• Polymer(Korea)
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• v.29 no.2
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• pp.190-197
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• 2005

Nanocomposites of three different polyesters with dodecyltriphenylphosphonium-montmorillonite $(C_{12}PPh-MMT)$ as an organoclay are compared with their thermal properties, mechanical properties, and morphologies. Poly (butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET), and poly(trimethylene terephthalate) (PTT) were used as matrix polymers in the fabrication of polyester nanocomposite fibers. The variations of their properties with organoclay content in the polymer matrix and draw ratio (DR) are discussed. Transmission electron microscopy (TEM) micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nano-scale, although some clay particles are agglomerated. We also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the polyester nanocomposite fibers. Even polymers with low organoclay contents $(<5\;wt\%)$ were found to exhibit much higher strength and modulus values than pure polyester fibers. In the cases of all polyester hybrid fibers, the values of the tensile mechanical properties were found to decrease linearly with increasing DR. However, the initial tensile modulus of the PTT hybrid fibers were found to be independent of DR.

• Clean Technology
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• v.19 no.4
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• pp.401-409
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• 2013

BBiodegradable polymers have attracted great attention because of the increased environmental pollution by waste plastics. In this study, PLA (polylactic acid)/Clay-20 (Cloisite 20) and PLA (polylactic acid)/PBS (poly(butylene succinate)/Clay-20 (Cloisite 20) nanocomposites were manufactured in a twin-screw extruder. Specimens for mechanical properties of PLA/Clay-20 and PLA/PBS (90/10)/Clay-20 nanocomposites were prepared by injection molding. Thermal, mechanical, morphological and raman spectral properties of two nanocomposites were investigated by differential scanning calorimetry (DSC), tensile tester, scanning electron microscopy (SEM) and raman-microscope spectrophotometer, respectively. In addition, hydrolytic degradation properties of two nanocomposites were investigated by hydrolytic degradation test. It was confirmed that the crystallinity of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposite was increased with increasing Clay-20 content and the Clay-20 is miscible with PLA and PLA/PBS resin from DSC and SEM results. Tensile strength of two nanocomposites was decreased, but thier elongation, impact strength, tensile modulus and flexural modulus were increased with an increase of Clay-20 content. The impact strength of PLA/Clay-20 and PLA/PBS/Clay-20 nanocomposites with 5 wt% of Clay-20 content was increased above twice than that of pure PLA and PLA/PBS (90/10). The hydrolytic degradation rate of PLA/Clay-20 nanocomposite with 3 wt% of Clay-20 content was accelerated about twice than that of pure PLA. The reason is that degradation may occur in the PLA and Clay-20 interface easily because of hydrophilic property of organic Clay-20. It was confirmed that a proper amount of Clay-20 can improve the mechanical properties of PLA and can control biodegradable property of PLA.

• Elastomers and Composites
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• v.54 no.3
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• pp.201-208
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• 2019

Superabsorbent hydrogel (SAH) is a lightly crosslinked hydrophilic functional polymer material comprising a flexible chain structure, which can absorb and retain high amounts of water or aqueous fluids even under high pressure. Therefore, it is important to improve their characteristics such as absorption performance, residual monomer content, and water permeability. SAH nanocomposites were prepared using clay mineral as an inorganic filler and the influence of post-treatment processes such as quenching and aging process on their properties was studied. In addition, surface-crosslinking process was applied to improve the absorption performance associated with mechanical properties and water permeability. The structure of the SAH was characterized using attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy.

• Polymer(Korea)
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• v.36 no.4
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• pp.478-485
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• 2012

A series of transparent polyimide (PI) nanocomposite films was synthesized from bicyclo(2,2,2)oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTDA) and 1,3-bis(3-aminophenoxy)benzene (BAPB) with various organoclay contents via solution intercalation polymerization to poly(amic acid)s, followed by thermal imidization. Varying organoclay loading in a range of 0 to 1.5 wt% produced variations in the optical transparency, morphology, and oxygen barrier property of the hybrids. An optimum oxygen barrier property was observed for the hybrids containing 1.0 wt% Cloisite 30B; these properties were degraded gradually by further increases in the clay content. The PI hybrid films were found to exhibit excellent optical transparency and almost no color. However, the transparency of the hybrid films decreased slightly with increasing organoclay content. Transparent PI hybrid films containing 1.0 wt% Cloisite 30B were stretched equi-biaxially with various stretching ratios in a range of 100-140% to investigate their optical transparency and oxygen permeability in detail; the variations of clay dispersion and morphology were also determined as a function of equi-biaxial stretching ratio. PI hybrid films with ${\geq}120%$ stretching were found to contain homogeneously dispersed clay in the polymer matrix and exfoliated nanocomposites. The highest barrier to oxygen permeation was found at an equi-biaxial stretching ratio of 130%.

