• 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.

• Fire Science and Engineering
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• v.15 no.2
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• pp.1-5
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• 2001

We had investigated combustion properties of starch. Decomposition of starch scavenged by pre-cipitator of spinning factory with temperature were investigated using DSC and TGA. Combustion properties of starch according to amount were checked as temperature variation according to time using spontaneous ignition apparatus. Moreover, combustion properties with blowing or without blowing condition were checked in spontaneous ignition apparatus. As results of thermal analyses, increase in raising temperature causes initial smoldering temperature to move towards low temperature section. In addition, as amount of starch was increased, initial smoldering temperature was lowered. All of combustion forms were smoldering combustion. Initial smoldering temperature was low more slightly with blowing condition than without blowing condition in spontaneous ignition apparatus, which condition made heating value high.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.2
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• pp.175-180
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• 2003

Effect of the addition of maltitol to Korean rice cake (Karedduk) on its retrogradation was examined. Degree of retrogradation was also examined in terms of recrystallinity of starch and color change with a differential scanning calorimeter. As a result, retrogradation was suppressed by the increasing addition of maltitol. In particular, enthalpy showed a tendency to decrease at $25^{\circ}C$ rather than at 4$^{\circ}C$ during 4 days. In the gelatinization properties using DSC, onset temperature (To) was shown to increase slightly according to storage time. Maximum peak temperature (Tp) was shown to decrease by the addition of maltitol during 4 days. Melting enthalpy was decreased at $25^{\circ}C$ and 4$^{\circ}C$ by the addition of maltitol. The analysis X-ray diffraction also revealed that retrogradation of the Korean rice cake was suppressed by the addition of maltitol because crystalline region did not appear. The addition of maltitol into the Korean rice cake was found to result in an increase of its qualify or color stability.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.135-139
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• 2019

In this work, flame retardant acrylic emulsion pressure sensitive adhesives were newly polymerized combining phosphorous flame retardant monomer and acrylic monomer like butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, and 2-hydroxyethyl methacrylate. The process of polymerization showed 100% of conversion at solid content of 65%, and viscosity of acrylic emulsion was increased up to 5500 cps when phosphorous flame retardant monomer was added into acrylic emulsion. The structure of flame retardant acrylic emulsion was identified using FT-IR and thermal properties like glass transition temperature (Tg) were checked by differential scanning calorimeter (DSC). Acrylic emulsion without phosphorous flame retardant monomer had Tg of -44.1℃ and peel strength of 2,100gf/inch, however, flame retardant acrylic emulsion showed maximum Tg (-31.4℃) and peel strength of 200gf/inch when 15 part of phosphorous flame retardant monomer was added. Flammability test was also conducted to confirm the application of flame retardant acrylic emulsion as the flame retardant addtive.

• Korean Journal of Food Science and Technology
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• v.35 no.4
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• pp.545-550
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• 2003

The effect of ${\beta}-glucan$ on gelatinization of barley starch was studied. By the rapid visco-analyzer measurement, gelatinization of starch became rapid and viscosity increased largely on the RVA pattern by addition of ${\beta}-glucan$ to starch. The results of differential scanning calorimeter showed that molecular structure of starch was getting stabilized through shifting up of gelatinization temperature and increase in enthalpy by addition of ${\beta}$-glucan. X-ray diffraction pattern also showed the same results as differential scanning calorimeter. But it was revealed that addition of ${\beta}$-glucan to starch didn't affect characteristics such as microscopic observation, solubility, swelling power, and iodine binding properties during gelatinization of starch.

• Composites Research
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• v.27 no.3
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• pp.90-95
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• 2014

Cure shrinkage during cure process of polymer matrix composites develope residual stress that cause some structural deformation, such as spring-in, spring-out and warpage. The carbon/epoxy prepreg used in this study is Hexply M21EV/34%/UD268NFS/IMA-12K supplied by Hexcel corp. Cure shrinkage and degree of cure measured by TMA(thermomechanical analyzer) and DSC(differential scanning calorimetry). Cure shrinkages are measured by TMA within a temperature range of $140{\sim}240^{\circ}C$ in a nitrogen atmosphere, and degree of cure determined by the heat of reaction using dynamic and isothermal DSC runs in argon atmosphere. As a result, the cure shrinkage is increased dramatically in a degree of cure range between 27~80%. the higher the cure temperature, the lower the degree of cure occurring to begin cure shrinkage.

