• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1367-1372
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• 2010

Copoly(ether-ether-ester)s having flexible side chain were synthesized by polycondensation. Intrinsic viscosities of polymers were between 0.42 and 0.78dl/g in tetrachloroethane. The polymer structures were investigated by $^1H$-NMR and FT-IR, and thermal and liquid crystalline properties of polymers were measured by DSC, TGA, POM and XRD. As results of investigations, synthetic copolymers exhibited lower melting temperature than homopolymers. When the biphenylene units contents in copolymer were more than 60 mol %, nematic mesophase was observed, and the mesophase of synthetic polymers was dependent upon biphenylene content.

• Polymer(Korea)
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• v.25 no.6
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• pp.876-883
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• 2001

A thermotropic liquid crystalline polyester (TLCP) containing a side group was, synthesized from ethoxyhydroquinone and bromoterephthalic acid. Intercalation of TLCP in layered clays is accomplished by heating the polymer with hexadecyl ammonium-montmorillonite ($C_{16}$) above melting transition temperature ($T_m$). Liquid crystallinity of the TLCP/$C_{16}$-hybrid was observed up to 6 wt% $C_{16}$-MMT. Some of the $C_{16}$-MMTs in TLCP were highly dispersed in a nanometer scale, but some of them were agglomerated. Thermal and morphological properties of the nanocomposites were examined by differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), polarized optical microscope, and electron microscopes (SEM and TEM).

• Journal of the Korean Wood Science and Technology
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• v.42 no.6
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• pp.675-681
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• 2014

The purpose of this study is to analyze fundamental combustion characteristics of woods used for indoor applications. The combustion characteristics such as heat release rate, total heat release, gas yield, and mass loss were analyzed by the method of cone calorimeter or thermogravimetry. These analysis results show that material properties of wood are closely related to flammability. It was shown that the relationship between the mass loss and gas emission. The results of combustion properties of woods would be useful for fundamentals of guiding the safe use of wood indoor application.

• Applied Chemistry for Engineering
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• v.3 no.2
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• pp.280-287
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• 1992

Aromatic liquid crystalline polyesters were synthesized from terephthalic acid(TPA), biphenyl dicarboxylic acid(BPA) and hydroquinone(HQ) by solution polymerization. Effects of TPA/BPA ratio(by mole %) on the thermal properties, thermal stability and textures of mesophases were investigated with DSC, TGA, cross-polarized microscopy and X-ray diffractometer. The synthesized polymers in this study were thermotropic and showed nematic textures. Melting temperature($T_m$) and isotropization temperature($T_i$) of polymer increased and thermal stabilities of polymer were improved with the content of BPA. Most of the polymers in this study had crystallinity more than 30%.

• Journal of the Korean Chemical Society
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• v.46 no.2
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• pp.99-116
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• 2002

The thiazolylazo compounds and their Co(II), Ni(II) and Cu(II) complexes of barbituric acid, uracil, thiouracil, citrazinic acid, chromotropic acid, gallic acid, pyrogallol and salicylic acid were pre-pared and characterized by $^1H$ NMR , IR and the effect of pH on the electronic absorption spectra . The mode of ionization, the electronic transitions and the dissociation constants were discussed. The stoichiometries of the complexes were of 1:1, 2:1 and 3:2 (M:L). The copper complexes are of isotropic ESR spectra (except that of gallic acid which showed a complicated one) and are of magnetically diluted behaviour with orbital con-tribution. Detailed DTA data were obtained and discussed.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.582-589
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• 1987

The thermal properties of poly (ethylene terephthalate) (PET) modified by 5-sulfoisophthalic acid sodium salt(SIAS) were studied. The glass transition temperature was increased, and the melting temperature and the crystallization rate were decreased as the content of SIAS unit was increased. The decrease of crystallization rate is thought to be due to the polar, bulky sulfonic acid sodium salt group which greatly retards the crystallization on to the growing crystal surface of the diffused polymer chain. The crystallization mechanism of copolyester is dependent on the content of SIAS unit and the three dimensional growth of crystal is hindered by the added SIAS unit.