• Polymer(Korea)
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• v.31 no.6
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• pp.518-525
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• 2007

The thermomechanical properties and morphologies of nanocomposite fibers of poly(ethylene terephthalate)(PET) incorporating thermally stable organoclays are compared. Dodecyltriphenyl-phosphonium-mica($C_{12}PPh-Mica$) and 1-hexadecane benzimidazole-mica ($C_{16}BIMD-Mica$) were used as reinforcing fillers in the fabrication of PET hybrid fibers. Dispersions of organoclays with PET were studied by using the in-situ polymerization method at various organoclay contents to produce nano-scale composites. The thermo-mechanical properties and morphologies of the PET hybrid fibers were determined using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X-ray diffraction (XRD), electron microscopy (SEM and TEM), and a universal tensile machine (UTM). Transmission electron microscopy (TEM) micrographs show that some of the clay layers are dispersed homogeneously within the polymer matrix on the nano-scale, although some clay particles are agglomerated. We also found that the addition of only a small amount of organoclay is enough to improve the thermal stabilities and mechanical properties of the PET nanocomposite fibers. Even polymers with low organoclay content (<5 wt%) were found to exhibit much higher thermo-mechanical values than pure PET fibers.

• Polymer(Korea)
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• v.26 no.3
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• pp.381-388
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• 2002

The properties of polyurethane (PU) nanocomposites with organoclay have been compared in terms of their thermo-mechanical properties, morphology, and gas permeability. Hexadecylamine-montmorillonite ($C_{16}$-MMT) was used as an organoclay to make PU hybrid films. The properties were investigated as a function of organoclay content (1-4 wt%) in the PU matrix. Transmission electron microscopy (TEM) photographs showed that most clay layers were dispersed homogeneously into the matrix polymer in nano-scale, although some particles of clay were agglomerated. We also found that the addition of only a small amount of organoclay was enough to improve the thermal stabilities and mechanical properties of PU hybrid films while gas permeability was reduced. Even at low organoclay content (<5 wt%), the PU nanocomposite showed much better thermo-mechanical properties, and lower gas permeability than pure PU.

• Polymer(Korea)
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• v.25 no.6
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• pp.876-883
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• 2001

A thermotropic liquid crystalline polyester (TLCP) containing a side group was, synthesized from ethoxyhydroquinone and bromoterephthalic acid. Intercalation of TLCP in layered clays is accomplished by heating the polymer with hexadecyl ammonium-montmorillonite ($C_{16}$) above melting transition temperature ($T_m$). Liquid crystallinity of the TLCP/$C_{16}$-hybrid was observed up to 6 wt% $C_{16}$-MMT. Some of the $C_{16}$-MMTs in TLCP were highly dispersed in a nanometer scale, but some of them were agglomerated. Thermal and morphological properties of the nanocomposites were examined by differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), polarized optical microscope, and electron microscopes (SEM and TEM).

• Polymer(Korea)
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• v.25 no.2
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• pp.263-269
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• 2001

MAPTAC-MMT was prepared by exchanging the mineral cation (sodium montmorillonite) with 3-(methacryloyl amino) propyltrimethyl ammonium chloride, thus rendering the mineral organophilic and forming polymerizable moieties directly bonded to the surface of montmorillonite (MMT). Thermoresponsive nanocomposites (PNIPAM-MMT) were synthesized by polymerization of N-isopropyl acrylamide in an aqueous suspension of MAPTAC-MMT at room temperature. Thermoresponsive nanocomposites exhibited a low critical solution temperature (LCST) similar to unmodified poly(N-isopropyl acrylamide) (PNIPAM). The LCST of thermoresponsive nanocomposites decreased in proportion to the amount of MAPTAC-MMT. TGA results showed that the thermal stability of thermoresponsive nanocomposites was improved compared to PNIPAM itself the thermoresponsive polymer.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.139-140
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• 2006

Some of novel halogen-free, elastomeric flame retardants for nylon-6 have been developed. It is found that the S-ENP and clay have a synergistic flame retardant effect on nylon-6 resulted from the formation of two barriers on the nanocomposite residue surface at the end of combustion. A novel flame retardant ternary nanocomposite of nylon-6/ENP/nano-Magnesium hydroxide was also fabricated. The new ternary composite has better flame retardancy and thermal stability than the conventional one because nano-MH can disperse much more homogeneous in the new ternary composite than in the conventional one.

• Macromolecular Research
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• v.14 no.2
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• pp.179-186
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• 2006

In the present work, low density polyethylene (LDPE)/aliphatic polyester (APES)/organoclay ternary nanocomposites were prepared. In particular, the effect of a compatibilizer, polyethylene-graft-maleic anhydride (PE-g-MAH), on the morphology and properties of the ternary nanocomposites was investigated. LDPE/APES/organoclay nanocomposites were prepared through melt intercalation method using two different kinds of organoclay. The dispersibility of silicate clays in the nanocomposites was investigated by X-ray diffraction and atomic force microscopy. The ternary nanocomposites showed higher tensile properties than the LDPE/APES blend did. The dispersibility and properties of nanocomposites containing Cloisite 30B were better than those of the nanocomposites containing Cloisite 20A. Unlike Cloisite 20A, hydroxyl groups in the intercalants in Cloisite 30B interlayer underwent a certain polar interaction with the carboxyl group of APES, favoring the intercalation of APES chains and the formation of LDPE/APES/Closite 30B nanocomposites. However, the introduction of the polar hydroxyl groups also enhanced the interaction with the silicate surface at the same time, thereby rendering somewhat difficult the replacement of the surface contacts by LDPE chains, and impeding the extensive intercalation and further exfoliation of Cloisite 30B in the LDPE/APES matrix. The compatibilizer enhanced the intercalation of the polymer chain inside the clay gallery and thus improved the mechanical properties of the ternary nanocomposites. Rheological measurements of the nanocomposites via frequency sweep experiment indicated a certain interaction between the clay platelet and the polymer molecules in the melted state.