• Journal of the Korean Wood Science and Technology
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• v.36 no.5
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• pp.42-48
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• 2008

This study was conducted to discuss the effects of hardener and extender contents on peak temperature, reaction enthalpy (${\Delta}H$), gelation time, viscosity change, and pH value in three types of UMF (urea-melamine- formaldehyde) resin with the help of perpHecT LogR meter, differential scanning calorimetry (DSC), and advanced rheometric expansion system (ARES), The results indicated that the pH value of Control A steeply decreased to 5,2 in the early stage but relatively remained constant thereafter as in Synthesis 1 and Synthesis 2, The peak temperature and time decreased as well, whereas ${\Delta}H$ and viscosity increased with the increase of hardener content. On the other hand, ${\Delta}H$ was not changed up to the extender content of 5% and then decreased with its further addition, And the pH value and peak temperature showed no change with the increase of extender content at the hardener content of 5% in three types of UMF resin, The effect of hardener content in this experiment, however, appeared more conspicuous in Control A than in the other two types of Synthesis 1 and Synthesis 2, These results might be caused by higher molecular weight with longer chains of methylene ($-CH_2-$) and methylene ($-CH_2-O-CH_2-$) ether bridges or much more branched chains in Control A.

• Journal of Powder Materials
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• v.23 no.6
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• pp.414-419
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• 2016

Much attention has been paid to thermally conductive materials for efficient heat dissipation of electronic devices to maintain their functionality and to support lifetime span. Hexagonal boron nitride (h-BN), which has a high thermal conductivity, is one of the most suitable materials for thermally conductive composites. In this study, we synthesize h-BN nanocrystals by pyrolysis of cost-effective precursors, boric acid, and melamine. Through pyrolysis at $900^{\circ}C$ and subsequent annealing at $1500^{\circ}C$, h-BN nanoparticles with diameters of ~80 nm are synthesized. We demonstrate that the addition of small amounts of Eu-containing salts during the preparation of melamine borate precursors significantly enhanced the crystallinity of h-BN. In particular, addition of Eu assists the growth of h-BN nanoplatelets with diameters up to ~200 nm. Polymer composites containing both spherical $Al_2O_3$ (70 vol%) and Eu-doped h-BN nanoparticles (4 vol%) show an enhanced thermal conductivity (${\lambda}{\sim}1.72W/mK$), which is larger than the thermal conductivity of polymer composites containing spherical $Al_2O_3$ (70 vol%) as the sole fillers (${\lambda}{\sim}1.48W/mK$).

• Journal of the Microelectronics and Packaging Society
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• v.14 no.1
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• pp.27-31
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• 2007

The cpapcitors with MIM(metal-insulator-metal) structures using PVP gate insulation films were prepared for the application of flexible organic thin film transistors (OTFT). The co-polymer organic insulation films were synthesized by using PVP(poly-4-vinylphenol) as a solute and PGMEA(propylene glycol monomethyl ether acetate) as a solvent. The cross-linked PVP insulation films were also prepared by addition of poly(melamine-co-formaldehyde) as thermal hardener. The leakage current of the cross- linked PVP films was found to be about 1.3 nA on Al/PES(polyethersulfone) substrate, whereas, on ITO/ glass substrate was about 27.5 nA indicating improvement of the leakage current at Al/PES substrates. Also, the capacitances of all prepared samples on ITO/glass and Al/PES substrates w ere ranged from 1.0 to $1.2nF/cm^2$, showing very similar result with the calculated capacitance values.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.5
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• pp.36-42
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• 2019

In this study, the pre-treatment of lyocell fabrics was performed using phosphoric acid (PA) as a phosphorus flame retardant and melamine resin (MR) as a cross-linking agent to fabricate carbon fabrics using lyocell fibers. The physical and chemical changes were investigated by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD) and weight analysis. We confirmed that the weight yield of the carbon fabrics compared to the untreated fabrics increased by 14.7%, and width and length yield of the fabrics increased by 15% and 15.5%, respectively. This may be due to the effect of promoting the dehydration reaction of cellulose, forming char on the fiber surface, which induces a crosslinking reaction in the cellulose molecule and stabilizes the structure upon pyrolysis.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.31-36
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• 2019

Concrete is a material generally used to build structures and it is exposed to various environment conditions. In particular, a medium such as water lets noxious factors flow into concrete, causing a lot of damage. Therefore, different kinds of materials are being developed to increase the durability of concrete. Among such materials, silane and siloxane compound are known to have a high utilization as an absorption inhibitor. However, if aged or deteriorated reinforced concrete is treated with those compounds, they easily come off the concrete and lose their function since the basic material is weak. This study conducted an experiment to provide concrete with both an absorption-inhibiting effect and surface strengthening by using melamine-formaldehyde resins that are surface-treated with siloxane compound. In addition, a study on the porosity and surface hardness characteristics of a concrete was conducted to check the absorption-inhibiting effect and surface strengthening.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.915-920
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• 2018

