• 접착 및 계면
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• 제7권4호
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• pp.32-38
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• 2006

A series of organic-inorganic hybrids, PCL/EP/$SiO_2$, involving epoxy resin and triethoxysilane-terminated polycaprolactone elastomer (PCL-TESi) were prepared via polymerization of diglycidyl ether of bisphenol A (DGEBA) with amine curing agent KB-2 and sol-gel process of PCL-TESi. The curing reactions were started from the initially homogeneous mixture of DGEBA, KB-2 and the PCL-TESi. The organicinorganic hybrids containing up to 4.95% (wt) of $SiO_2$ were obtained and characterized by FT-IR, transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA). It was experimentally shown that the swelling property in toluene, morphologies and thermal properties of the resulting hybrids were quite dependent on the contents of $SiO_2$. The crosslink network density decreases with increasing of the PCL-TESi. And in TEM, the phase separated morphology of these hybrids was found, which resulted from the coagulation of Si-O-Si networks resulting from $-Si(OC_2H_5)_3$ of PCL-TESi self-curing by hydrolytic silanol condensation, with the advancement of the curing reaction in the modified epoxy resin systems. Meanwhile, the change of the $SiO_2$ content made the morphologies changed from aggregated particles of Si-O-Si in the hybrid to nanocluster of interconnected Si-O-Si particles, then to aggregated Si-O-Si dispersing in the continuous cured epoxy phase again, and last to co-continuous interpenetrating network. The glass transition behavior of the hybrid material was cooperative motion of large chain segments, which were hindered by the inorganic Si-O-Si network. And in TG analysis, the characteristic temperature at 5% of weight loss was evidently increased from $120.5^{\circ}C$ of pure cured epoxy to $277.6^{\circ}C$ of 3.84% (wt) of $SiO_2$ modified epoxy due to the existence of Si-O-Si when PCL-TESi was added in the hybrid.

• Macromolecular Research
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• 제13권2호
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• pp.135-140
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• 2005

Poly(vinyl alcohol) (PVA) membranes crosslinked with poly(acrylic acid-co-maleic acid) (PAM) were prepared to investigate the effect of aging on their morphology by swelling them for up to 7 days. PAM was used both as a crosslinking agent and as a donor of the hydrophilic-COOH group. A $30 wt\%$ weight loss of the dry membrane was observed in the swelling test after 6 days. The surface of the membrane was dramatically changed after the swelling test. The surface roughness of the PVA/PAM membrane was increased, as determined by atomic force microscopy (AFM). The swelling loosened the polymer structure, due to the release of the unreacted polymer and the decomposition of the ester bond, thereby resulting in an increase in the free volume capable of containing water molecules. The water molecules present in the form of free water were determined by differential scanning calorimetry (DSC). The fraction of free water increased with increasing swelling time. The swelling of the membrane may provide space for the transport of protons and increase the mobility of the protonic charge carriers. The proton conductivity of the membranes measured at T= 30 and $50^{\circ}C$ was in the range of $10^{-3} to 10^{-2} S/cm$, and slightly increased with increasing swelling time and temperature.

• 폴리머
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• 제37권3호
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• pp.332-341
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• 2013

H-shaped amphiphilic pentablock copolymers $(PSt)_2-b-PCL-b-PEO-b-PCL-b-(PSt)_2$ was synthesized via chemoenzymatic method by combining enzyme-catalyzed ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (${\varepsilon}$-CL) and atom transfer radical polymerization (ATRP) of styrene. By this process, we obtained copolymers with controlled molecular weight and low polydispersity. The structure and composition of the obtained copolymers were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and infrared spectroscopy analysis (IR). The crystallization behavior of the copolymers was analyzed by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The crystallization behavior of the H-shaped block copolymers demonstrated a PCL dominate crystallization. The self-assembly behavior of the copolymers was investigated in aqueous media. The hydrodynamic diameters of the copolymer micelles in aqueous solution were measured by dynamic light scattering (DLS). The morphology of the copolymer micelles was observed by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The hydrodynamic diameters of spherical micelles declined gradually with the increase of the hydrophobic chain lengths of the copolymers. The critical micelle concentration (CMC) values were determined from fluorescence emission, and it was found that the CMCs decreased with an increase of PSt hydrophobic block lengths.

