• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.87-94
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• 2004

The effects of pretreatment of GAC and dissolved oxygen (DO) on the sorption capacity for ο-cresol were investigated using pretreated GAC under oxic and anoxic conditions. Virgin GAC was used with pretreated GACs by $O_2$, acid and base as sorbents. Sorption capacity of GAC was dependent on the oxygen conditions according to the pretreatment methods. Virgin GAC showed increased sorption capacity when DO was present in the solution, while $O_2$-pretreated GAC did not show any considerable capacity change. Acid- and base-pretreated GACs were relatively more influenced by presence of DO as compared with virgin GAC. Both acid and base-pretreated GACs showed a rapid sorption rate at the initial stage, but as contact time became longer the sorption was slower. Sorbed ο-cresol was extracted with micro-Soxhlet extraction apparatus using the GAC separated from the rate experiments. Within 1 hour both acid and base-pretreated GACs showed the decrease in extraction efficiencies under both oxic and anoxic conditions. After 1 hour such a trend (the increase as contact time was longer) was not observed and showed relatively constant efficiencies of 35∼50%. According to the results of this study $O_2$contacted with GAC before sorption as well as DO present in the solution during sorption could influence the GAC sorption capacity.

• Macromolecular Research
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• v.12 no.3
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• pp.258-262
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• 2004

We have developed facile and rapid polycondensation reactions of N-trimellitylimido-L-leucine diacid chloride 1 with eight different derivatives of hydantoin compounds 2a-h, in the presence of a small amount of a polar organic medium, such as Ο-cresol, by using a domestic microwave oven. The polycondensation reactions proceeded rapidly-they were complete within 7-9 min-to produce a series of novel optically active poly(amide-imide)s (3a-h) in high yield with inherent viscosities of 0.33-0.51 dL/g. We characterized the resulting poly(amide-imide)s by elemental analysis, thermal gravimetric analysis (DSC, TGA, and DTG), and FTIR spectroscopy, and by measuring their viscosities, specific rotations, and solubilities. All of the polymers were soluble at room temperature in polar solvents such as N ,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, tetrahydrofuran, and N-methyl-2-pyrrolidone.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.251-256
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• 2002

Fresh bamboo (Phyllostachys bambuoides sieb. et zucc.) was charred at the mechanical steel kiln and traditional earth kiln with subsequent condensation of its smoke to 10$0^{\circ}C$. It was settled down for 12 months to remove tar components and then the middle layer of the liquid was collected as a bamboo smoke distillates to analyze its chemical composition and physicochemical characteristics for use as food additives or processing aids. The gravity, transmittance, reflectivity, and viscosity were 1.008, 89.05%, 1.36%, and 12.48 cp in the bamboo smoke distillates processed by mechanical steel kiln (MBSD) and 1.012, 98.33%, 1.34% and 9.05 cp in the bamboo smoke distillates by traditional earth kiln (TBSD), respectively. The color of TSBD was brighter than that of MBSD. The pH and titratable acidity, tar and remains were 3.55 and 2.830%, 2.803% and 0.671%, respectively, in the MBSD and 2.93 and 3.470%, 0.051% and 0.004%, respectively, in the TBSD. The major phenolic compounds of bamboo smoke distillates (BSD) were phenol, Ο-cresol, p-cresol, and guaiacol and the major organic acids were acetic acid, propionic acid, iso-butyric acid, and n-butyric acid, and major alcohols were methanol, furfuryl alcohol, and maltol. The contents of phenolic compound and alcohol were more in MBSD than in TBSD whereas the content of organic acid was more in TBSD than in MBSD. Therefore, toxic compounds for the human body, such as methanol from BSD should be removed for use as a food ingredient in the future.

• Journal of the Korean Chemical Society
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• v.40 no.1
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• pp.81-86
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• 1996

The physical properties of epoxy molding compound (EMC) according to the change of softening point of epoxy resin have been investigated in order to study the relationship between the properties of o-cresol novolac epoxy resin, which is main component of EMC for semiconductor encapsulation, and EMC. The softening points of used epoxy resin are 65.1 $^{\circ}C$, 72.2 $^{\circ}C$, and 83.0 $^{\circ}C$, respectively. The flexural strength and flexural modulus as mechanical properties were measured, and thermal expansion coefficient, thermal conductivity and glass transition temperature (Tg) as thermal properties, and spiral flow as moldability have been investigated to see the change of physical properties of EMC. The flexural modulus, thermal expansion coefficients in the glass state (${\alpha}_1$), and thermal conductivity of EMC were found to be keep constant value irrespective of the change of softening point, but Tg increased with softening point of epoxy resin, and the spiral flow decreased with that. It can be considered that these phenomena are due to the increase of crosslinking density of EMC according to the increase of softening point. The transition points were found out in the thermal expansion coefficient data in the rubbery state (${\alpha}_2$) and the flexural strength data. These can show the decrease of filler dispersion according to increase of epoxy resin viscosity.