• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.11
• /
• pp.24-30
• /
• 2018

Various investigations of vegetable oil extracted from natural resources are underway because of their low cost and environmental value. On the other hand, the double bonds in vegetable oil should be substituted to other high reactive functional groups due to their low reactivity for synthesizing bio-polymeric materials. ${\alpha}$-eleostearic acid, which consists of a conjugated triene, is the main component of tung oil, and the conjugated triene allows tung oil to have higher reactivity than other vegetable oils. In this study, tung oil was copolymerized with styrene and divinylbenzene to make a thermoset resin without any substitution of functional groups. The thermal and mechanical properties were measured to examine the effects of the composition of each monomer on the synthesized thermoset resin. The results showed that the products have only one Tg, which means the synthesized thermoset resins are homogeneous at the molecular level. The mechanical properties show that tung oil acts as a soft segment in the copolymer and makes a more elastic product. On the other hand, divinylbenzene acts as a hard segment and makes a more brittle product.

• Journal of the Korean Applied Science and Technology
• /
• v.36 no.1
• /
• pp.348-354
• /
• 2019

Dipalmitoyl phosphatidyl choline(DPPC), Polyphenol Derivatives, and Hematoxylin-Eosin were directly sonicated in acidic condition for 6 minutes to give clear stock solutions. Absorbtion properties of Polyphenol Derivatives in lecithin vesicle of Diphalmitoyl phosphatidyl choline system at $25^{\circ}C$ have been studied by absorbtion spectroscopy. The equilibrium of Polyphenol Derivatives between monomer and dimer in lecithin vesicles have been existed at low concentration of Polyphenol Derivatives, but oligomer has been formed in vesicle at high concentration of lecithin vesicles. By adding Bacteriorhodopsin(BR) to constant concentration of Polyphenol Derivatives decreased the absorbtion ratio(${\alpha}/{\beta}$) of Polyphenol Derivatives was increased during phase transition of dipalmitoyl phosphatidyl choline. In the presence of column eluted lamella vesicle and mixture of uni- and multilamella aggregates. The differences of rate between column eluted- and mixture were observed, therefore column eluted lamella reaction was represented more catalytic effect. The phase transition temperature of hydrolysis on Dipalmitoyl phosphatidyl choline and Polyphenol Derivatives were measured higher than it of Dipalmitoyl phosphatidyl choline and no Polyphenol Derivatives.

• Journal of Ginseng Research
• /
• v.43 no.2
• /
• pp.186-195
• /
• 2019

Background: Notoginseng stem-leaf (NGL) ginsenosides have not been well used. To improve their utilization, the biotransformation of NGL ginsenosides was studied using ginsenosidase type-I from Aspergillus niger g.848. Methods: NGL ginsenosides were reacted with a crude enzyme in the RAT-5D bioreactor, and the dynamic changes of multi-ginsenosides of NGL were recognized by HPLC. The reaction products were separated using a silica gel column and identified by HPLC and NMR. Results: All the NGL ginsenosides are protopanaxadiol-type ginsenosides; the main ginsenoside contents are 27.1% Rb3, 15.7% C-Mx1, 13.8% Rc, 11.1% Fc, 7.10% Fa, 6.44% C-Mc, 5.08% Rb2, and 4.31% Rb1. In the reaction of NGL ginsenosides with crude enzyme, the main reaction of Rb3 and C-Mx1 occurred through Rb3${\rightarrow}$C-Mx1${\rightarrow}$C-Mx; when reacted for 1 h, Rb3 decreased from 27.1% to 9.82 %, C-Mx1 increased from 15.5% to 32.3%, C-Mx was produced to 6.46%, finally into C-Mx and a small amount of C-K. When reacted for 1.5 h, all the Rb1, Rd, and Gyp17 were completely reacted, and the reaction intermediate F2 was produced to 8.25%, finally into C-K. The main reaction of Rc (13.8%) occurred through Rc${\rightarrow}$C-Mc1${\rightarrow}$C-Mc${\rightarrow}$C-K. The enzyme barely hydrolyzed the terminal xyloside on 3-O- or 20-O-sugar-moiety of the substrate; therefore, 9.43 g C-Mx, 6.85 g C-K, 4.50 g R7, and 4.71 g Fc (hardly separating from the substrate) were obtained from 50 g NGL ginsenosides by the crude enzyme reaction. Conclusion: Four monomer ginsenosides were successfully produced and separated from NGL ginsenosides by the enzyme reaction.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.46 no.2
• /
• pp.165-172
• /
• 2019

