• Elastomers and Composites
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• v.52 no.3
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• pp.201-210
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• 2017

We studied the antibacterial effect and mechanical properties of PLA composites with in organic porous zeolite-type bacteriocides. The specimens were prepared by an intermeshing co-rotating twin screw extruder using different contents of inorganic bacteriocide. The degree of dispersion of the in organic bacteriocide in the PLA composite was confirmed by FE-SEM. The contents of Ag and Zn in the composite were also investigated by energy dispersive spectroscopy at different concentrations of the inorganic bacteriocide. The antibacterial effects were analyzed by turbidity analysis, shaking culture, and drop-test. The mechanical properties, such as the tensile and flexural properties, impact strength, and physical properties, were also investigated. As the content of inorganic bacteriocide increased, the antibacterial activity was increased, especially against Staphylococcus aureus. Mechanical properties, namely, tensile strength, elongation, flexural strength, and impact strength, tended to decrease with an increase in inorganic bacteriocide content, but the tensile and flexural modulus increased.

• Elastomers and Composites
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• v.39 no.4
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• pp.286-293
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• 2004

Ester- and ether-based thermoplastic polyurethanes of different hardness were injection molded at different mold temperatures and effects of mold temperature on the physical properties of TPUs were investigated. Glass transition temperatures of soft segments of TPUs were hardly changed by mold temperatures. The phase separation of soft and hard segments of injection molded TPUs were affected little by mold temperatures. However, crystallinity of hard segments, temperature range of rubbery plateau, and tensile strength of injection molded TPUs decreased with increasing mold temperatures for TPUs of high hardness. However, injection molded TPUs of low hardness showed increases of crystallinity of hard segments, temperature range of rubbery plateau, and tensile strength with increasing mold temperatures. Different physical properties of injection molded TPUs depending on mold temperatures were attributed to different crystallization and physical crosslinking effects of hard segments.

• Proceedings of the Korean Fiber Society Conference
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• 1998.10a
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• pp.33-36
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• 1998

Segmented block copolyetheresters defined as copolymers having sequences of alternating polyester hard blocks and polyether soft blocks create labile physical cross-links upon crystallization of hard polyester blocks Since the nature of the physical interlocking is a crystallite formed exclusively from the crystallizable hard segment, the hard segment content (HSC) and hard segment length (HSL) will play an important role in determining the properties such as mechanical property and dynamic mechanical property. (omitted)

• Corrosion Science and Technology
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• v.7 no.5
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• pp.269-273
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• 2008

It is known that the fluoric resin has the most outstanding properties in the extremely acidic environment of high temperature. However, this resin is the thermal hardening type that needs long time heat treatments above $250^{\circ}C$. It's impossible to use in situ in the extremely acidic environment such as a huge FGD ductworks or industrial chemical tanks. Furthermore, even the natural hardening type fluoric coatings which can be hardened less than $120^{\circ}C$ can not be applied to the highly acidic environmental plants because of its chemical resistance. In this study, new fluoric coatings that has excellent thermal resistance, chemical resistance and corrosion resistance has been developed in order to solve above problems and to be applied to the large plant structures in the field. These newly developed coatings are organic and inorganic composite type that have fluoric rubber(100 wt%), fluoric resin(5~50 wt%), oxalates(5~30 wt%), inorganic fillers mixed with plate-type and bulk-type solids(20~150 wt%), hardeners(0.5~5 wt%), and hardening hasteners(0.1~3 wt%). The best chemical and physical properties of these coatings are acquired by variation of adhesive reinforcement agents, dispersants, leveling agents. Mixing ratios of plate-type and bulk-type inorganic fillers influence the thermal properties, abrasive resistance and chemical infiltration properties of coatings. The mixing control is also very important to have homogeneous surface and removing inner voids of coatings.