• 소성∙가공
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• 제7권4호
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• pp.333-339
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• 1998

Hot torsion tests were conducted to investigate the high temperature deformation behavior of $Al_{85}Ni_{10}Y_5$ alloy extrudates fabricated with amorphous ribbons. The powder metallurgy routes, hot pressing and hot extrusion were used to fabricate the extrudates. Thermal properties of amorphous ribbons with different thickness as a function of aging temperature were studied by thin film x-ray dif-fraction (XRD) and differential scanning calorimetry(DSC). The Al phase crystallite firstly formed in the amorphous ribbons and its crystallization temperature($T_x$)Was ~210${\circ}C$ During the processings of consolidation and extrusion, nano-grained structure(~100 nm) was formed in the Al85Ni10Y5 alloy extrudates. The as-extrudated Al85Ni10Y5 alloy and the $Al_{85}Ni_{10}Y_5$ alloy annealed at 250${\circ}C$ for 1 hour showed a flow curve of DRV(dynamic recovery) during hot deformation at 400-550${\circ}C$. On the other hand, the $Al_{85}Ni_{10}Y_5$ alloy annealed at 400${\circ}C$ for 1 hour showed a flow curve of DRX(dynamic recrys-tallization) during hot deformation at 450-500${\circ}C$. Also the flow stress and flow strain of the $Al_{85}Ni_{10}Y_5$ alloy extrudate annealed at 400${\circ}C$ were higher than those at 250${\circ}C$.

• 마이크로전자및패키징학회지
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• 제14권4호
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• pp.21-25
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• 2007

본 연구에서는 시차주사열량법, 젖음성 시험기, 비커스 경도계와 인장 시험기를 이용하여 Sn-0.7wt%Cu-Xwt%Re(X=$0.01{\sim}1.0$) 솔더의 특성에 관하여 평가하였다. 희토류 금속의 함량이 증가함에 따라 솔더의 용융 온도가 약간 상승하는 경향을 나타내었으나 $0.01{\sim}1.0%$의 희토류 금속이 첨가된 범위에서는 $233.9{\sim}234.7^{\circ}C$의 작은 용융 온도 범위를 갖는 것을 확인할 수 있었다. 솔더의 젖음성 시험 결과로부터 Sn-0.7Cu-0.1Re 솔더의 젖음성이 다른 솔더보다 우수한 것을 확인할 수 있었으며, Sn-0.7Cu-0.1Re 솔더의 젖음성이 Sn-0.7wt%Cu-0.01wt%P 솔더보다 우수한 것을 확인할 수 있었다. 또한 희토류 금속의 함량이 증가할수록 솔더의 경도와 인장 강도가 증가하는 경향을 확인할 수 있었다.

• KSBB Journal
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• 제10권2호
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• pp.149-158
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• 1995

각종 CD와 여러 종류의 화합물, pH indicator, biostain, 아미노산, 천연배당체, 그리고 fatty acid 간의 inclusion complex 형성능을 비교하였다. Fatty acid가 각종 CD에 대한 포접형성능과 선택성 이 높아 CD 분리용 ligand로 적합함을 알았다. Fatty acid의 포접능과 선택성은 탄소쇄의 길이와 밀접한 상관관계를 나타내어 capric acid는 ${\alpha}$- CD와 palmitic acid는 ${\beta}$-CD와 높은 선택성을 보였다. Complex형성에 미치는 반융조건인 흔합 농도비, pH, ionic strength, 그리고 온도의 영향을 검토하였다. 적정 혼합 농도비는 CD가 50mM 그리고 lig and 인 fatty acid가 50mM 일 때 였으며 , 온도가 중 요한 형성조건으로 작용하였다. 포접되지 않은 CD 와 fatty acid가 포접 된 CD의 분자구조를 X-ray diffraction과 IR spectrum을 사용하여 비교 검토하였으며, DSC로 inclusion complex 형성반응의 en­t thalpy의 변화값(${\gamma}H$)을 측정하여 발열반응임을 확인하였다.

