• Polymer(Korea)
• /
• v.30 no.4
• /
• pp.318-325
• /
• 2006

Polypropylene-clay nanocomposites were studied by the modification of clay with amino silanes to introduce covalent bonds in nanocomposites, and prepared by melt-compounding with polypropylene, clay modified with amino silanes and maleic anhydride grafted polypropylene. The . .structure and surface properties of modified clay were determined by x-ray diffraction, infrared spectrum, and solid-state $^{29}Si$ nuclear magnetic resonance spectrum. The modification of clay with aminosilanes led to the increase of the silicate interlayers to about $19.8{\AA}$, the weakening effects of hydroxy group at $3650cm^{-1}$ and the signal of amine groups at -69 ppm proved that the modification had taken place.

• Polymer(Korea)
• /
• v.24 no.4
• /
• pp.571-577
• /
• 2000

A new type of filler for epoxy-clay nanocomposites has been prepared by the reaction of octadecyltrimethylammonium bromide and layered sodium montmorillonite (MMT) via an ion-exchange reaction. The gallery space was further modified by grafting the aminopropyl groups via a reaction between a octadecyltrimethylammonium-MMT and 3-aminopropyltriethoxysilane (APS). The interlayer modification of MMT was confirmed by XRD, IR, and solid-state $^{29}$ Si CP/MAS NMR. Furthermore, clay-polymer nanocomposites have been synthesized by the polymerization of diglycidyl ether of bisphenol A(DGEBA) and $C_{18}$ H$_{37}$ N($CH_3$)$_3$-APS-MMT. The resulting hybrid nanocomposites were characterized by XRD, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results proved that the organomontmorillonite could be exfoliated and uniformly dispersed in the epoxy matrix.

• Composites Research
• /
• v.18 no.1
• /
• pp.23-29
• /
• 2005

In this work, the effect of ozone treatment of montmorillonite (MMT) on the surface characteristics of montmorillonite and the thermal stability of MMT/polypropylene (PP) nanocomposites was investigated. The surface properties of MMT were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS). Also, the thermal stability of nanocomposites was investigated in thermogravimetric analysis (TGA). As a result, it was found that the silicate interlayers of the organically modified MMT (D-MMT) were increased by about 11${\AA}$, as compared with the MMT. Also, FT-IR showed that a new peaks at $2800\~2900\;cm^{-1}$ appeared due to the $CH_2$ mode in the D-MMT The ozone treatment of the MMT led to an increase of SiO or $SiO_2$ groups on MMT surfaces, resulting in increasing the oxygen-containing functional groups on MMT. The ozonized MMT had higher thermal stability than that of untreated nanocomposites. This was due to the improvement of interfacial bonding strengths, resulting from the acid-base interfacial interactions between PP and MMT.

• Journal of Conservation Science
• /
• v.21
• /
• pp.33-40
• /
• 2007

The consolidation application of SILRES BS OH 100 was investigated, which has been used for consolidation of the weathered shale. The liquid SILRES BS OH 100 was polymerized by the sol-gel reaction with air moisture, and the XRD patterns showed that the gel was an amorphous solid. The drastic weight reduction of the sample was found by differential thermal analysis, which was followed to the formation of $Si(OH)_4$ particles. After consolidation, the polymerized gel was filled into the voids within the shale. The capillary water absorption of the consolidated shale was reduced to 48.7%, and the abrasive strength was improved.

• Journal of Conservation Science
• /
• v.34 no.3
• /
• pp.167-177
• /
• 2018

The Bayon style Avalokitesvara statue from the $13^{th}$ century Angkor period is on display at the Cambodia Angkor Conservation Office. This statue is composed of dark green felthspathic greywacke, the surface of which has been shown light brown discoloration, detected calcite crystallization. As a result of condition assessment, the statue was damaged due to overlap scaling and cracking. Ultrasonic tests have investigated remarkable physical weathering area, flaking and fragmentation in lower velocity. The physical condition of the statue requires a conservation method that improves the binding power. To protect against salt weathering and to ensure physical stability, new conservation material composed of mixed ethyl silicate and sandstone powder similar to that composing the statue was created. The material affected by damage was removed and replaced with the new conservation material.

