• Advances in materials Research
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• v.2 no.2
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• pp.99-109
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• 2013

In the present investigation, nanocomposite films with poly(methyl methacrylate) (PMMA) as a polymer matrix and barium titanate as a filler were prepared by solution casting method. Barium titanate nano particles were prepared using Ti(IV) triethanolaminato isopropoxide and hydrated barium hydroxide as precursors and tetra methyl ammonium hydroxide (TMAH) as a base. The nanocomposite films were characterized using XRD, FTIR, SEM and dielectric spectroscopy techniques. Dielectric measurements were performed in the frequency range 100 Hz-10 MHz. Dielectric constant of nanocomposites were found to depend on the frequency, the temperature and the filler fraction. Dissipation factors were also influenced by the frequency and the temperature but not much influenced by the filler fractions. The 10 wt% of BT-PMMA nanocomposite had the lowest dielectric constant of 3.58 and dielectric loss tangent of 0.024 at 1MHz and $25^{\circ}C$. The dielectric mixing model of Modified Lichtenecker showed the close fit to the experimental data.

• Journal of Technologic Dentistry
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• v.36 no.3
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• pp.165-169
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• 2014

Purpose: This study is a mechanical strength supplementation of denture base resin Polymethyl methacrylate (PMMA) is in general use for denture base resin of the partial and full denture, however, The polymerization process of PMMA is not stabilized. Because of compatibility problems, preceding studies were performed, which were enhancing mechanical strength(Camilo Machado 2007),(Ana M. 2008), addition filler to materials property(Ayse Mese, 2008), self curing method(Hiroshi Shimizu, 2008). Methods: The carbon fiber and polyacetal filler, reinforced the mechanical strength for improving the stability of denture base resin were supplemented to the self cured resin. The Modulus of elasticity and the restoring force were calculated by tensile test. Results: The strengths of the heat and self cured resin were respectively decreased and increased, when the filler was supplemented to the denture base resin and the modulus of elasticity of both heat and self cured resin were not increased, when the filler was supplemented to the denture base resin. Conclusion: The restoring forces of self cured resin containing 10% filler were increased, when the filler was supplemented to the denture base resin.

• Carbon letters
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• v.11 no.2
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• pp.83-89
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• 2010

We prepared polycarbonate (PC)/poly(methyl methacrylate) (PMMA)/multiwall carbon nanotube (MWCNT) nanocomposites by co-rotating twin screw extruder at 533 K. Thermal analysis results indicate that the miscibility of PC and PMMA is enhanced by MWCNTs. Bead necklace-like morphology of PMMA-rich phase is observed in PC/PMMA/MWCNT nanocomposites with increasing PMMA weight fraction due to the bead necklace-like morphology. The tensile strength of PC/PMMA (75/25)/MWCNT (1 wt.%) nanocomposite is 3% higher than those of PC/PMMA (75/25) alloy. Suppression of die swell by MWCNT filler is observed in the melt flow of PC/PMMA/MWCNT nanocomposites during extrusion.

• Journal of Biomedical Engineering Research
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• v.40 no.4
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• pp.137-142
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• 2019

Numerous efforts are being made to develop an ideal dermal filler that should be bio-compatibility, non-immunogenicity, long-lasting and biodegradable without a toxic secretion. Biomaterials of dermal fillers are hyaluronic acid filler, calcium filler, PMMA filler and collagen filler depending on the ingredient. Although hyaluronic acid (HA) is most widely used, it has shortages such as short shelf life and low mechanical strength compare to extracellular matrix (ECM). The cartilage ECM composed of collagen type II, proteoglycans, glycosaminoglycans (GAGs) and in a minor part with glycoproteins. In this study, we developed a cartilage ECM injectable filler capable of improving biocompatibility and longevity compared with hyaluronic acid (HA) fillers. The ECM hydrogel was cross-linked by the reaction of N-(3-Dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) for mechanical enhancement. Prepared ECM filler was compared with cross-linked HA by butanediol diglycidyle ether (BDDE), which is the most widely used natural polymers for dermal filler. In the results, the articular cartilage ECM hydrogel has great potential as a dermal filler to improve the biophysical and biological performance.

• Composites Research
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• v.31 no.5
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• pp.282-287
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• 2018

In this paper, we explore interfacial properties of the mineralized CNTs when they are employed as reinforcing fillers in a polymer nanocomposite using molecular dynamics (MD) simulations. Recently, several studies on mineralizing carbon nanotubes (CNTs) with an aid of nitrogen doping to CNTs have been reported. However, there is a lack of studies on the reinforcing effects of the mineralized CNTs when it is employed as a filler of nanocomposites. Silica ($SiO_2$) is used as a mineral material and poly (methyl metacrylate) (PMMA) is used as a polymer matrix. Pull-out simulations are conducted to obtain the interfacial energy and the interfacial shear stress. It was found that the silica mineralized CNTs have higher interfacial interaction with the polymer matrix. In the future, by examining various thermomechanical properties of the mineralized-CNT-filler/polymer nanocomposites, we will search for potential applications of the novel reinforcing filler.