• E2M - 전기 전자와 첨단 소재
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• 제7권2호
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• pp.138-144
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• 1994

Electrical conduction phenomena of $C_{22}$-quinolium(TCNQ) Langmuir- Blodgett(LB) films are reported through a study of current-voltage(I-V) characteristics along a perpendicular direction. The I-V characteristics were investigated by applying a step or a pulse voltage to the specimen as well as changing temperatures in the range of 20-250[.deg. C] It show an ohmic behavior in low-electric field, and a nonohmic behavior in high-electric field. This nonohmic behavior has been interpreted in terms of a conduction mechanism of space-charge limited current and Schottky effect. When the electric field is near the strength of 10$_{6}$ V/cm, there occur anomalous phenomena similar to breakdown. When step or pulse voltage is applied, the breakdown voltage shifts to the higher one as the step or pulse time width becomes shorter. To see the influence of temperature, current was measured as a function of temperature under the several bias voltages, which are lower than that of breakdown. It shows that the current increases to about 103 times near 60-70[.deg. C], and remains constant for a while up to around 150[.deg. C] and then suddenly drops. We have also performed a DSC(differential scanning calorimetry) measurement with $C_{22}$-quinolium(TCNQ) powder in the range of 30-300[.deg. C]. These results imply that the anomalous phenomena occuring in the high electric field are caused by the electrical and internal thermal effect such as a joule heating.ating.

• 한국식품조리과학회지
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• 제5권2호
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• pp.43-50
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• 1989

탈지한 분질과 점질 감자전분의 형태 및 크기, 이화학적 성질, 호화 특성을 생전분과 비교하였다. 감자전분 입자는 복굴성을 갖는 원형이나 타원형으로 평균 크기가 $22.5~29.8\mu\textrm{m}$이었다. 물결합 능력, 팽윤력 및 용해도는 남작 전분이 데지마 전분보다 낮게 나타났으며 탈지 후에는 두 전분 모두 물결합 능력과 용해도는 감소하였으나 팽윤력은 약간 증가하였다. X-선 회절도에 의한 상대적 결정도는 탈지 후에 다소 감소하였다. 남작과 데지마 생전분의 blue value는 각각 0.37과 0.35이었으나 탈지 후 0.29및 0.28로 낮아졌다. 광투과도는 생전분보다 탈지전분이 더 높았다. DSC에 의한 호화 개시 온도는 생전분의 경우 남작 전분이 데지마 전분보다 높게 나타났으며 생전분의 호화엔탈피도 남작 전분이 더 컸으나 탈지후에는 두 전분 모두호화 엔탈피가 감소하였다.

• 한국식품조리과학회지
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• 제13권5호
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• pp.627-634
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• 1997

동부앙금의 단백질 함량이 높을수록 물결합력과 호화 개시 온도는 높았으나 팽윤력과 용해도, 광투과도는 낮은 값을 보였다. 최고 점도와 breakdown은 낮았으나, consistency와 setback은 높은 값을 보였다. 동부겔을 24시간과 48시간 실온에서 저장하면서 실시한 관능검사 결과는 단백질 함량이 높을수록 색깔과 투명도가 더 높은 값을 보였고 저장기간이 길수록 견고성, 응집성, 탄성, 종합적인 맛에서 더 높은 값을 보였으며 기계적 물성 검사 결과는 24시간 저장한 동부겔에서는 견고성, 껌성, 씹힘성의 특성치에서 단백질 함량이 높을수록 유의적으로 높았다. 그리고 48시간 저장한 동부겔에서는 견고성, 응집성, 껌성, 씹힘성의 특성치에서 유의적인 차이를 보였는데 응집성만 단백질 함량이 높을수록 더 낮은 값을 보였다.

• 한국식품영양학회지
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• 제31권4호
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• pp.511-519
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• 2018

The baking properties of rice bread with different percentages of butter and oil in wet and dry rice flour were investigated. The moisture, damaged starch, mean diameter, pasting properties by amylogram and RVA (Rapid Visco Analyzer), as well as thermal properties by DSC (Differential Scanning Calorimetry) of wet and dry rice flour were analyzed. The specific gravity and color (L, a, b) of the dough, as well as the appearance, color (L, a, b) and texture of the rice bread with different percentages of butter and oil in wet and dry rice flour were also analyzed. As a result, the wet rice flour were composed of a noted higher content in moisture, compared to the dry rice flour (p<0.001). The wet rice flour had lower values of damaged starch, higher values of mean diameter and a higher peak viscosity than was noted in the dry rice flour (p<0.001). The wet rice flour showed a higher degree of hydration and gelatinization than was seen in the dry rice flour (p<0.001). The prevailing principle to utilize the replacement of wet rice flour with oil had a significant effect on the volume, specific volume and hardness of the rice bread (p<0.001). The hardness of the rice bread also showed a decreasing trend as the amount of the added oil was increased into the mixture. These results suggest that the replacement of wet rice flour with 5.8% oil is effective for the production of rice bread.