• Bulletin of the Korean Chemical Society
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• v.26 no.2
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• pp.292-296
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• 2005

Physical and chemical properties of thexylboronic acid and its derivatives such as thexylboroxine and ethylene glycol or diethanolamine thexylboronic ester have been studied. Thexylboronic acid can be extracted from an organic solution with an aqueous sodium hydroxide solution as an “te”complex. It is readily converted into thexylboroxine in the presence of anhydrous magnesium sulfate in pentane. It reacts with simple alcohols only slowly; however, it reacts readily with excess diethanolamine in the presence of anhydrous magnesium sulfate to give the corresponding ester.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.266-272
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• 2009

Physical and chemical properties of waste LCD glass were investigated to test the feasibility of feed materials for the production of foamed glass. For this study, chemical analysis, thermal analysis, rheological consideration with the viscosity change under high temperature and thermal expansion coefficient were carried out and the trial production of foamed glass as; in spherical and block type also attempted. All results showed waste LCD glass would be a good feed material for the production of foamed glass and foaming technology of LCD glass would be an effective recycling alternative.

• Polymer(Korea)
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• v.31 no.2
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• pp.105-110
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• 2007

We investigated resin, thinner, painting, and injection for analyzing the chemical effect of polymer, and made the optimum solution with the best performance of ABS (acrylonitrile butadiene styrene) resin. The effect depended on chemical material especially its chemical and physical properties instead of mechanical transformation. When we looked over ABS resin, injection, chemical material and painting, we found out thinner was the main factor for painting problem. Throughout this test, we could solve the problem, secure the system for control process and drop many factors for changing quality.

• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.259-264
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• 2016

In this study, we applied six different norbornene dialkyl esters as a plasticizer to an isoprene rubber (IR) and evaluated replaceability of DEHP which is an endocrine disruptor. IR test sheets were prepared by blending IR, norbornene dialkyl ester, vulcanizing agent, etc. and processing properties of the IR were evaluated by measuring Toque, scorch time, cure time and mooney viscosity. Mechanical properties of IR test sheet including hardness, tensile strength, 100% modulus and elongation were also measured and the physical properties of norbornene dialkyl ester applied as a plasticizer were compared to those using DEHN. Both the maximum and minimum toque for the norbornene dialkyl ester as a plasticizer were similar to those of using DEHP. In addition, the scorch and cure time of the former were slightly longer than those of the latter. The mooney viscosity for the case of DEHN was slightly lower than that of the latter. DEHN was also superior to DEHP in terms of processing. The hardness and thermal properties of all IR test sheets were measured to be similar to each other. The linear alkyl chain of norbornene compounds also exhibited good tensile characteristics.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.592-598
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• 1999

Exterior finishing materials of artificial stones are manufactured with the mixture of water, cement, stone powder and light-weight aggregate. In this research, we tried to find a way of increasing the physical properties and decreasing the manufacturing cost of artificial stone. So, we used ${\beta}$-NSF base surfactant and vinsol base surfactant to the artificial stone mixture instead of light-weight aggregate. The optimum dosage of the ${\beta}$-NSF and vinsol surfactants for artificial stone are found to be 1.0 wt % of cement, respectively. The physical properties increased ca. 20% and the durability for freezing & thawing of the new artificial stone increased ca. 300%. While the manufacturing cost of the new artificial stone decreased as much as 30%.

• Environmental Analysis Health and Toxicology
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• v.20 no.4 s.51
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• pp.259-271
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• 2005

Engineered nanoparticles exhibit a variety of unique and tunable chemical and physical properties. These unique properties make the nanoparticles central components and widespread potential applications in nanoindustry. However, the potential toxicities of nanoparticles have not been fully evaluated. Recently, the impacts of nanoparticles to human and environment became the emerging issue of toxicology. In this article, physicochemical properties and toxicities of carbon nanotube, fullerene, quantum dots, and other types of nanomaterials were reviewed and the strategy of risk assessment were suggested based on the frame of chemical assessment.