• Journal of the Korean institute of surface engineering
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• v.50 no.3
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• pp.198-205
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• 2017

Thermal dissipation was investigated for poly methyl methacrylate (PMMA) composite films containing graphite and multi wall carbon nanotube(CNT) powders as filler materials. After mixing PMMA with fillers, solvent, and dispersant, the pastes were prepared by passing through a three roll mill for three times. The prepared pastes were coated $15{\sim}40{\mu}m$ thick on a side of 0.4 mm thick aluminium alloy plate and dried for 30 min at $150^{\circ}C$ in an oven. The content of fillers in dried films was varied as 1, 2, and 5 weight % maintaining the ratio of graphite and CNT as 1:1. Raman spectra from three different samples exhibited D, G and 2D peaks, as commonly observed in graphite and multi wall CNT. Among those peaks, D peak was prominent, which manifested the presence of defects in carbon materials. Thermal emissivity values of three samples were measured as 0.916, 0.934, and 0.930 with increasing filler content, which were the highest ever reported for the similar composite films. The thermal conductivities of three films were measured as 0.461, 0.523, and $0.852W/m{\cdot}K$, respectively. After placing bare Al plate and film coated samples over an opening of a polystyrene box maintained for 1 h at $92^{\circ}C$, the temperatures inside and outside of the box were measured. Outside temperatures were lower by $5.4^{\circ}C$ in the case of film coated plates than the bare one, and inside temperatures of the former were lower by $3.6^{\circ}C$ than the latter. It can be interpreted that the PMMA composite film coated Al plates dissipate heat quicker than the bare Al plate.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.758-763
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• 2011

In this work, polymer composite electrolytes were prepared by a blend of poly(methyl methacrylate) (PMMA) and poly(ethylene oxide) (PEO) as a polymer matrix, propylene carbonate as a plasticizer, $LiClO_4$ as a salt, and by containing a different content of $TiO_2$, by using the solution casting method. The crystallinity and ionic conductivity of the polymer electrolytes was evaluated using X-ray diffraction(XRD) and AC impedance method, respectively. The morphology of composite electrolyte film was analyzed by SEM method. From the experimental results, by increasing the $TiO_2$ content, crystallinity of PEO was reduced, and ionic conductivity was increased. In particular, the ionic conductivity was dependent on the content of $TiO_2$ and showed the highest value 15 wt%. However, when $TiO_2$ content exceeds 15 wt%, the ionic conductivity was decreased. According to the surface morphology, the ionic conductivity was decreased because the polymer composite electrolytes showed a heterogenous morphology of fillers due to immiscibility or aggregation of the filler within the polymer matrix.

• Polymer(Korea)
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• v.34 no.1
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• pp.1-7
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• 2010

To enhance the transport properties of gas separation membrane, we prepared 6FDA-6FpDA based polyimide membrane with PMMA-graft-silica nanoparticles. The silica was grafted PMMA which is miscible with 6FDA-based polyimide after surface treatment by 3-methacryloxypropyltrimethoxysilane ($\gamma$-MPS). The untreated silica/6FDA-6FpDA membrane showed greater permeability and less selectivity than PMMA-g-silica/6FDA-6FpDA due to its low dispersion. The transport properties of PMMA-g-silica/6FDA-GFpDA membrane were measured as a function of filler concentration. These membranes were evaluated using pure gases (He, $O_2$, $N_2$, $CO_2$). The increase in permeation was attributed to changes in the free volume distribution until 1 wt%. After 1 wt%, the permeability was decreased by excess silica which decreased effective area in polymer matrix. The selectivity was decreased with increasing permeability on the whole. However, the selectivity of $CO_2$ showed more enhance value.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.1
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• pp.18-24
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• 1982

The Tree phenomenon of the PMMA resin depends on an annex of the inorganic fillers and water. If the internal of an arganic insulating materials exist the fault of inorganic fillers, Void and Projecting part, the high voltage concentrates in this place. It leaves a trace about the partical breakdown and this phenomenon develops into the degration of insulating material. This paper researchses that have an effect on the tree phenomenon by the inorganic fillers and water. The results is as follow. (1) The growth of tree are less the influence of inorganic fillers. Because , the constant of water are more. (2) If the tree branches contact the inorganic filler, the advance are relaxation.

• Journal of Adhesion and Interface
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• v.13 no.3
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• pp.137-144
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• 2012

Chemical functionalization of carbon nanomaterials (CNMs) is generally carried out for increasing interfacial adhesion between filler and polymer matrix for CNM-polymer nanocomposites. The chemically functionalized CNTs can produce strong interfacial bonds with many polymers, allowing CNT based nanocomposites to possess high mechanical and functional properties. Hence, increased surface adhesion can be measured indirectly by observing increased mechanical properties. However, there is a more direct way to observe interfacial bonds between polymer and CNM by measuring piezoresistivity behavior so that we can imagine the behavior of CNM particles in polymer matrix under deflection. Fuctionalization of MWCNT and rGO was carried out by oxidization reaction of MWCNT and rGO with $H_2SO_4/HNO_3$ solution. Electrical resistivities of MWCNT-PMMA and rGO-PMMA composites were decreased after functionalization because of the destructive fuctionalization process. Meanwhile, piezoresistivities of functionalized CNM-PMMA composites showed more sensitive behavior under the same deflection as compared to pristine CNM-PMMA composites. Therefore, mobility of CNM in polymer matrix was found to be improved with chemical functionalization.