• Elastomers and Composites
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• v.21 no.1
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• pp.13-19
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• 1986

The effects of several vulcanizing accelerators on the determination of kinetic parameters of natural rubber vulcanizate was studied by DSC. Kinetic parameters were determined by means of the calculation procedures of Borchardt-Daniels and Oscillating Disk Rheometer (ODR) cure curve analysis, using both DSC exothermal thermogram and ODR cure curve. In order to examine the credibility in the DSC method the same compound which was und for DSC method was used for the comparison with the results of ODR data. Upon this method, kinetic rate constant (k), and Arrehenius parameter (Ea, ko, n) have been determined for rubber compounds via a new method using DSC thermogram and ODR cure curve. In the comparison of DSC and ODR results, kinetic parameters has shown good agreements between two results. Consequently, from the present studies, it is shown that the DSC thermoanalytical method can provide an alternate new method of kinetic study of rubber vulcanization.

• Korean Chemical Engineering Research
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• v.50 no.3
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• pp.442-448
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• 2012

The effects of zeolite-type catalysts addition on the thermal decomposition of the PP resin have been studied in a thermal analyzer, a Pyrolyser GC-mass, and a small batch reactor. The zeolite type catalysts tested were natural zeolite, used FCC catalyst, and ZSM-5. As the results of TGA experiments, the pyrolysis starting temperature for PP varied in the range of $330{\sim}360^{\circ}C$ according to the heating rate. Addition of the zeolite type catalysts in the PP resin increased the pyrolysis rate in the order of used FCC catalyst> natural zeolite> ZSM-5 > PP resin. Adding the used FCC catalyst in the PP reduced most effectively the pyrolysis finishing temperature. In the PY-G.C. mass experiments, addition of zeolite type catalysts decreased the molecular weight of pyrolyzed product. In the batch system experiments, the mixing of used FCC catalyst enhanced best the initial yield of fuel oil, but the final yield of fuel oil was 2% higher in the case of mixing of natural zeolite. Also in the carbon number analysis, used FCC catalyst was the most useful one in this experiments for fuel oil.

• Journal of the Korean Institute of Gas
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• v.2 no.1
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• pp.59-65
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• 1998

Morphology and thermal properties of polyurethane synthesized from 4,4'-diphenylmethane diisocyanate (MDI), polyester polyol, and 1,4-butane diol are investigated using fourier transform infrared spectroscopy (FT-IR), differential scanning calorimeter (DSC), and dynamic mechanical thermal analysis (DMTA). From the FT-IR study, it is found that the stretching peaks of hydrogen bonded N-H and C=O are shifted to the low frequencies with the increase of hard segment content of the polyurethanes. The shift of the stretching peaks of hydrogen bonded N-H and C=O indicates that the degree of hydrogen bonding is increased. From the DSC study, it appears that the glass transition temperature ($T_g$) of the polyurethanes is increased with the increase of the hard segment content. Also, it is found that the polyurethanes investigated in this study have the homogeneous network structure due to the high functionality of the MDI. From the DMTA study, transition of the soft segment was not found. Therefore it is concluded that the polyurethanes investigated in this study have the one-phase morphology which is consistent with the DSC results.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.40-45
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• 2010

Entrapment of hydrophobic flavonoid luteolin into ethosome was carried out for improving its stability and making practical application in the field of drug and cosmetics. The formation of liquid crystalline phase and its thermal properties were investigated by polarized optical microscopy and DSC. The phase inversion from W/O to W/O/W was detected by conductivity change with the addition of PBS buffer solution into the ethanol-dissolved lecithin mixture. The particle size change of ethosome with constituent composition was examined, which showed that the incorporation of luteolin into lecithin up to 10% had little effect on the size of ethosome. Enhancement of stability of luteolin by entrapment into ethosome was verified through DPPH test. The stabilization efficacy of ethosome was improved further by the addition of tocopherol.

• Polymer(Korea)
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• v.34 no.6
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• pp.491-494
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• 2010

Colored, electrophoretic polymer nanoparticles of poly (styrene-co-divinylbenzene-co-vinyl acetate)[poly(St-co-DVB-co-VAc)] were prepared by emulsifier-free emulsion co-polymerization and reactive dyeing. The emulsifier-free emulsion polymerization of styrene, divinyl benzene and vinyl acetate was carried out at $70^{\circ}C$ for 20 hrs to obtain monodisperse polymer nanoparticles of poly(St-co-DVB-co-VAc) with an average diameter of 180~200 nm. These nanoparticles were transformed into poly(styrene-co-divinylbenzene-co-vinyl alcohol) [poly(St-co-DVB-co-VA)] nanoparticles through the saponification reaction. The poly(St-co-DVB-co-VA) nanoparticles were treated with reactive dyes to obtain the colored, monodisperse electrophoretic nanoparticles, and their morphology and surface charge were characterized by scanning electron microscopy, differential scanning calorimetry, UV/Vis absorbance and zeta-potentiometry.