The purpose of this study was to evaluate the effect of application time and phosphoric acid etching of 8th generation adhesives containing functional monomer on adhesive performance in primary teeth. 80 extracted non-carious human primary teeth were selected and divided into 8 groups based on 3 factors: (1) adhesive: G-Premio bond and Single bond universal; (2) application time: shortened time and manufacture's instruction; (3) acid etching mode: self-etching and total-etching. Shear bond strength was measured using a universal testing machine, and fractured surface were observed under scanning electron microscope. Microleakage was evaluated by dye penetration depth. G-Premio bond were not significant different in shear bond strength and microleakage depending on application time of adhesive and acid etching mode. In Single bond universal, shear bond strength of short application time was significantly lower than that of long adhesive application time (p = 0.014). Clinically applicable shear bond strength values (> 17 MPa) were identified in all groups. These results suggested that G-Premio bond be used clinically for a short application time without phosphoric acid etching.

• Applied Chemistry for Engineering
• /
• v.22 no.1
• /
• pp.37-44
• /
• 2011

The critical micelle concentration (CMC) of sorbitan laurate SP 20 surfactant in this paper was near $7.216{\times}10^{-4}mol/L$ and the surface tension at CMC was about 26.0 mN/m, which showed higher CMC and lower surface tension than those of octylphenol ethoxylate octylphenol ethoxylate (OPE) 10 surfactant. Dynamic surface tension measurement using a maximum bubble pressure tensiometer showed that the adsorption rate at the interface between air and surfactant solution was found to be slower with SP 20 surfactant, presumably due to a low mobility of SP 20 surfactant monomer. The contact angle of SP 20 surfactant solution was observed to decrease with an increase in surfactant concentration and showed a larger value than that of OPE 10 surfactant solution. Half-life time for foams generated with 1 wt% surfactant solution was also larger with SP 20 surfactant, which indicated higher foam stability with SP 20 surfactant. Dynamic behavior study reveals that the solubilization of n-decane oil was much lower with SP 20, which is in good agreement with experimental results of foam stability, contact angle and CMC. Dynamic interfacial tension measurement by a spinning drop tensiometer shows that interfacial tensions at equilibrium condition in both systems were almost the same but the time required to reach equilibrium was longer with SP 20.

• Applied Chemistry for Engineering
• /
• v.22 no.6
• /
• pp.623-626
• /
• 2011

Various poly(amic acid)s were synthesized from PMDA/BPDA/p-PDA/ODA with different mole ratios and effectively converted into 4-component polyimide films by thermal imidization. The chemical structures and thermo-mechanical properties of polyimide films were examined using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analyzer (TGA), thermo-mechanical analyzer (TMA), dynamic mechanical analyzer (DMA) and universal tensile machine (UTM). The tensile strength, modulus, and thermal properties of polyimides films increased with the amount of rigid PMDA and p-PDA, while the elongation and moisture absorption of polyimide films increased with the amount of flexible BPDA and ODA. One of 4-component polyimide films exhibited a similar coefficient of thermal expansion (CTE) value to that of copper when it was composed of PMDA : BPDA : p-PDA : ODA with the ratio of 5 : 5 : 4 : 6. Thus, this polyimide film could be useful for a base film for flexible copper clad laminates (FCCL) of flexible printed circuit boards.