• Journal of the Korean Society of Safety
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• v.30 no.4
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• pp.8-13
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• 2015

The magnetic shape memory alloys have recently received a lot of attention due to the considerable progress achieved in understanding the particular importance and the development of the factors. Among these alloys, the ferromagnetic Co-Ni- alloys have been concerned specially because of the thermoelastic character of the fcc (g) - bct (a) martensitic transformation which exhibits under the action of the temperature (shape memory effect), the stress (superelasticity) and the magnetic field (magnetoelasticity). The morphological, the crystallographical, and the thermal characteristics of thermally induced martensite in Co-35.3Ni-11.3Al(wt.%) and Co-28.1Ni-47.4Fe-3.3Ti (wt.%) alloy have been investigated by the scanning electron microscope (SEM), the X-ray Diffraction (XRD), and the differential scanning calorimeter (DSC).

• Journal of Sericultural and Entomological Science
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• v.42 no.1
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• pp.42-47
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• 2000

Structural and thermal characteristics of silk fibroin/poly(2-hydroxyethyl methacrylate)(PHEMA) blend films were investigated using FTIR, X-ray diffractometer, differential scanning calorimeter, thermogravimeter and scanning electron microscope. FTIR spectra showed that the conformation of silk fibroin prepared by dissolving in formic acid was $\beta$-sheet, which did not affected by blending with PHEMA. The X-ray diffraction patterns also showed that individual crystalline structure of silk fibroin and PHEMA was not affected for the blend films. The initial thermal decomposition temperature of silk fibroin/PHEMA blend film tends to be higher than either of silk fkbroin or PHEMA. Thermal stability of both polymers, more notably PHEMA, can be improved by blending two components. As a result of SEM observation, the phases separation for silk fibroin/PHEMA blend films occured regardless of blend ratio ; continuous and dispersed phase were silk fibroin and PHEMA component, respectively.

• Proceedings of the KOSOMBE Conference
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• v.1989 no.05
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• pp.9-12
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• 1989

A preliminary study has been conducted to demonstrate the effect of laser heat treatment on Ni Ti alloy dental arch wires ($0.016"\;{\times}\;0.022"$ and $0.018"\;{\times}\;0.026"$, rectangular shape). Changes in mechanical and thermal properties and surface morphologies are investigated by using optical and scanning electron microscope (SEM), energy dispersive x-ray microprobe analysis(EDX), differential scanning calorimeter (DSC), and micro hardness tester. The results indicate that the laser can affect the thermal equilibrium state of the localized surface. Titanium rich surface film is formed by the laser treatment. The surface film and rapidly resolidified underlying structures show better chemical resistance than the matrix material. Phase transition temperatures which are related to shape recovery temperatures are changed after laser treatment. Hardness of resolidified area and heat affected zone are lower than before treatment.

• Journal of Sericultural and Entomological Science
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• v.40 no.2
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• pp.163-168
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• 1998

Hydrolysis rate and activation energy of Antheraea pernyi silk fiber treated with HCI were examined. Thermal decomposition temperature and surface morphology were also investigated by using differential scanning calorimeter and scanning electron microscope. As the concentration of hydrochloric acid and the treatment temperature increased, the hydrolysis occurred more rapidly. The activation energy of Antheraea pernyi, 74.0 kJ/mol, was higher than that of Bombyx mori, 58.1 kJ/mol. As the concentration of hydrochloric acid increases, the activation energy of Antheraea pernyi decreased from 74.0 kJ/mol to 62.0 kJ/mol. The shape of acid-resistance fraction of Antheraea pernyi became more distroyed and was transformed from fiber to powdered form with an increase of hydrolysis rate. The thermal decomposition temperature of Antheraea pernyi was 360.8$^{\circ}C$ until the hydrolysis rate was 81.8 wt%, but ti decreased to 347.0$^{\circ}C$ when the hydrolysis rate was 93.8 wt%.