are sequentially reordered. The melting point and the heat of fusion of crystals formed from the crystallization-induced sequential reordering depend upon the annealing temperature and time. The average sequence length determined from NMR is increased as the blocks are regenerated.

• Rubber Technology
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• v.7 no.1
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• pp.8-16
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• 2006

Plastic/rubber blends are ultrasonically treated during continuous extrusion in order to investigate the in-situ compatibilization of the blends without any chemicals. The mechanical properties of each blend were significantly improved by ultrasonic treatment. It is believed that ultrasonic treatment of the blends enhances intermolecular interaction, improves adhesion at the interface and creates copolymers during very short time. The created copolymers are believed to be a major reason for enhancing mechanical properties of the blends by in-situ compatibilization during extrusion. This process can be applied fur preparing plastic/rubber blends to make thermoplastic elastomers or plastic/plastic and rubber/rubber blends, and for making novel copolymers from practically any pairs of existing polymers to achieve desirable chemical and physical properties.

• Macromolecular Research
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• v.10 no.4
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• pp.209-214
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• 2002

Miscibility of polysulfone (PSf) with various hydrophilic copolymers was explored. Among these blends, PSf gives homogeneous mixtures with poly(1-vinylpyrrolidone-co-styrene) copolymers [P(VP-S)] when these copolymers contained VP from 68 to 88 wt%. Microporous membranes for the ultrafiltration process were prepared from PSf blends with P(VP-S) copolymers. The membranes prepared from the PSf/(VP-S) blends exhibited higher water flux than the membranes prepared from PSf irrespective of the VP content. The solute rejection examined with the membranes fabricated from the miscible blends was similar to that of PSf membrane. However, the solute rejection examined with the membranes fabricated from the immiscible blends was lower than that of PSf membranes.

• Journal of the Korean Applied Science and Technology
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• v.16 no.1
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• pp.67-73
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• 1999

Chitosan and Algin are known as a natural polymers. Biodegradable films were prepared by solution blend method in the weight ratio of natural polymer(low, medium, high-Chitosan, Algin) for the purpose of useful bioimplants. The possibility of bioimplants, which were prepared from natural polymers as a skin substitute and food wrapping materials were evaluated by measuring biodegradability. This biodegradable films were inserted in the back of rats and their biodegradability was investigated by hematological change evaluation as a function of time to biotransformation. It was found that these values of biodegradable films give some good results with short period test.

• Elastomers and Composites
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• v.50 no.3
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• pp.159-166
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• 2015

Silica which is used for reinforcing filler in tire industry is widely known as eco-friendly material exerting $CO_2$ reduction effect through decrease of rolling resistance and improvement of wet grip. Generally silica is classified as a highly polar filler because it contains a large number of silanol (Si-OH) group on its surface. And also silica gives a lower reinforcing effect than carbon black due to its poorer rubber-filler interaction. Therefore silica is treated with silane coupling agent or activator, then following the conventional rubber blend method, vulcanized sheets were prepared using a hot press, and cure characteristics, mechanical properties and abrasion resistance of the test specimens were investigated. It was found that with an increase in the silane coupling agent content the tensile strength, 300% modulus and abrasion resistance increased while Mooney viscosity decreased and crosslink density slightly increased with an increase of activator.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.505-509
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• 2013

A low temperature ($65^{\circ}C$) thermal deposition process was developed for depositing a silver coating on thermally sensitive polymeric substrates. This low temperature deposition was achieved by chemical reduction of a silver alkylcarbamate complex with latent reducing agent. The effects of acetol as a latent reducing agent for the silver 2-ethylhexylcarbamate (Ag-EHCB) complex and their blend solutions were investigated in terms of reducing mechanism, and the size and shape of silver nanoparticles (Ag-NPs) as a function of reduced temperature and time, and PVP stabilizer concentration were determined. Low temperature deposition was achieved by combining chemical reduction with thermal heating at $65^{\circ}C$. A range of polymer film, sheet and molding product was coated with silver at thicknesses of 100 nm. The effect of process parameters and heat treatment on the properties of silver coatings was investigated.

• Fibers and Polymers
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• v.5 no.4
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• pp.270-274
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• 2004

Blends of poly(l-lactide) (PLA) and low density polyethylene (LDPE) were prepared by melt mixing in order to improve the brittleness of PLA. A reactive compatibilizer with glycidyl methacrylate (GMA), PE-GMA, was required as a compatibilizer due to the immiscibility between PLA and LDPE. It contributes to reduce the domain size of dispersed phase and enhance the tensile properties of PLA/LDPE blends, especially for PLA matrix blends. A reaction product between PLA and PE-GMA, which was formed during melt-mixing and considered to act as a reactive compatibilizer, was characterized using $ ^1H-NMR$ spectroscopy.