• Fibers and Polymers
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• v.5 no.2
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• pp.160-169
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• 2004

Polystyrene/layered silicate nanocomposites were prepared by melt intercalation. To examine the distribution of the clay in polymer matrix, small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) were used. Intercalated nanocomposites were obtained and their rheological properties were investigated. Microcellular nanocomposite foams were produced by using a supercritical fluid. As clay contents increased, the cell size decreased and the cell density increased. It was found that layered silicates could operate as heterogeneous nucleation sites. As the saturation pressure increased and the saturation temperature decreased, the cell size decreased and the cell density increased. Microcellular foams have different morphology depending upon the dispersion state of nanoclays.

• Food Science and Biotechnology
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• v.16 no.5
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• pp.691-709
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• 2007

Concerns on environmental waste problems caused by non-biodegradable petrochemical-based plastic packaging materials as well as consumer's demand for high quality food products has caused an increasing interest in developing biodegradable packaging materials using annually renewable natural biopolymers such as polysaccharides and proteins. However, inherent shortcomings of natural polymer-based packaging materials such as low mechanical properties and low water resistance are causing a major limitation for their industrial use. By the way, recent advent of nanocomposite technology rekindled interests on the use of natural biopolymers in the food packaging application. Polymer nanocomposites, especially natural biopolymer-layered silicate nanocomposites, exhibit markedly improved packaging properties due to their nanometer size dispersion. These improvements include increased mechanical strength, decreased gas permeability, and increased water resistance. Additionally, biologically active ingredients can be added to impart the desired functional properties to the resulting packaging materials. Consequently, natural biopolymer-based nanocomposite packaging materials with bio-functional properties have huge potential for application in the active food packaging industry. In this review, recent advances in the preparation and characterization of natural biopolymer-based nanocomposite films, and their potential use in food packaging applications are addressed.

• Proceedings of the Korean Society of Rheology Conference
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• 2003.05a
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• pp.17-20
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• 2003

No Abstract, See Full Text

• Macromolecular Research
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• v.15 no.1
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• pp.51-58
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• 2007

The approach studied in the present work produced an exfoliated state of clay layers via confinement of the charged nano-sized polystyrene (PS) beads within the gallery of swollen pristine clay. It was demonstrated that adsorption of the polymer nanobeads dramatically promotes expansion of the clay gallery. A comparative study of incorporation was conducted by employing organo-modified clay along with two different colloid polymer systems: electrostatically stabilized PS nanobeads and cationic monomer-grafted PS nanobeads. The mechanism of adsorption of the monomer-grafted polymer beads onto clay via cationic exchange between the alkyl ammonium group of the polymer nanobeads and the interlayer sodium cation of the layered silicate was verified by using several techniques. As distinct from the polymer nanobeads formed using conventional miniemulsion polymerization method, competitive adsorption of stabilizing surfactant molecules was be prevented by grafting the surface functional groups into the polymer chain, thereby supporting the observed effective adsorption of the polymer beads. The presence of surface functional groups that support the establishment of strong polymer-clay interactions was suggested to improve the compatibility of the clay with the polymer matrix and eventually play a crucial role in the performance of the final nanocomposites.

• Polymer(Korea)
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• v.28 no.2
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• pp.177-184
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• 2004

Polymer-clay nanocomposite containing the low amounts of clay shows improved physical, mechanical properties. In this study, allyl ester prepolymer was synthesised by reactions of the diallyl terephthalate monomers and the 1,3-butanediol monomers. Nanocomposites of allyl ester prepolymer and the two kinds of the organically layered silicate were prepared by using the intercalation method as well as the in-situ polymerization method using. By varying the amount of clay content, curing conditions, and feeding conditions. the nanocomposite was studied using X-ray diffraction. From XRD results, allyl ester-Cloisite 30 B nanocomposite made by the in-situ polymerization method shows better exfoliation behavior compared with the intercalation method. It can be said that the transesterification reaction between functional groups (-OH) of intercalant and monomers results in the increased gallery distance. Also mechanical and thermal properties indicate that the dispersity of clay is an important factor for improving physical properties of the nanocomposite.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.212-216
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• 2005

Benzotriazole which is used as a corrosion inhibitor for the zinc coated steel was intercalated into Na-MMT. X-ray diffraction experiments on intercalant/silicate composite samples demonstrated that the intercalation of intercalant leads to an increase in the spacing between silicate layers. Water soluble poly(ethylene-co-acrylic acid) (PEA) nanocomposites, to use as a coating agent, were prepared with these modified MMT. We found that mono-layered silicates were dispersed in PEA matrix and those resultants were exfoliated nanocomposites. From the result of salt spray test, we found that this coating agent prepared with water soluble poly(ethylene-co-acrylic acid) (PEA) nanocomposite provided good corrosion protection. These results were caused by decreasing the rate of oxygen permeation from silicate layers dispersed homogeneously in PEA matrix and the effect of corrosion inhibitor from benzotriazole.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.257-258
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• 2009

Nanocomposites of a epoxy resin are synthesized and evaluated the present study investigated. The effect of nanoclay additives on the properties of diglycidyl ether or bisphenol A(DGEBA) epoxy resin. DGEBA was mixed with 3~7 wt% organically modified layered silicate, Cloisite 30B for three hours. The average grain size of the specimens decreased with adding Cloisite 30B. The dielectric constant showed between 3.2 ~ 3.5 and the dielectric loss showed between 3.2 ~ 5.7 % in all specimens.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.4
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• pp.302-307
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• 2007

In this paper, a flap valve micropump with an ionic polymer-metal composite (IPMC) actuator was designed, fabricated, and experimentally characterized. A multilayered IPMC based on Nafion/layered silicate and Nafion/silica nanocomposites was fabricated for the actuation section of the micropump. The IPMC diaphragm, a key element of the mircopump, was designed so that the IPMC actuator was supported by a flexible polydimethylsiloxane (PDMS) structure at its perimeter. This design feature enabled a significantly high displacement of the IPMC diaphragm. The overall size of the micropump is $20{\times}20{\times}5$ ${mm}^3$. Water flow rates of up to 760 ${\mu}l$/min and a maximum backpressure of 1.5 kPa were recorded. A significant advantage of the proposed micropump is its low driven voltage from only 1-3 V. In addition, a simple and effective design, and an ease of manufacturing are other advantages of the present micropump.

• Applied Chemistry for Engineering
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• v.18 no.1
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• pp.48-53
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• 2007

Pulverization characteristics of H-kenyaite in vibration mill and exfoliation property in epoxy of pulverized H-kenyaite was investigated by using XRD, SEM, TEM. and particle size analyzer. Pulverization was conducted for 0.5~5 h. The particle morphology of sample pulverized for 1 h preserved plate-shape. However, this plate-shape disappeared in the sample pulverized for 3 h. The XRD pattern of sample pulverized for 1 h showed the characteristic peak of H-kenyaite. However, the peak disappeared in samples pulverized above 3 h, indicating severe destruction of H-kenyaite structure. TEM analysis for the kenyaite/epoxy nanocomposites exhibited only gallery expansion of 3~5 nm in non-pulverized sample, but dramatical large expansion of 5~10 nm in the samples pulverized during 1 h. This results confirm that the pulverization of wide plates composed of H-kenyaite particle have largely affect on the formation of an exfoliated kenyaite-polymer nanocomposite.