• Polymer Science and Technology
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• v.20 no.2
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• pp.135-140
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• 2009

• Polymer Science and Technology
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• v.18 no.1
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• pp.8-19
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• 2007

• Polymer Science and Technology
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• v.16 no.1
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• pp.48-56
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• 2005

• Polymer Science and Technology
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• v.19 no.6
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• pp.512-529
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• 2008

• Macromolecular Research
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• v.8 no.1
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• pp.44-52
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• 2000

Styrenic macromonomers with/without a silyloxy-functional group were synthesizedvia chain-end functionalization using 4-vinylbenzyl chloride as a terminating agent insec-butyllithium-initiated polymerization of styrene. The yields were 92 mol% for the silyloxy group and 88 mol% for the styrenic unit. Crystalline polystyrene-g-amorphous polystyrenes were synthesized by (η$^{5}$ -indenyl)-trichlorotitanium ((Ind)TiCl$_3$)-catalyzed copolymerizations of the macromonomers with styrene in the presence of methyl-aluminoxane (MAO) in toluene at 4$0^{\circ}C$. The macromonomer having $\alpha$, $\alpha$'-bis (4-[tert-butyldimethylsilyl-oxy]phenyl) group was also utilized for the preparation of a precursor of hydroxyl-functionalized syndio-tactic polystyrene. The obtained polymers were characterized by a combination of$^1$H, $^{13}$ C NMR spectroscopic, size exclusion chromatographic, and differential scanning calorimetric analysis. The (Ind)TiCl$_3$-catalyzed copolymerization of styrene with the macromonomer carrying the silyloxy functional group was found to be an efficient method to modify syndiotactic polystyrene without a great loss of physica] property by controlling the feud ratio of the macromonomer.

• Carbon letters
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• v.11 no.2
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• pp.107-111
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• 2010

We prepared the amine epoxy adducts (AEA)/thin multiwalled carbon nanotubes (TWCNTs) composite particles using nonsolvent based methods including dry mechano-chemical bonding(MCB) process and supercritical fluid (SCF) process. The resulting TWCNTs/AEA composite particles have been used as curing agents for urethane modified bispheol A type epoxy resin. The thermal, thermomechanical properties of the epoxy resins cured with TWCNTs/AEA composite particles were measured by DMA and the dispersion of CNT was characterized by SEM. Because of high degree of CNT dispersion, thermal and mechanical properties of the epoxy resin cured with TWCNTs/AEA composite particles prepared by SCF process are better than those cured with mechano-chemically prepared TWCNTs/AEA composite particles.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.11-15
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• 2003

In order to suppress a repulsive interfacial energy between hydrophilic clay and hydrophobic polymer matrix in preparing a polymer/clay nanocomposite, a third component of amphiphilic nature such as poly($\varepsilon$-caprolactone) (PCL) was introduced into the model system of styrene-acrylonitrile copolymers (SAN)/Na-montmorillonite. Once $\varepsilon$-caprolactone was polymerized in the presence of Na-rnontmorillonite, the successful ring-opening polymerization of $\varepsilon$-caprolactone and the well-developed exfoliated structure of PCL/Na-montmorillonite mixture were confirmed, Thereafter, SAN was melt-mixed with PCL/Na-montmorillonite nanocomposite, which resulted in that SAN matrix and PCL fraction were completely miscible to form homogeneous mixture with retention of the exfoliated state of Na-montmorillonite, exhibiting that PCL effectively stabilizes the repulsive polymer/clay interface and contributes the improvement of mechanical properties of the nanocomposites.

• Macromolecular Research
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• v.13 no.3
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• pp.206-211
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• 2005

Multi-walled carbon nanotubes (MWNTs) pre-treated by concentrated mixed acid or oxidized at high temperature were melt mixed with poly(methyl methacrylate) (PMMA) using a twin screw extruder. The morphologies and electrical properties of the MWNT/PMMA composites were investigated. The thermally treated MWNTs (t-MWNTs) were well dispersed, whereas the acid treated MWNTs (a-MWNTs) were highly entangled, forming large-sized clusters. The resulting electrical properties of the composites were analyzed in terms of the carbon nanotube (CNT) dispersion. The experimental percolation threshold was estimated to be $3 wt\%$ of t-MWNTs, but no percolation occurred at similar concentrations in the a-MWNT composites, due to the poor dispersion in the matrix.

• Macromolecular Research
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• v.13 no.5
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• pp.367-372
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• 2005

As a preliminary work for the preparation of nylon 6/c1ay nanocomposites by reactive extrusion, nylon 6/c1ay nanocomposites were prepared by anionic polymerization in a flask. In order to investigate the effect of the intercalation of clay layers, the clay feeding times, such as in pre-mixing where the clay was fed before initiation of polymerization and in after-mixing method where the clay was fed after initiation of polymerization, were changed. The appearance of the WAXD peak of nanocomposites prepared by the pre-mixing method was obvious and the tensile strength was decreased compared with that of pure nylon 6, which indicates that the clay layers were not dispersed and distributed. During the preparation of the nanocomposites by the after-mixing method, disordering of the clay layers was observed with increasing clay addition time and was suspected to result from the rapid polymerization of nylon 6 within the clay layers.

• Polymer Science and Technology
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• v.24 no.5
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• pp.474-480
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• 2013