• Macromolecular Research
• /
• v.15 no.5
• /
• pp.443-448
• /
• 2007

To improve the sound damping effect of flexible polyurethane foam, with an open-cell structure, various plate-like fillers, such as bentonite, organophilic clay and sodium montmorillonite intercalated with poly(ethylene glycol), were incorporated for the creation of nanocomposites. The plate-like fillers effectively improved the sound damping within the high frequency range. The structures of the nanocomposites and foam were examined using X-ray diffraction and scanning electron microscopy. The mechanical properties and flammability of the foams were also examined.

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

• Steel and Composite Structures
• /
• v.38 no.2
• /
• pp.177-187
• /
• 2021

The effect of nanoparticle volume fraction on the elastic properties of a polymer-based nanocomposite was experimentally investigated and the obtained results were compared with various existing theoretical models. The nanocomposite was consisted of high density polyethylene (HDPE) as polymeric matrix and 0, 0.5, 1 and 1.5 wt.% multi walled carbon nanotubes (MWCNTs) prepared using twin screw extruder and injection molding technique. Nanocomposite samples were molded in injection apparatus according to ASTM-D638 standard. Therefore, in addition to morphological investigations of the samples, tensile tests at ambient temperature were performed on each sample and stress-strain plots, elastic moduli, Poisson's ratios, and strain energies of volume units were extracted from primary strain test results. Tensile test results demonstrated that 1 wt.% nanoparticles presented the best reinforcement behavior in HDPE-MWCNT nanocomposites. Due to the agglomeration of nanoparticles at above 1 wt.%, Young's modulus, yielding stress, fracture stress, and fracture energy were decreased and Poisson's ratio and failure strain were increased.

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

• Applied Chemistry for Engineering
• /
• v.25 no.1
• /
• pp.14-19
• /
• 2014

Nanocomposites based on poly(methyl methacrylate) (PMMA)/poly(vinylidene fluoride) (PVDF) and poly(ethylene terephthalate) (PET)/(PVDF) blended with carbon fibers (CF) and carbon nanotube (CNT) were prepared by melt mixing in the twin screw extruder. Morphologies of the PMMA/PVDF/CF/CNT and PET/PVDF/CF/CNT nanocomposites were investigated using SEM. The aggregation of CNT was observed in PMMA/PVDF/CF/CNT nanocomposites while the good dispersion of CNT was shown in PET/PVDF/CF/CNT nanocomposites. In SEM image of PET/PVDF/CF/CNT nanocomposite, the CNT were mainly located at the PET domain of phase-separated PET/PVDF blend due to the ${\pi}-{\pi}$ interaction between the phenyl ring of PET and graphite sheet of the CNT's surface. In addition, a fairly good compatibility between PET/PVDF matrix and CF was shown in the SEM image. In the case of PET/PVDF nanocomposites blended with the co-addition of CF and CNT, the volume electrical resistivity decreased while no change was observed in PMMA/PVDF/CF/CNT composites. The degree of CNT dispersion in morphology results was consistent with the electrical conductivity results. From the DSC results, the crystallization temperature (Tc) of PET/PVDF/CF/CNT nanocomposites increased due to the co-addition of CF and CNTs acting as a nucleating agent. Flexural modulus of PET/PVDF/CF/CNT were sharply enhanced due to increasing the interaction between PET and CF.

• Interaction and multiscale mechanics
• /
• v.4 no.3
• /
• pp.173-185
• /
• 2011

A multiscale modeling scheme that addresses the influence of the nanoparticle size in nanocomposites consisting of nano-sized spherical particles embedded in a polymer matrix is presented. A micromechanics-based constitutive model for nanoparticle-reinforced polymer composites is derived by incorporating the Eshelby tensor considering the interface effects (Duan et al. 2005a) into the ensemble-volume average method (Ju and Chen 1994). A numerical investigation is carried out to validate the proposed micromechanics-based constitutive model, and a parametric study on the interface moduli is conducted to investigate the effect of interface moduli on the overall behavior of the composites. In addition, molecular dynamics (MD) simulations are performed to determine the mechanical properties of the nanoparticles and polymer. Finally, the overall elastic moduli of the nanoparticle-reinforced polymer composites are estimated using the proposed multiscale approach combining the ensemble-volume average method and the MD simulation. The predictive capability of the proposed multiscale approach has been demonstrated through the multiscale numerical simulations.

• Polymer(Korea)
• /
• v.27 no.6
• /
• pp.569-575
• /
• 2003

The flame retardancy was investigated when the halogenated flame retardant, decabromodiphenyl oxide (DBDPO) and chlorinated paraffin wax (CPW), was added to the polypropylene (PP) / montmorillonite (MMT) nanocomposites. The flame retardancy of polymer resin could be improved not only by addition of flame retardant but also with nanoparticles compositions. The effect of the contents of flame retardant and nanoparticles on the flame retardancy of polypropylene/ montmorillonite nanocomposite systems was thoroughly examined in terms of limited oxygen index (LOI) and cone calorimetry. As a results of cone calorimetry, the heat release rate (HRR) was reduced by the flame retardant DBDPO and CPW, and CPW was a little better than DBDPO. The LOI increased from flammable region (LOI<19) to nonflammable region (LOI>20) for all the flame retardants used in this study. Especially, the improvement in flame retardancy by compounding with PP and MMT was better than that by adding flame retardant to polypropylene. So, the addition of flame retardant after compounding with montmorillonite was more efficient than simple addition of flame retardant.

• Journal of Adhesion and Interface
• /
• v.11 no.3
• /
• pp.106-111
• /
• 2010

Na-MMT intercalated with PEGMA macromer was prepared using an EtAc/acetone mixture (1/1 by volume) as a solvent. PEGMA/(Na-MMT)-co-MMA/MA nanocomposites was synthesized by copolymerizing intercalated compound with MMA and MA, and then characterization was performed. The results of X-ray diffraction (XRD) showed that in the case of Na-MMT intercalated with PEGMA macromer the d-spacings of silicate of Na-MMT increased with increasing of Na-MMT loading. As the Na-MMT loading increases Tg showed increasing trend through the DSC measurement. TGA result showed that thermal stability of PEGMA/(Na-MMT)-co-MMA/MA nanocomposites improved a little more than the pure PEGMA-co-MMA/MA.

• Journal of the Korean Ceramic Society
• /
• v.47 no.3
• /
• pp.205-209
• /
• 2010

In the last (fourth) section, the discussion will entail a silicon-nitride/silicon-carbide nanocomposite, produced by pyrolysis of liquid polymer precursors, demonstrating one of the lowest creep rates reported so far in ceramics at the comparable temperature of $1400^{\circ}C$. This was first achieved by avoiding the oxynitride glass phase at the intergrain boundaries. One important factor in the processing of these nanocomposites was the use of the electrical field assisted sintering method.

• Carbon letters
• /
• v.12 no.2
• /
• pp.102-106
• /
• 2011

Carbon nanotubes (CNTs) have been synthesized by ferrocene-catalyzed pyrolysis of toluene. The influences of the experimental conditions on the morphology and microstructure of the product have been analyzed. To find the proper temperature for synthesis of CNTs, the experiment was performed in a temperature range from 800 to $1100^{\circ}C$. From content variation of ferrocene and thiophene as the catalyst, morphological change of carbon nanotubes has been observed. Also, the influence of the gas ratio of hydrogen and argon on the nanotube samples was analyzed by scanning electron microscopy and transmission electron microscopy.