• Elastomers and Composites
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• v.54 no.3
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• pp.232-240
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• 2019

A superabsorbent hydrogel (SAH) can absorb and retain water weighing more than a hundred times of their dry weight because of their three-dimensional hydrophilic structure. To fabricate an SAH, itaconic acid (IA) and vinyl sulfonic acid (VSA) were subjected to radical polymerization in an aqueous solution, wherein IA and VSA were neutralized, and then, a crosslinker and a thermal initiator were added in sequence. The structure of poly(IA-co-VSA) was characterized using attenuated total reflectance Fourier-transform infrared spectroscopy. We also studied the changes in the absorption properties of the SAH composites according to the polymerization temperature, degree of neutralization, type and content of the initiator used, and type and content of the crosslinker used. Thus, we could determine the effects of some synthetic factors on the absorption properties of the SAH.

• Elastomers and Composites
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• v.49 no.3
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• pp.232-238
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• 2014

Solution polymerization was conducted with water-soluble acrylic acid (AA) as a monomer and potassium persulfate (KPS) as an initiator at a selected temperature between $60^{\circ}C$ and $90^{\circ}C$ with water as a reaction medium. When the ratio between AA and water was reduced or initiator concentration increased, molecular weights decreased. An increase in the reaction temperature produced lower molecular weights. The polydispersity index was close to 1.5 in most of the reactions. An increase in the stirring speed up to 400 rpm led to a progressive increase in molecular weights. When the stirring speed reached 800 rpm, however, we found that both the number and weight average molecular weights decreased. The glass transition temperature was nearly independent of moelcular weights and determined to be between $113^{\circ}C$ and $116^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.4
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• pp.581-586
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• 1998

The present study was conducted to prepare seaweed extracts suppressing mutagenic activity of 2-amino-1-methyl-6-phenylimidazo[4,5-b] pyridine ( PhIP ) ana 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx) derived from cooked meat produce. The tumor initiation activity of PhIP and MeIQx was assayed with Ames method using Salmonella typhimurium TA98 in the presence of S-9 mixtures before and after addition of methanol-solubles of seaweed, such as, Phaeophyta; Undaria pinnatifida, Ecklonia stolonifera Ecklonia cava, Laminaia japonica Sargassum fulvellum, Sargassum hornezi, Sargassum miyabei, Sargassum thunbergii, Agarum cribrosum and Hizikia fusifomis, Rhodophpei Porphyra yezoensis, Grateloupia eiliptiut Lomentraria catenata, Ploemium telfairiae and Glarilaria verrucosa, Chlorophyta; Codium fragile, Enteromorpha compresa and Ulva pertusa. Among seaweed tested, Phaeophyta was shown the higher desmutagenic activity than Rhodophyta and Chlorophyta. E. stolonifera, E. cava and S. miyabei, among Phaeophyta exerted the stronger desmutagenic activity (above $90\%$/2 mg). The ethyl acetate, diethyl ether and chlomform extracts except water extracts from E. stolonifera exhibited a high desmutagenic activity. The ethyl acetate extract of E. stolonifera which showed highest activity was fractionated with Sephadex LH20 column chromatography to give active fraction A-7, which showed desmutagenicity of $90\%$/mg against PhIP and $80\%$/mg against MeIQx. The active fraction had the absorbance at 207.7 and 232nm.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.40-46
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• 2020

Tertbutylperoxymaleate is the one of the organic peroxides used as a raw material of initiator formulations of artificial marble manufacturing. In this study, the thermal decomposition characteristic of TBPM was evaluated using the differential scanning calorimeter in the air and nitrogen circumstance. Regardless of the reaction atmosphere, TBPM showed the exothermic peak due to the drastic decomposition reaction below 130 ℃. The activation energy estimated by dynamic methods had a range of 203~217 kJ/mol and that estimated by model-free analysis method had a range of 118~232 kJ/mol with a thermal conversion. And the ADT₂₄, the temperature that lead to the maximum heating rate within 24 hours, was evaluated as (80~95) ℃ using the estimated activation energy.