• Journal of Conservation Science
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• v.27 no.2
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• pp.191-199
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• 2011

A study was done to compare the properties of artificially deteriorated silk with ultraviolets for reinforcing of loss area of paintings on silk. Deteriorated surface of raw silk irradiated by long-wavelength ultraviolet(UV-A) than short-wavelength ultraviolet(UV-C) was similar to naturally aged raw silk. UV-A irradiation raw silk was slowly decreased in tensile tenacity and elongation and lowered in yellowness index than that of UV-C. Water content of UV-A irradiation raw silk than that of UV-C was higher. UV-A irradiation raw silk had no problem in dyeing and inpainting for conservation because of low yellowness index. UV-C irradiation raw silk was brittle, but UV-A irradiation raw silk was seemed to tough and similar to naturally aged raw silk. Korean painting conservator estimated that UV-A irradiation raw silk was more proper for reinforcing of loss area of paintings on silk than that of UV-C.

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.602-606
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• 2014

In this study, we observed changes in the physical properties of norbornene dialkyl ester applied to a PVC. The PVC specimens were prepared by blending PVC, norbornene dialkyl ester and stabilizers. Then, the hardness, tensile strength, elongation, tearing strength, transmittancy, haze and yellowness index of these specimens were measured, and were compared with DOP. The hardness of compounds except dicyclohexyl-5-norbornene-2,3-dicarboxylate (DCHN) were an equal to or higher than that of DOP. The tearing strength and tensile characteristic of DCHN could not be analyzed due to its high hardness. Tensile properties such as the tensile strength and elongation were improved for six compounds except diisononyl-5-norbornene-2,3-dicarboxylate (DINN). All compounds measured showed better tearing strength and transmittancy than those of DOP. Also all norbornene derivatives except DDN showed good haze indices. The yellowness index of DON and DPN showed similar values as DOP.

• Polymer(Korea)
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• v.26 no.4
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• pp.452-461
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• 2002

In this study, the effect of various concentrations of antioxidants on thermo-oxidative degradation of polyamide 6 was investigated. Unstabilized and stabilized polyamides 6 were subjected to long-term oven aging in ambient atmosphere at 70~$160^{\circ}C$. All of specimens were discolored within 100 hr at temperature range of 70~$160^{\circ}C$. Optimum antioxidant concentration was determined from the data of mechanical properties, yellowness index and relative viscosity. The synergistic effect of each primary and secondary antioxidant concentrations was not observed. Yellowing phenomenon was explained by using NMR, IR and EA. Different carbonyl groups were detected by $^{13}C$/NMR. During thermooxidative degradation, oxygen consumptions were determined by EA. The lifetime after long-term aging was predicted using Arrhenius equation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.1
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• pp.47-53
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• 1980

Of 1, 428 entries examined to locate gene sources resistant to Septoria brown spot from the Korean native soybean collection, most lines were evaluated as highly susceptible, showing numerous leaf spots with surrounding yellowing tissue, while 136 lines of the entries showed the leaf spots without the yellowing. However, leaf defoliation was so much higher in inoculated soybean plants than those of uninoculated, regardless of leaf yellowing that resistance to Septoria brown spot could not be characterized by the lesion type. Various yield composing characters were negatively correlated to the leaf defoliation, suggesting that early defoliation incited by Septoria brown spot might result in significant yield reduction in soybean.

• Polymer(Korea)
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• v.29 no.3
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• pp.237-241
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• 2005

Photocurable pentaerythritol modified hyperbranched acrylates were prepared from trimellitic anhydride, glycidyl methacrylate and pentaerythritol derivatives. Thermal stability obtained by using TGA showed that HBMA-1 was superior to the others. Hardness, abrasion resistance and tensile strength of HBMA-1 showed that Hey were also superior to the others. Value of yellow index of HBMA-1 showed the lowest.

• Applied Chemistry for Engineering
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• v.16 no.3
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• pp.342-347
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• 2005

Photocurable hyperbranched acrylates were prepared from acrylic acid and hyperbranched polyol (HBP-16, 32, 64). Physical properties of three kinds of photocurable hyperbranched acrylated were investigated. Thermal stability of UV cured film measured by TGA shifted to higher temperature with increasing of functionality. Hardness, abrasion resistance, and tensile strength of UV cured film also increased with increasing functionality of acrylate. Weathering test for UV cured film showed the value of yellow index increased with increasing functionality of acrylate.