• Journal of the Korean Applied Science and Technology
• /
• v.21 no.3
• /
• pp.231-237
• /
• 2004

Ga-MFI was synthesized by a hydrothermal process at atmospheric pressure. The effect of mole ratios of reactants on crystallization was also investigated thoroughly. The characteristics of synthesized Ga-MFI was compared with ZSM-5. The synthesis of Ga-MFI was carried out with five different mole-compositions of $\underline{a}SiO_2-\underline{b}Ga_2O_3-\underline{c}Na_2O-\underline{d}TPA_2o-\underline{e}H_2O$. The synthesized Ga-MFI and ZSM-5 were characterized by XRD and FT-IR. The inorganic cation ($Na^+$) and water played an important role in crystallinity and the organic cation ($TPA^+$) as a template played a great influence on yields. With the increase in the amount of $Ga^{3+}$, crystallization time was increased. With a fixed $SiO_2/Ga_2O_3$ ratio of 400, the optimum reaction condition was obtained at $H_2O/SiO_2$=30${\sim}$35, $Na_2O/SiO_2$=0.5${\sim}$0.6, and $TPA_2O/Na_2O$=1${\sim}$1.25. In these cases, the crystallinity and yield were more than 95% and 90%, respectively. By comparing IR spectrum of Ga-MFI with those of ZSM-5 and silicalite, it was found that Ga-MFI showed a unique peak at 970 $cm^{-1}$, which may be used to identify Ga-MFI from ZSM-5 and silicalite.

• Polymer(Korea)
• /
• v.25 no.3
• /
• pp.421-426
• /
• 2001

11-Aminododecanoic acid, to insert the functional group of -COOH reacted with the end group of poly($\varepsilon$-caprolactone) diol, and cetyltrimethylammonium bromide (CTMA), to increase the d-spacing of Montmorillonite (MMT), were intercalated into $Na^+;_-$MMT. The modified MMT was reacted with poly(${varepsilon}-caprolactone$) diol ($M_n{=2000$) in THF solution at $80^{\circ}C$ for 4 hrs. After reaction, poly(${varepsilon}-caprolactone$) ($M_n{=80000$) was mixed into the solution for 12 hrs. To prepare the PCL/clay nanocomposite film this solution was cast into the silicon mold at $60^{\circ}C$ in vacuum oven for 6 hrs. From the results of XRD and TEM, it was found that the exfoliated PCL/clay nanocomposite were prepared. The effects of the amount of MMT on the mechanical properties and thermal properties of PCL/clay nanocomposites have been investigated by tensile tester and DSC. Because the MMT was dispersed homogeneously in PCL matrix, the Young's modulus of the nanocomposite were found to be excellent. However, MMT dispersed in PCL matrix had almost no effect on the tensile strength of the composites. The crystallization temperature of PCL increased in proportion to 3 wt% MMT in the PCL matrix.

• Polymer(Korea)
• /
• v.27 no.2
• /
• pp.135-141
• /
• 2003

A series of organophilic montmorillonites (MMTs) modified with various alkyl siloxane amino oligomer groups have been synthesized and their properties were investigated. New organophilic MMTs containing siloxane amino oligomers with alkyl group instead of conventional alkyl amines were synthesized to improve thermal stability as well as gallery spacing. The organophilic MMTs were synthesized from MMT by utilizing the siloxane amino oligomers with various alkyl groups in the water/dioxane solution, which was performed without aq. HCl. Thermal decomposition temperature, gallery spacing, and hydrophobicity of synthesized organophilic MMTs were investigated. X-ray diffraction and TEM experiment results on new organophilic MMTs demonstrated that introduction of siloxane amine oligomers increased d-spacing between silicate layers. The decomposition temperatures of new organophilic MMTs measured by TGA was remarkably improved above 200℃ as compared with those of conventional alkyl substituted organophilic MMTs.

• Polymer(Korea)
• /
• v.31 no.6
• /
• pp.485-490
• /
• 2007

Hard coating was made on a polycarbonate plate using a sol-gel process with a melamine derivative and silicates, and examined as potential substitutes for automobile glass. Methylated poly(melamine-co-formaldehyde), tetraethoxysilane, and phenyltriethoxysilane were used to form a coating solution. The coatings on the polycarbonate plate were deposited using a sol-gel process. Poly(methyl methacrylate) was coated on the surface of polycarbonate in order to improve adhesion property. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Adding the melamine derivative to the coating solution, the pencil hardness of the coating was improved. The hardness of a 3H class pencil, excellent abrasion resistance, and surface uniformity were found in the coated polycarbonate surface.

• Journal of the Korea Concrete Institute
• /
• v.21 no.4
• /
• pp.441-447
• /
• 2009

This paper presents a detailed experimental study on the sulfate resistance of specimens made with portland cement exposed to sulfate attack. The mortar specimens were immersed in a 5% sodium sulfate solution for 360 days and regularly monitored for visual damage, compressive strength loss and expansion. In addition, at the end of 360 days, the products of sulfate attack and the mechanism of attack were investigated through X-ray diffraction, TG&DSC and scanning electron microscopy. The test results indicated that the sulfate deterioration data was ordinary portland cement > sulfate resistance portland cement > low heat portland cement. The microstructural studies indicated that the main reaction product of deterioration of the mortar specimens was the formation of ettringite, gypsum and thaumasite due to sulfate attack. For portland cement matrices, a low heat cement matrix containing the lowest C3A and silicate ratio (C/S) was beneficient against the sulfate attack.