• Composites Research
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• v.14 no.2
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• pp.1-7
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• 2001

The studies on the formulation and curing behaviors of Kevlar/Epoxy prepreg for NOSE CONE of aircraft were presented in this paper. Dielectrometer and differential scanning calorimeter were used in order to check the curing behaviors. This prepreg showed the lowest ionic viscosity around $120^{\circ}C$, and then the ionic viscosity was gradually increased up to $200^{\circ}C$. This indicated that the curing reaction of this prepreg started at $120^{\circ}C$ and the molecular weight was increased by the accelerated thermal cross-linking reaction. The loss factor and tan $\delta$ values were also measured and discussed. The loss factor behaviors of Kevlar/Epoxy prepreg, which is related to the fluidity of matrix, were fecund to be similar with that of ionic viscosity. The thermal reaction properties of this prepreg were also studied by differential scanning calorimeter.

• Journal of Adhesion and Interface
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• v.8 no.4
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• pp.14-22
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• 2007

In the present study, the effect of milled glass powder and liquid-type nitrile rubber (NBR) on the thermal stability of phenolic resin and the dynamic mechanical properties of glass braid/phenolic composites has been investigated by means of thermogravimetric analysis and dynamical mechanical analysis. It was found that both milled glass power and NBR filled in the waterborne phenolic resin significantly influenced the thermal stability of phenolic resins and the storage modulus and tan delta of the composites. The presence of glass powder increased the thermal stability of the phenolic resin, whereas the presence of NBR resulted in the weight loss in the specific temperature range. The thermal stability of the phenolic resins without and with the fillers was dependent not only on the cure temperature but also on the cure time. The variation of the storage modulus and tan ${\delta}$ of strip-type glass braid/phenolic composites was also influenced with the introduction of glass powder and NBR to the phenolic matrix as well as by the cure conditions given.

• Korean Journal of Materials Research
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• v.1 no.3
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• pp.151-155
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• 1991

The kinetics of isothermal crystallization in blends of poly(ethylene oxide) (PEO) and poly(styrene-co-acrylic acid) (SAA) has been examined as a function of the blend ratio, the copolymer composition, and the crystallization temperature, based on the Avrami eauation. The Avrami exponents were mostly chose to 2, independent of the crystallization temperature. The crystallization rate of PEO in PEO/SAA blends decreased with the increase of SAA content. And also, the higher the acrylic acid content in the SAA copolymer, 7he slower the crystallization rate of PEO in the blends.

• 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 Chemical Society
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• v.53 no.6
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• pp.635-639
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• 2009

Experimental work was carried out to study the combustion kinetics of the Indian coal-char in the varying mixture of carbon dioxide-oxygen ($CO_2-O_2$). The coal sample was pulverized and sieved to less than 58 microns and charred using volatile furnace by passing the nitrogen gas. The experiments were carried out using the Thermo Gravimetric Analyzer (TGA-50) at CPRI, Bangalore, different proportions of ($CO_2-O_2$) gas was allowed in to the TGA-50 (80-20, 60-40, 40-60, 20-80) mole basis were used to study the combustion kinetics of coal Isothermally, kinetic parameters like Activation energy (E) and the pre-exponential factors (A) are calculated using the unification approach and modified Arrhenius equation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.148-153
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• 2017

During natural ageing of HTPB propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behaviour at different time-temperature conditions especially focused on the in-service conditions. Ageing behaviour of HTPB propellant were investigated using HFC(Micro-Heat Flow Calorimeter) is universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Polymer(Korea)
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• v.24 no.3
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• pp.399-406
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• 2000

A thermotropic liquid crystalline polymer (TLCP) containing a flexible spacer was synthesized from hydroquinone, p-hydrofybenzoic acid, and 1,6-dibromohexane. Intercalation of TLCP in layered clays is accomplished by heating the polymer with dodecyl ammonium-montmorillonite (C$_{12}$-MMT) above melt transition temperature (T$_{m}$). Liquid crystallinity of the TLCP/C$_{12}$-MMT hybrid was not observed when $C_{12}$-MMT content was above 1 wt%. Some of the $C_{12}$-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). TEM).

• The Korean Journal of Rheology
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• v.10 no.1
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• pp.50-56
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• 1998

폴리아릴레이트(PAr)와 열방성 액정고분자(LCP)블렌드의 상용성과 두 고분자 사이 의 에스터 교환반응을 시차 주사 열분석기 (DSC)와 Fourier transform 적외선 분광분석기 (FT-IR spectroscopy)로 연구하였다. DSC를 이용하여 PAr-LCP 블렌드의 유리전이온도 (Tg)를 관찰한 결과, 두 개의 Tg가 관찰되었다. 측정된 Tg 결과로부터 블렌드 각 상에 녹아 있는 두성분의 상거동을 조사했으며 그결과 LCP가 PAR-rich 상에 녹아 들어간 양이 PAr 이 LCP-rich 상에 녹아 들어간 양보다 더 많음을 알수 있었다. 이러한 결과는 두 고분자 사 이에 부분적으로 상용성이 있음을 의미한다. 액정고분자의 이방성을 고려하여 PAr-LCP 블 렌드의 고분자-고분자 상호작용계수($\chi$12)는 0.069~0.076의 값으로 계산되었다. 두 고분자사 이의 에스터 교환반응를 조사하기 위하여 DSC내에서 열처리한 결과, 열처리 후에 PAr과 LCp의 Tg는 열처리하기 전에 비해 더 큰폭으로 두 Tg의중간값으로 이동하였다. 열처리한 PAr-LCP 블렌드를 FT-IR spectroscopy로 분석한 결과, 순수한 PAr과 LCP에 없는 새로운 에스터기의 특성피이크가 발견되었다. 이와 같은 열분석과 FT-IR spectroscopy 연구 결과 로부터 주어진 열처리 조건에서 PAr과 LCP 사이에 에스터 교환반응이 일어났음을 확인할 수 있었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.59-65
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• 2018

During natural aging, hydroxyl-terminated polybutadiene(HTPB) propellant undergoes a series of slow physico-chemical degradation reactions. By using accelerated ageing conditions it is possible to simulate the material behavior at different time-temperatures focusing on in-service conditions. Aging behaviors of HTPB propellant are investigated using HFC(heat flow calorimeter), a universal technique for measuring the rate of slow chemical and physical processes in long-term storage.

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.303-309
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• 2009

The effects of zeolite type catalysts addition on the thermal decomposition of low density polyethylene(LDPE) and ethylene vinyl acetate(EVA) resin have been studied in a thermal analyzer(TGA, DSC) and a small batch reactor. The zeolite type catalysts tested were natural zeolite, FCC catalyst, used FCC catalyst, and catalyst A. As the results of TGA experiments, addition of antifogging-agent decreased the pyrolysis point to $250^{\circ}C$, but addition of longevity-agent and clay reduced the pyrolysis rate in EVA resin. Addition of the zeolite type catalysts in the LDPE resin increased the pyrolysis rate in the order of catalyst A > used FCC catalyst > natural zeolite > LDPE resin. Addition of the zeolite type catalysts in the EVA resin increased the pyrolysis rate in the order of used FCC catalyst > natural zeolite > catalyst A > EVA resin. In the DSC experiments for LDPE resin, addition of zeolite type catalysts decreased the melting point and the heat of pyrolysis reaction in the order of catalyst A > used FCC catalyst > natural zeolite> LDPE resin. In the batch system experiments, the mixing of natural zeolite enhanced the yield of liquid fuel oil.