• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3306-3310
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• 2011

A series of novel linear aromatic ether ketone polymers containing triazole units were synthesized by click chemistry and their structures and properties were characterized by FT-IR, $^1H$ NMR, GPC, TGA, DSC and WAXD. The results showed that these polymers exhibited relatively small molecular weights distributions, good thermal stability and solvent-repelling which could have potential applications as engineering thermoplastic.

• Proceedings of the Korean Fiber Society Conference
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• 1994.10a
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• pp.135-136
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• 1994

Anionic water dispersible copolyesters were synthesized by the polycon-densation of dimethyl isophathalate/5-sodium sulfo dimethyl isophathalate with ethylene glycol/diethylene glycol. Structrual analyses such as NMR, Irm WAXD analyses were done and copolyesters were found to be correctly synthesized. Relation between feed ratio and composition ratio of EG/DEG in copolyesters was confirmed by NMR analysis. Solubility test was done to find out optimum conditon of DMS feed ration of 10 mol% in dimethyl esters. Water resistance of copolyesters decreased with the increase of DMS or DEG molar feed ratio.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.403-408
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• 1993

Hydroxypropyl chitin(HPCH) was prepared from chitin by reacting it with propylene oxide. The formation of liquid crystalline character of HPCH was investigated using halogenated organic solvents. Solid state $^{13}C$ NMR spectra for chitin and HPCH confirmed the incorporation of hydroxypropyl moiety. The degree of substitution of HPCH was around 0.8 as detected by elemental analysis. WAXD patterns of chitin and HPCH showed that an incorporation of hydroxypropyl unit in chitin contributed to reducing the crystallinity and enhancing the solubility in organic solvents. Polarized light microscopic pictures of concentrated HPCH solution showed that HPCH formed cholesteric liquid crystalline character at about 25w/v% solution in dichloroacetic acid and 1, 2-dichloroethane. Inherent viscosity of HPCH solution in a mixed solvent showed a transient decrease.

• Journal of the Korean Ceramic Society
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• v.41 no.1
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• pp.41-44
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• 2004

Hydrophilicity and hydrophobicity of pottery bodies can be controlled via chemical substitution of layered clay with hydrophilic and hydrophobic organics. In this study, organo-clay nanocomposites were prepared by ion-exchange of montmorillonite with dodecylamine and hexadecylamine, respectively. Substitution sites of organics and the interval changes of layered materials are characterized by FT-IR and WAXD and organics amounts loaded and water comtents contained by C/S analysis and TG-DSC. The organics were selectively intercalated so that increase layer interval from 12${\AA}\; to\;16{\AA}$. Organo-modified clay is changed to more hydrophobic comparing to clay itself.

• Polymer(Korea)
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• v.26 no.4
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• pp.483-491
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• 2002

Polyurethane (PU)/nylon 6 blends were prepared by melt blending with Haake Rheomix at $250^{\circ}C$. The compositions of PU/nylon 6 blends were 10/90, 20/80, 30/70, 40/60, and 50/50 (wt%). The effects of PU contents and blending time on the crystal structure, tan $\delta$, the tensile properties, and the impact behavior were investigated by means of WAXD and DMA, etc. The crystalline diffraction peaks are broadened, and their intensities are reduced with increasing PU contents and blending time. The glass transition temperature, the tensile strength, and the tensile modulus of the blends are also decreased and the elongation at break is increased. The influence of PU content on the crystal structure, tan 3, and the tensile properties of PU/nylon 6 blends is more significant than that of blending time. The impact strength of PU/nylon 6 (10/90 wt%) blends measured at 20 and $-35^{\circ}C$ could be greatly improved.

• Macromolecular Research
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• v.12 no.4
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• pp.367-373
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• 2004

We have developed a rigorous heat treatment method to improve the biocompatibility of chitosan as a tissue-engineered scaffold. The chitosan scaffold was prepared by the controlled freezing and lyophilizing method using dilute acetic acid and then it was heat-treated at 110$^{\circ}C$ in vacuo for 1-3 days. To explore changes in the physicochemical properties of the heat-treated scaffold, we analyzed the degree of deacetylation by colloid titration with poly(vinyl potassium sulfate) and the structural changes were analyzed by scanning electron microscopy, Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffractometry (WAXD), and lysozyme susceptibility. The degree of deacetylation of chitosan scaffolds decreased significantly from 85 to 30% as the heat treatment time increased. FT-IR spectroscopic and WAXD data indicated the formation of amide bonds between the amino groups of chitosan and acetic acids carbonyl group, and of interchain hydrogen bonding between the carbonyl groups in the C-6 residues of chitosan and the N-acetyl groups. Our rigorous heat treatment method causes the scaffold to become more susceptible to lysozyme treatment. We performed further examinations of the changes in the biocompatibility of the chitosan scaffold after rigorous heat treatment by measuring the initial cell binding capacity and cell growth rate. Human dermal fibroblasts (HDFs) adhere and spread more effectively to the heat-treated chitosan than to the untreated sample. When the cell growth of the HDFs on the film or the scaffold was analyzed by an MTT assay, we found that rigorous heat treatment stimulated cell growth by 1.5∼1.95-fold relative to that of the untreated chitosan. We conclude that the rigorous dry heat treatment process increases the biocompatibility of the chitosan scaffold by decreasing the degree of deacetylation and by increasing cell attachment and growth.

