• Journal of the Korean Society of Safety
• /
• v.21 no.1 s.73
• /
• pp.79-85
• /
• 2006

Olefinic compatibilized blend(R-PP/R-PE)/layered silicate composites have been prepared by melt intercalation technique directed from $Na^{+}$ montmorillonite(MMT) or organophilic montmorillonites while using magnesium hydroxide as flame retardant. Morphology and flammability properties were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM), thermogravimetry analysis(TGA), limiting oxygen index(LOI), UL94 test. It is found that the compatibilized blend/layered silicate(Cloisite 20A) nanocomposites have a mixed immiscible-intercalated structure and there is better intercalation when a compatibilizer is combined with the polymer and layered silicate to be melt blended. A very large increase in the LOI value was observed with hybrid filler addition and further enhancement in thermal stability and compatibility of blend was obtained for the compatibilized blend containing small amount of layered silicate.

• Carbon letters
• /
• v.8 no.1
• /
• pp.17-24
• /
• 2007

Microporous carbons with narrow pore size distribution have been successfully synthesized by using hydrolyzed and calcined silica as templates and phenol formaldehyde (pf) resin as carbon precursor. Phenol formaldehyde-silica micro composites were prepared by solution route. Subsesequently, silica templates were removed by HF leaching. Resulting carbons were steam activated. The porous carbons were characterized by nitrogen adsorption-desorption isotherm, SEM, FTIR analysis, iodine adsorption, thermogravimetry analysis, etc. Adsorption isotherms show that the porous carbon prepared from calcined silica as templates are microporous with 88% pores of size <2 nm porosity and are of type I isotherm, while porous carbon prepared by using hydrolyzed silica are microporous with 89% microporosity, shows hysteresis loop at high relative pressure indicating the presence of some mesoporosity in samples. The microporosity in porous carbon materials has a bearing on the nature of silica templates used for pore formation.

• Bulletin of the Korean Chemical Society
• /
• v.23 no.7
• /
• pp.964-970
• /
• 2002

We synthesized three kinds of chromophores incorporating aromatic quinoline unit as a $\pi-conjugated$ bridge in order to prepare more thermally stable nonlinear optical (NLO) chromophores than general stilbene unit. The NLO poly(methylmethacrylate) copolymer, polyimides, and polyester were successfully synthesized by these corresponding quinoline-based monomers. Their physical and optical properties were investigated by thermogravimetry, gel permeation chromatography, ultraviolet-visible spectroscopy, second harmonic generation (SHG) and electro-optic (EO) measurement. All the polymers exhibited better thermal stability,however their NLO activity was a little lower than that of general stilbene-based NLO polymers. Among three kinds of polymers, the PMMA copolymer with quinoline chromophores had the largest SHG coefficient d33 value of 27 pm/V (at 1.064 $\mu\textrm{m})$ and EO coefficient r33 value of 6.8 pm/V (at 1.3 $\mu\textrm{m}$).

• Elastomers and Composites
• /
• v.23 no.3
• /
• pp.213-222
• /
• 1988

The thermal decomposition of poly(n-butyl methacrylate)(Pn-BMA) was studied using a dynamic and isothermal thermogravimetry in nitrogen gas with 50ml/min at several heating rates from 1 to $20^{\circ}C/min$, and at several heating temperature from 320 to $370^{\circ}C$. The mathematical techniques used for calculation of activation energy were Kissinger, Anderson, Chatterjee-Conrad, Friedman, Fuoss, Ozawa and isolthermal method. The range of activation energies obtained using the several techniques was between 43 and 51Kcal/mol except Chatterjee-Conrad and this range agreed with each other very well. The thermal degradation of Pn-BMA was considered to be carried out by main chain scission.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.50.1-50.1
• /
• 2009

셀룰로오스를 Ca(OH)2와 Ni(OH)2를 Pot에 넣고 동시에 밀링 공정을 실시한 후, 열을 가함으로써 수소를 얻었다. X-ray diffraction (XRD), thermogravimetry/ mass spectrometry (TG/MS), gas chromatography (GC) 장비를 이용해 수소 발생량 및 촉매의 역할에 관하여 실험하였다. 촉매 Ni(OH)2를 대신한 NiO 또는 Ni를 사용했을 경우 사용된 촉매에 따른 수소의 발생량의 차이를 보였는데 이는 촉매의 사이즈가 수소 발생량과 관련이 있음을 보여주었다. 한편, Ca(OH)2를 대신하여 Li(OH)를 사용하였을 때 수소 발생 온도가 약$400\sim500\;^{\circ}C$ 범위에서 $350\sim400\;^{\circ}C$의 범위로 낮아져 보다 낮은 온도에서 수소 회수가 가능하였다. 이때 발생한 CO와 CO2는 수 ppm정도로 적은 양이었다.