• Applied Chemistry for Engineering
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• v.16 no.1
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• pp.101-106
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• 2005

Photocurable modified 6 functional polyacrylate(PA-1) were prepared from dipentaerythritol derivatives (DPET) and acrylic acid, and 12 functional polymethacrylate(PA-2) were prepared from dipentaerythritol derivatives (DPET), trimellitic anhydride, and glycidyl methacrylate. And physical properties of photocurable modified poly(meth)acrylate were increased with increasing functionality of (meth)acrylate. Thermal stability of UV cured film obtained by using TGA was shifted to higher temperature as the increasing of functionality. Hardness, abrasion resistance and tensile strength of UV cured film were increased with increasing functionality of (meth)acrylate. Values of yellow index were increased with increasing functionality of (meth)acrylate.

• Polymer(Korea)
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• v.24 no.1
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• pp.72-81
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• 2000

Benzoic acid polyester/lactone polyol were synthesized by polycaprolactone 0201 as diol, trimethylolpropane as triol, adipic acid as dibasic acid, and benzoic acid as monobasic acid. Polyisocyanate prepolymer Desmodur N-100 of HDI-biuret type was used in this study. Two-component polyurethane coatings were prepared by blending benzoic acid polyester/polycaprolactone, polyisocyanate, wetting/dispersing agent, white pigment, and flowing agent. Various properties were examined on the film coated with the prepared polyurethane. They showed excellent physical properties such as abrasion resistance, accelerated weathering resistance, and yellowness index. They also showed good physical properties such as flexibility, impact resistance, 60$^{\circ}$ specular gloss, cross hatch adhesion, hydrocarbon resistance, and lightness index difference. Hardness of coating showed a little poor character. The introduction of polycaprolactone 0201 as diol in the polyurethane coatings improved the hydrocarbon resistance, impact resistance, and flexibility of coatings. According to the drying and curing behavior with the contents of benzoic acid, they seem to have reasonable coating properties such as drying time of 2 to 4 hours and pot-life time of 20 to 37 hours.

• Polymer(Korea)
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• v.28 no.6
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• pp.531-537
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• 2004

Various half-ester acrylates were prepared from anhydrides and 2-hydroxyethyl acrylate. Photocurable epoxy modified acrylates were prepared from synthesized half-ester acrylate and neopentylglycol diglycidylether. Physical properties such as hardness, yellowing, tensile strength and elongation were tested and compared as the structure of oligomer in cured-film differs. It was found that viscosity of neopentylglycol diglycidylether-hexahydrophthalic anhydride (NP-HA) was highest. Hardness and tensile strength of photocrosslinked neopentylglycol diglycidylether-hexahydrophthalic anhydride were better than those of other photocrosslinted epoxy acrylates. And 5% weight loss temperature of photocrosslinked neopentylglycol diglycidylether-hexahydrophthalic anhydride was higher than those of other photocrosslinked epoxy acrylates. Value of yellow index of photocrosslinked neopentylglycol diglycidyl ether-succinic anhydride (NP-SA) was lower than the other products.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.34 no.2
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• pp.204-210
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• 1989

Normally cultured, harvested and yellowed leaves of aromatic tobacco variety. KA 101 were sun-cured under conventional polyethylene film house, air-cured in burley curing barn, and bulk-cured at three temperatures of 40$^{\circ}C$, 50$^{\circ}C$ and 60$^{\circ}C$. respectively, to investigate the effects of curing conditions on quality and chemical properties of leaf tobacco. Air-cured leaves had the poorest quality by price with little difference between that of sun-cured and three bulk-cured ones. Air-cured leaves were higher in ammonia nitrogen, protein nitrogen, total nitrogen, ash content and pH, but lower in sugar content when it compared with those of sun-cured and three bulk-cured ones. The curing variables tested did not affect the content of pet. ether ext. and volatile organic acids. The content of pet. ether ext., volatile organic acids, and most of volatile neutrals tended to decrease or not to change as the bulk-curing temperature increased. A quality index, (volatile organic acids, mg/l00g+％ pet. ether ext.) / ％(ash+pH) x 10, was found to be most accurate and easy to apply for the quality evaluation of aromatic tobaccos.