• Polymer(Korea)
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• v.27 no.6
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• pp.528-535
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• 2003

The effects of surfactants, organic solvents, and functional monomers on the emulsion polymerization of perfluoroalkyleoylacryaltes and n-alkylacrylates were investigated. In particular, the dependence of the surface properties, contact angle and water repellency on the crystal melting temperature (T$\_$m/) of the fluorocopolymer and the variation of polymer latex particle sizes was investigated. Using WAXD experiments and synthesizing different types of fluorocopolymers which have fallowing fluoroacrylaytes [CH$_2$=CHCO$_2$CH,$_2$(CF$_2$CF$_2$) nH] (n = 4, 5 or 6), the relationship between the molecular packing structure of pendent side groups of fluorocopolymers and the surface properties was also investigated. We observed that the structure of primary carbon atoms of pendent side groups of fluorocopolymers plays key role in determining the surface properties.s.

• Polymer(Korea)
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• v.37 no.1
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• pp.52-60
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• 2013

Partially hydrolyzed cellulose acetate (CA) fibers were prepared by treating CA fibers in aqueous $Na_2CO_3$ solutions of various concentrations. The deacetylation of CA fibers was confirmed through FTIR spectra and WAXD patterns. The hydrolysis was confined to the surface part of the CA fiber by controlling the treatment conditions. The resultant fibers had a sheath-core structure with a sheath component of regenerated cellulose and a core of non-hydrolyzed cellulose acetate. The SEM images of the surface-hydrolyzed CA fibers, the core of which was dissolved out using acetone as the solvent, showed that the sheath thickness increased with increasing alkaline concentration, indicating an increase in the hydrolyzed fiber, i.e., regenerated cellulose. Polarized FTIR analysis of the polyimide film rubbed with velvet fabrics of surface-hydrolyzed CA fibers showed that polyimide molecules were preferentially oriented to the rubbing direction.

• Polymer(Korea)
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• v.36 no.1
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• pp.9-15
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• 2012

We prepared a series of aromatic liquid crystals (LCs) based on wholly aromatic ester units with the reactive end group methyl maleimide by means of melt condensation method, and the resulting LCs were thermally crosslinked to produce liquid crystalline thermoset (LCT) films. The synthesized LCs and LCTs were characterized with Fourier transform infrared (FTIR) spectroscopy, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomechanical analysis (TMA), and polarizing optical microscopy (POM) with a hot stage. The glass transition temperature ($T_g$) and coefficient of thermal expansion are strongly affected by the mesogen units in their main chain structures. The $p$-substituted biphenyl LC was found to have the highest thermal property value.

• Composites Research
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• v.22 no.3
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• pp.18-28
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• 2009

Blends of poly(lactic acid) (PLA) and poly(butylene terephthalate) (PBT) were prepared by reaction extrusion with para-phenylene diisocyanate (PPDI). The crystallization behavior and biodegradability were investigated by using a differential scanning calorimeter (DSC), a wide angle X-ray diffractometer (WAXD), a contact angle goniometer, and a buffer solution containing esterase. The addition of PBT into PLA polymer matrix induced the cold crystallization of PLA phase, and the crystallization rate of PLA phase was significantly accelerated when both PBT and PPDI participated in the reaction with PLA simultaneously. But the chain extension caused by PPDI decreased the crystallinity and hydrophilicity of PLA and PBT phases. The crystallinity and hydrophilicity did not affect the biodegradability of PLA/PBT blends. However, phase separation between PLA and PBT in PLA/PBT blends increased the interfacial area exposed to the hydrolysis of enzyme, resulting in the improved degradability rate of PLA phase. In contrast, the improved interfacial adhesion between PLA and PBT matrices by the reaction with PPDI reduced the area exposed to the enzyme to decrease the degradation rate of PLA phase.