• Polymer(Korea)
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• v.30 no.5
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• pp.380-384
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• 2006

Polyhedral oligomeric silsesquioxanes (POSS) were used as starting materials for the preparation of hybrid materials with polystyrene (PS). Optically transparent hybrids were obtained in a wide range of weight ratios when phenyl groups were introduced to each corner of the silsesquioxane. In contrast, as cyclohexyl groups were introduced, the obtained hybrid materials with PS resulted in turbid films. The aromatic (${\pi}-{\pi}$) interaction was confirmed to be a quite effective tool for the synthesis of organic-Inorganic polymer hybrids with POSS. The obtained homogeneous and transparent hybrid films could be dissolved in solvents and East again without any separation. The homogeneity of polymer hybrids with POSS was supported by the result of scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), which demonstrated a nanometer-level integration of PS and POSS.

• Clean Technology
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• v.21 no.4
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• pp.235-240
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• 2015

In this study, vanadium dioxide was doped with titanium (0~0.5 at %) to improve thermochromic properties. The titanium doped vanadium dioxide (Ti-VO₂) particles were prepared via thermolysis process using vanadyl sulfate, ammonium bicarbonate and titianium chloride as precursors. The crystal structure, morphology, chemical bonding and thermochromic properties were investigated by using XRD, FE-SEM, XPS, DSC and UV-Vis-NIR spectroscopy. It was found that titanium was successfully doped into the crystal lattice of VO₂ and the obtained Ti-VO₂ particles have monoclinic structure. With increasing Ti concentration, the particle size and phase transition temperature of Ti-VO₂ particles decreased and NIR switching efficiency increased.

• Polymer(Korea)
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• v.24 no.3
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• pp.350-357
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• 2000

Curing behaviors of glass/epoxy prepreg for printed circuit boards (PCB) were studied by using dielectrometer and differential scanning calorimeter. This prepreg was showed the lowest ionic viscosity at about 115$^{\circ}C$, and then the ionic viscosity was gradully increased up to 15$0^{\circ}C$. This indicated that the curing reaction of this prepreg started at 115$^{\circ}C$ 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 dielectric behaviors of this prepreg system were also measured according to the cure cycle for PCB. This material was found to be thermally stable up to about 30$0^{\circ}C$ and then was showed an abrupt decomposition beyond this temperature.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.660-665
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• 1999

Structure of water soluble chitosan (WSC) was confirmed by Fourier transform infrared spectrometer (FT-IR), X-ray diffractometer and thermal analyser. The viscosity average molecular weight of WSC ranged from $3.0{\times}10^{4}$ to $4.5{\times}10^{4}$. Using the WSC having viscosity average molecular weight of $3.0{\times}10^{4}$, the antimicrobacterial effects against microorganism and oral microorganism showed 81.7% and 80.6% for Staphyloccus aureus and Bacillus subtilis, respectively, while the anitmicrobacterial effect exhibited 100% and 73.8% against Streptococcus mutans and Streptococcus sanguis, respectively. Therefore it is concluded that WSC is more effective against oral microorganism that microorganism in terms of antimicrobacterial effects. WSC sample with the viscosity average molecular weight of $4.5{\times}10^{4}$ exhibited a half of the antimicrobacterial effect of the low MW sample, indicating that the WSC with low MW was better than that with high MW. Chitin and chitosan showed a drastic decrease of acidity from pH 7.0 to 4.9 after 8 minute incubation time and reached an equilibrium after that. WSC, however, restrained pH of the sample from lowering up to about 16 minutes of incubation and reached an equilibrium after that. WSC obviously showed a buffering effect against pH change.

• Polymer(Korea)
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• v.39 no.3
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• pp.506-513
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• 2015

Ethylidene norbornene (ENB) and its blends with endo-dicyclopentadiene (endo-DCPD) were prepared and reacted via the ring-opening metathesis polymerization (ROMP) reaction with the $1^{st}$ and $2^{nd}$ generation Grubbs' catalysts. Dynamic exothermic behaviors during ROMP and tensile properties after ROMP were evaluated using a differential scanning calorimeter (DSC) and a universal testing machine (UTM) for the samples, respectively. It revealed that the ROMP rate was accelerated with the less contents of endo-DCPD and under the $2^{nd}$ generation catalyst. Also, the addition of endo-DCPD and the $1^{st}$ generation catalyst resulted in higher tensile modulus and strength but lower toughness. Gel fraction measurement and fracture surface observation were made to understand the tensile properties.