• Journal of the Korea Institute of Building Construction
• /
• v.11 no.5
• /
• pp.515-522
• /
• 2011

As Construction and Demolition (C&D) debris increases every year, systems have been adopted to compel the use of recycled aggregate made from C&D debris, and the use of recycled aggregate in the construction field has increased. But environmental problems linked to the alkalinity of recycled aggregate have occurred, and a study on approaches to lower the alkalinity of recycled aggregate is needed. It was certified by this study that a large amount of recycled aggregate could be carbonated in the C&D debris midterm-treatment field. As a result, the density and the water absorption of recycled aggregate after carbonation reaction was improved, and pH of recycled aggregate was lowered from over 11 to 9.4. X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Thermogravimetry/Differential Thermal Analysis (TG/DTA) methods also indicated the carbonation of recycled aggregate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2005.07a
• /
• pp.361-362
• /
• 2005

Antimony doped tin oxide(ATO) nano powders have been synthesized by homogeneous precipitation method using $SnCl_4\cdot5H_2O$ for precursor, $SbCl_3$ as doped material and urea. The hydrolysis of urea and conductive mechanism and Heat treatment was performed at the temperature from $500^{\circ}C$ to $700^{\circ}C$ in air. The ATO nano powders are characterized by means of Thermogravimetry differential thermal analyzer (TG-DTA), X-ray diffraction (XRD), Brunauer, Emmett, and Teller adsorption (BET), Scanning electron microscopy (SEM) ATO nano powders with an average size of nm and the highest surface area 129 $m^2g^{-1}$ are obtained.

• Nuclear Engineering and Technology
• /
• v.42 no.1
• /
• pp.73-78
• /
• 2010

The suppression of molten salt vaporization is one of the key technical issues in the electrolytic reduction process developed for recycling spent nuclear fuel from light-water reactors Since the Hertz-Langmuir relation previously applied to molten salt vaporization is valid only for vaporization into a vacuum, a diffusion model was derived to quantitatively assess the vaporization of LiCl, $Li_2O$ and Li from an electrolytic reducer operating under atmospheric pressure. Vaporization rates as a function of operation variables were calculated and shown to be in reasonable agreement with the experimental data obtained from thermogravimetry.

• Macromolecular Research
• /
• v.16 no.3
• /
• pp.194-199
• /
• 2008

Four novel polyurethanes were prepared from 4-{(4-hydroxyphenyl)iminomethyl} phenol by reactions with two aromatic diisocyanates, 4,4'-diphenylmethane diisocyanate and toluene 2,4-diisocyanate, and two aliphatic diisocyanates, isophorone diisocyanate and hexamethylene diisocyanate. The polyurethanes formed were characterized by UV-vis, fluorescence, FT-IR, $^1H$-NMR, $^{13}C$-NMR, differential scanning calorimetry, thermogravimetry, and X-ray diffraction. The polymers were semi-crystalline and all polymers were soluble in polar aprotic solvents.

• Advances in materials Research
• /
• v.13 no.2
• /
• pp.103-114
• /
• 2024

Zeolites are microporous materials that find applications in different fields due to their numerous interesting properties. This research investigated the effect of leaching on unheated Ifon kaolin in dilute hydrochloric acid and sulphuric acid. The hydrothermal method synthesized zeolite-X type, and the resulting sample was characterized using different techniques. The silica/alumina ratio in the synthesized sample was approximately 5.6, while Infrared spectra confirmed that the synthesized material was Zeolite-X. Based on the X-ray diffraction patterns, other phases were also formed in addition to zeolite-X crystals. Thermogravimetry results indicated that the synthesized zeolite was relatively stable below 500℃, so its weight loss was only 13% after heating to about 200℃. A differential thermal analyzer confirmed this amount of weight loss, and endothermic and exothermic reactions were also observed for the samples calcined respectively at 700 and 900℃. Based on Brunauer-Emmett-Teller (BET) analyses, samples at 700℃ showed slower adsorption-desorption isotherms, pore volume, and sizes than those at 900℃. These results have shown that leaching and calcination temperature significantly affect the type of zeolite produced.