• Bulletin of the Korean Chemical Society
• /
• v.11 no.3
• /
• pp.245-248
• /
• 1990

A series of compounds were synthesized that contain varying number of mesogenic units, 4-n-butylazobenzene moiety, attached to the central benzene ring through ester bond. These compounds were subjected to thermal analysis on a differential scanning calorimeter (DSC) and also on a polarizing microscope. It was found from this study that the presence of mesogenic units in a multi-mesogenic compound does not guarantee for the compound to become mesomorphic and that the linear molecular shape is conducive to form a liquid crystalline phase.

• Polymer(Korea)
• /
• v.25 no.6
• /
• pp.811-817
• /
• 2001

Crystallization behaviour of bisphenol A polycarbonate(PC) from amorphous phase was studied by varing solvent/nonsolvent ratios in liquid phase. Chloroform and isopropanol were used as a solvent and a nonsolvent, respectively. Samples were characterized by optical microphotography, scanning electron microscope (SEM), X-ray diffaction (XRD), and differential scanning calorimeter (DSC). DSC and XRD measurement were used to determine the crystallinity of PC. The solubility constant seems to critical to control the PC crystallinity in solvent/nonsolvent mixture. The difference in PC crystallinity is explained by the difference in solubility constant of the mixture depending on the solvent/nonsolvent ratio. PC solution of 75/25 wt% (solvent/nonsolvent) ratio produced PC powder showing maximum crystallinity. At this condition solubility constant (9.85) of the mixed solvent was close to PC (9.9).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.330-333
• /
• 1997

The thermal impact of mica/epoxy paper(130${\mu}{\textrm}{m}$) is investigated using XRD, DSC and TGL X-ray diffraction(XRD) analysis was performed to know the position and structure of mica crystal in insulation materials. A differential scanning calorimeter(DSC) was used to measure glass transition temperature and excess enthalphy of the composite materials that had been subjected to thermal aging. The glass transition temperature(T$_{g}$) measured by DSC is observed at 95.43$^{\circ}C$ and 113.43$^{\circ}C$, respectively. The T$_{g}$ also increases with increased aging time. Measurements performed by TGA(thermogravimetric analysis) have showed that weight loss profile of sound specimens are lower than those aged.ged.

• Composites Research
• /
• v.24 no.4
• /
• pp.5-10
• /
• 2011

As environmental pollution getting worse, biodegradable materials have been drawn more attention than ever. In this study, polylactic acid (PLA)/carbon nanotubc (CNT) nanocomposites were manufactured via extrusion molding and injection molding, In order to change the crystallinity, annealing treatment was done for different time span, Crystallization kinetics of PLA was analyzed by differential scanning calorimeter (DSC), and it was confirmed that a proper amount of CNT can increase the crystallization rate of PLA. In addition, the presence of CNT significantly accelerates the hydrolytic degradation rate of PLA, however, it decreases with the increase of crystallinity. The reason is that degradation may occur in the PLA/CNT interface easily, and the molecular structure of the composite becomes dense with the increase of crystallinity.

• The Korean Journal of Pharmacology
• /
• v.26 no.1
• /
• pp.77-82
• /
• 1990

The effects of phenothiazine derivatives and calcium on the thermotropic phase transition of bilayers in dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidic acid (DPPA) liposomes were investigated with differential scanning calorimeter (DSC). Bilayers underwent an abrupt organizational changes at a characteristic temperature when heated. Such temperature-dependent transition was particularly striking and sharp in the bilayers prepared from pure phospholipids. The ability of phenothiazine derivatives to modify the phase transition of phospholipids liposomes was measured by a broadening of the phase transition profile, that transition began to appear at lower temperature than which occurs in untreated liposomes. Calcium ion caused a large upward shift in the transition temperature of DPPC:DPPA (34:66mol%) liposomes. When the liposomes were first incubated with calcium ion followed by phenothiazine derivatives, disappearance of the broad curve centering at $73^{\circ}C$ indicated displacement of calcium ion by phenothiazine derivatives at the anionic site. It is supposed that calcium ion and phenothiazine derivatives might compete with each other on the head group of acidic phospholipid.

• Fire Science and Engineering
• /
• v.15 no.2
• /
• pp.1-5
• /
• 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
• /
• v.32 no.2
• /
• pp.175-180
• /
• 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
• /
• v.20 no.4
• /
• pp.135-139
• /
• 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
• /
• v.35 no.4
• /
• pp.545-550
• /
• 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.

• Journal of Advanced Marine Engineering and Technology
• /
• v.28 no.6
• /
• pp.962-971
• /
• 2004

This paper has dealt with thermo-physical properties of microencapsulated phase change material slurry as a latent heat storage material having a low melting point. The measured results of the thermo-physical properties of the test microencapsulated phase change material slurry, those are, density, specific heat, thermal conductivity and viscosity, were discussed for the temperature region of solid and liquid phases of the dispersion material (paraffin). The measurements of these properties of microencapsulated phase change material slurry have been carried out by using a specific-gravity meter, a water calorimeter, a differential scanning calorimeter(DSC), a transient hot wire method and rotating type viscometer, respectively. It was clarified that the additional properties law could be applied to the estimation of the density and specific heat of microencapsulated phase change material slurry and also the Euckens equation could be applied to the estimation of the thermal conductivity of this slurry.