With the development of modern microelectronics technologies, the power density of electronic devices is rapidly increasing, due to the miniaturization or integration of device elements which operate at high frequency, high power conditions. Resulting thermal problems are known to cause power leakage, device failure and deteriorated performance. To relieve heat accumulation at the interface between chips and heat sinks, thermal interface materials (TIMs) must provide efficient heat transport in the through-plane direction. We report on the enhanced thermal conduction of $Al_2O_3-based$ polymer composites, fabricated by the surface wetting and texturing of thermally conductive hexagonal boron nitride(h-BN) nanoplatelets with large anisotropy in morphology and physical properties. The thermally conductive polymer composites were prepared with hybrid fillers of $Al_2O_3$ macro beads and surface modified h-BN nanoplatelets. Hexagonal boron nitride (h-BN) has high thermal conductivity and is one of the most suitable materials for thermally conductive polymer composites, which protect electronic devices by efficient heat dissipation. In this study, we synthesized hexagonal boron nitride nanoparticles by the pyrolysis of cost effective precursors, boric acid and melamine. Through pyrolysis at $900^{\circ}C$ and subsequent annealing at $1500^{\circ}C$, hexagonal boron nitride nanoparticles with diameters of ca. 50nm were synthesized. We demonstrate that the addition of a small amount of calcium fluoride ($CaF_2$) during the preparation of the melamine borate adduct significantly enhanced the crystallinity of the h-BN and assisted the growth of nanoplatelets up to 100nm in diameters. The addition of a small amount of h-BN enhanced the thermal conductivity of the $Al_2O_3-based$ polymer composites, from 1.45W/mK to 2.33 W/mK.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.27 no.3
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• pp.141-147
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• 2021

The foreign trends of noncompliance occurring frequently in food contact materials during the period of 2011-2019 was investigated by analyzing the food safety risk information DB in the National Food Safety Information Service (NFSI). A total of 2,042 cases of noncompliance of food utensils, containers, and packages were classified into 5 violation categories; administrative procedures, manufacturing and processing standards, residues and migration standards, labeling and advertising, and quality standards. This was again subcategorized according to non-compliance causative factors. The non-compliances in residues and migration standards comprised the largest proportion (76.4%) of the violative categories. The number of noncompliance information collected in 2011 was 88 cases and increased to 373 cases in 2019. A 72.8% of the non-compliance case was identified to be products of 4 countries (China 64.2%, Germany 4.0%, Japan 3.2%, and Taiwan 3.1%), those produce large quantities of containers and packaging products. During the period of 2011-2019, the number of illegal use of hazardous materials and illegal recycling of waste synthetic resins has decreased to less than one a year since 2014. On the other hand, after 2016, inconsistency of heat-resisting temperature labeling (Taiwan), non-compliance in paper container's strength standards, violation of printing standards, and the risk of consumer injury while using the products were newly reported due to the strengthening of consumer safety protection regulations. Migration of hazardous substances in synthetic polymer products such as heavy metals, melamine and formaldehyde in melamine tableware, primary aromatic amines which are colorant components in kitchenware such as ladles and spatulas, and phthalate plasticizers have been continuously reported with high frequency.

• Journal of Advanced Technology Convergence
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• v.1 no.1
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• pp.7-13
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• 2022

In this study, we prepared the functionalized Shampoo with three-type functionalized microcaples which were synthesized by microcapsulation, respectively. In detail, the functionalized microcapsule was included such as (1) the functionalized microcapsule with core-menthol and shell-melamine resin and (2) the functionalized microcapsule with core-menthol and shell-lecithin, and (3) the functionalized microcapsule with core-cinnamon oil and shell-lecithin, respectively. The size and morphology of the prepared microcapsules was evaluated via Optical Microscopy (OM), Scanning Electron Microscopy (SEM) and Dynamic Light Scattering (DLS). From these results, the prepared microcapsules with size of 0.1~0.2 ㎛ and spherical morphology was confirmed. Furthermore, we applied the prepared Shampoo to treat hair. As results we confirmed that the scalp temperature was decreased about 3~4 ℃ compared to no treatment. This result may be considered that the core compounds are vaporize when the functionalized Shampoo is treated on scalp. We will determine the change of scalp pore, diameter of hair, and etc during treatment of the functionalized Shampoo.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.31-33
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• 2008

The study related that Red Phosphorus is surface coated by Al(OH)$_3$ using the proportion 1:1, 1:3, 1:5 respectively, and then take the coated red phosphorus as the core material, at the same time, use Melamine-Formaldehyde resin as the capsule materials for microcapsule processing. According to the TG analysis, the coated red phosphorus with the proportion 1:3 has the tiptop temperature of thermal decomposition, it reaches 376.20^{\circ}C$$. The same to the ratio of burning incomplete carbon it reaches 26.5%. The lowest moisture absorption ratio of the red phosphorus that used coated red phosphorus for microcapsule processing can reach 0.5% with the condition that thermal decomposition temperature decline 3.6%.

• Journal of the Korea Concrete Institute
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• v.11 no.6
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• pp.69-78
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• 1999

Hydroxyethyl cellulose -based-viscosity modifying admixture and melamine-basd-superplasticizer were selected to be admixtures for self-compacting concrete based on the test results of fluidity and air content of mortar using 3 different viscosity modifying admixtures. The experimental results show that the initial and final set of self-compacting concrete and fly ash concrete with viscosity modifying admixture only have been delayed approximately 5 hours and 8~9 hours, respectively. It is found that the optimum dosage of viscosity modifying admixtures, coarse aggregate and cement content are 0.2% of water content, under 742 kg/$\textrm{m}^3$ and over 364 kg/$\textrm{m}^3$, respectively. Test results also show that the optimum fly ash in replacement of cement is 10% of cement weight for the enhancement of fluidity and long-term strength.