• Membrane Journal
• /
• v.31 no.3
• /
• pp.212-218
• /
• 2021

It is inevitable to generate incomplete combustion gases when mankind utilizes fossil fuels. From this point of view, gas separation process of combustion gas suggests the possibility of recycling CO gas. In this study, we fabricated a facilitated transport polymeric composite membrane for CO separation using AgBF₄ and HBF₄. The copolymer was synthesized via free-radical polymerization of poly(vinyl alcohol) (PVA) as a main chain and acrylic acid (AA) monomer as a side chain. The polymer synthesis was confirmed by FT-IR and the interactions of graft copolymer with AgBF₄, and HBF₄ were characterized by TEM. PVA-g-PAA graft copolymer membranes showed good channels for facilitated CO transport. In this perspective, we suggest the novel approach in CO separation membrane area via combination of grafting and facilitated transport.

• Clean Technology
• /
• v.26 no.4
• /
• pp.311-320
• /
• 2020

In this study, the photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) was carried out under visible light irradiation using CdS and CdZnS/ZnO photocatalysts prepared by a simple precipitation method. This study focused on examining the effect of physicochemical properties of dye and photocatalyst on the reaction pathway of photocatalytic degradation. The prepared photocatalysts were characterized by XRD, UV-vis DRS and XPS. Both the CdS and CdZnS/ZnO photocatalysts exhibit an excellent absorption in the visible light and the UV light regions. It was observed that the photocatalytic degradation of MO proceeds via the same reaction mechanism on both the CdS and CdZnS/ZnO photocatalysts. However, the photocatalytic degradation of RhB and MB was found to proceed through a different reaction pathway on the CdS and CdZnS/ZnO catalysts. It is interesting to note that MB dimer was formed on the CdS catalyst at the beginning of the photocatalytic reaction, while the MB monomer was degraded during the overall photocatalytic reaction on CdZnS/ZnO. The above results may be mainly ascribed to the difference of band edge potential of the conduction band in the CdS and CdZnS/ZnO semiconductors and the adsorption property of dye on the catalysts.

• Journal of Navigation and Port Research
• /
• v.45 no.3
• /
• pp.109-116
• /
• 2021

The explosion of a chemical tanker ship during cargo transshipment via double-banking at Ulsan Port, resulted in major damage including fires involving nearby ships. As a follow-up measure to prevent the recurrence of similar accidents, the 'Safety Management of Dangerous Goods in Port' was established, and the designation of a transshipment pier for dangerous goods is required given the risk of explosion and the impact on major facilities in the port. This study evaluated the Fire & Explosion Index of major transshipment cargoes in Ulsan Port to design a transshipment pier based on the Explosion Risk Assessment. Based on the results of Fire & Explosion Index evaluation of styrene monomer and benzene, severe explosion risk was confirmed, and the exposure radius was calculated. Based on the results of the exposure radius, the risk range for each major pier was calculated, and 12 terminals were proposed as transshipment pier candidates considering port facilities, surrounding dangerous facilities, and residential aspects. Since the results of the study suggest transshipment piers based on the risk radius alone, maritime traffic safety, pier and mooring facilities, safety facilities and accessibility for emergency response should be considered comprehensively to designate actual transshipment piers.

• Clean Technology
• /
• v.15 no.3
• /
• pp.172-179
• /
• 2009

The thermoplastic polyurethane waste (TPU-S) with good tensile properties, hardness, NBS abrasion resistance, specific gravity and low wet coefficient of kinetic friction was melt-blended with ethylene propylene diene monomer rubber (EPDM) with high wet slip resistance and low mechanical properties to form EPDM/TPU-S blend films, and their composition-property relationship was investigated to find the optimum composition for shoe outsole material. The properties except the wet slip resistance increased with increasing TPU-S contents in the blend. All the properties except elongation at break, specific gravity and the wet coefficient of kinetic friction in the range of $0{\sim}65\;wt%$ of TPU-S did not attain the values predicted by the simple additive rule. The optimum weight ratio of EPDM/TPU-S for the application to the typical shoe outsole material was found to be 30/70.