• Polymer(Korea)
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• v.24 no.3
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• pp.431-436
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• 2000

To improve the thermal and mechanical properties of homo poly(L-lactic acid), DL-mandelic acid, one of the natural $\alpha$-hydroxy acid with aromatic ring as the side-chain residue was used as the comonomer. Copolymers with different contents of mandelic acid were prepared and characterized. The resulting copolymers were mostly amorphous. As the amount of mandelic acid in the monomer feed increased, the molecular weight of the resulting polymers tended to decrease linearly. T$_{g}$ and T$_{d}$ of the copolymer, however, were found to shift toward higher temperature, suggesting the improved thermal stability by increasing content of mandelic acid moiety. Tensile measurements of cast films showed somewhat improved values in the copolymers with mandelic acid content of 5 and 10 wt%.%.%.

• Electrical & Electronic Materials
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• v.3 no.1
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• pp.36-44
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• 1990

본 연구는 34wt%(5Ce-Didymium)-Fe-1wt%B 합금의 분말입도, 성형압력 및 소결온도 에 따른 자기적 성질에 관하여 연구하였다. 그리고 각각의 자기적 성질에 영향을 주는 인자를 알아내기 위하여 밀도측정, 미세조직 및 자구를 관찰하였다. 미세조직은 금속현미경을 이용하여 관찰하였으며 자구는 Bitter법으로 관찰하였다. 결과는 아래와 같다. (1)분말의 입도와 결정립 크기가 작아질수록 경질자기 특성은 증가하였으며 소결온도가 증가할수록 경질자기 특성도 증가하였다. 그러자 압력은 1000kg/$cm^{2}$일때 가장 좋은 경질자기 특성이 얻어졌다. (2)결정립이 클수록 자구의 구조는 복잡했으며 미세한 결정립일수록 큰 결정립에 비해 큰 보자력을 갖는다. 포화된 후에는 거의 모든 결정립이 단자구였으며 열적으로 탈자되었을 경우에는 모두가 multi-domain였다. (3)가장 우수한 경질자기 특성은 3-5.mu.m의 분말을 사용하여 1080.deg.C에서 소결한 후 590.deg.C에서 열처리한 시편에서 얻어졌으며 (BH)$_{max}$는 214.6kJ.m$_{-3}$이다.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.1-4
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• 1998

전도성 고분자의 취약점인 가공성, 유연성, 용해성 등의 물리적 성질이 불량한 단점을 극복하기 위해서 물성이 좋은 범용성 고분자를 matrix 물질로 사용하여 전도성 고분자를 합성함으로써 두 가지 고분자의 복합체 또는 공중합체를 만들어 물리적 성질을 향상시키는 방법 등이 연구되고 있다. 그러나, 전도성 복합체의 경우엔 matrix로 사용된 범용성 고분자와 전도성 고분자 사이가 서로 물리적인 결합만으로 이루어져 있어, 시간이 지남에 따라 전도성 고분자의 일부가 떨어져 나가 점진적으로 전기전도도의 상실을 가져올 뿐만 아니라 열에 노출되는 경우 열적노화(thermal ageing)에 의해 전기전도도가 떨어지는 단점을 지니게 된다. (중략)

• Proceedings of the KAIS Fall Conference
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• 2000.10a
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• pp.169-172
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• 2000

본 실험에서는 광Link로 응용될 Core Glass와 Clad Glass 및 Clad용 Polymer의 조성을 개발하고, Core용 Glass 와 Clad용 Glass의 match 및 Core Glass와 Clad용 Polymer의 효과적으로 접합 성형하여 반도체제조 설비내의 모든 Data 송ㆍ수신 Link를 Optical Fiber로 대체하여 기존 전선케이블이 전자기장의 영향으로 인한 Noise 와 Data 송ㆍ수신 오류를 일으키는 것을 방지하고자 한다. 따라서, 이에 대한 연구로 우선 유리를 사용한 기초 실험을 실시하였다. 실험 과정에 있어서는 Batch 실험과 용해 실험 및 물성 측정을 통하여 최적 조건의 유리를 선정하였다. 제조된 모유리를 사용하여 유리의 열적, 기계적 성질을 측정하였다. 또한 Glass core/Glass clad 파이버를 제조하여 광학적성질, 기계적성질, 구조적 특성을 평가하였다.