• Composites Research
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• v.33 no.1
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• pp.19-24
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• 2020

In this paper, the microwave irradiation process was conducted during the Poly(vinylidene fluoride) (PVDF) nano-composite film fabrication process to analyze how the β-crystalline is increased. TiO₂ was added as a nanoparticle reinforcement to further improve the β-crystalline conformation of the PVDF films by van der Waals force due to the difference of electronegativity between PVDF and the metal oxide nanoparticle. The crystalline conformation of the fabricated films was analyzed by X-ray diffraction and Fourier transform infrared spectroscopy. According to these analysis results, it was confirmed that the microwave irradiation process during the solvent evaporation process increases the crystallinity of the PVDF films, and more β-crystalline can be obtained after additional film stretching process. It was also found that the PVDF nano-composite films with the metal oxide have relatively higher β-crystalline conformation rather than the neat PVDF films.

• Journal of Powder Materials
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• v.8 no.3
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• pp.163-167
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• 2001

A bulk porous $CaZrO_3/MgO$ composite with plantinum nano-dispersion was synthesized in air atmosphere through the combination of several in situ reactions, including the pyrolysis of $PtO_2$. A mixture of $CaMg(CO_3)_2$(dolomite), $ZrO_2$, $PtO_2$ and LiF (0.5 wt%, as an additive) was cold isostatically pressed at 200 MPa and sintered at $1100^{\circ}C$ for 2 h. The porous $CaZrO_3/MgO/Pt$ composite ($CaZrO_3/MgO$ : Pt=99 : 1 in volume) had a uniformly open-porous structure (porosity: 56%) with three-dimensional (3-D) network and a narrow pore-size distribution, similarly to the porous $CaZrO_3/MgO$ composites reported before. Catalytic Properties (viz., NO direct decomposition and NO reduction by $C_2H_4$) of the $CaZrO_3/MgO/Pt$ composite were investigated up to $900^{\circ}C$. In the absence of oxygen, the NO conversion rate reached ~52% for the direct decomposition and ~100% for the reduction by $C_2H_4$, respectively. The results suggest the possibility of the porous composite as a multifunctional filter, i.e., simultaneous hot gas-filtering and $de-NO_x$ in one component.

• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.842-845
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• 2005

Glass composites containing ceramic fiber have been developed for Solid Oxide Fuel Cell (SOFC) seals. Effect of glass type, loading pressure and thermal cycle the leak rates of composite seals was investigated. Seal performance of two commercial glasses was compared with that of $SiO_2BaO-B_2O_3$ glass synthesized in this work. The leak rate for seals made of pyrex(R) increases from $\~0.0005\;to\;\~0.004sccm/cm$ as the gas pressure increases from 10 to 50 kPa. The soda lime silicate glass seal shows the leak rate two times higher than the one made of pyrex(R) or $SiO_2BaO-B_2O_3$ glass. The viscosity of glass at the seal test temperature is presumed to affect the leak rate of the glass seal. As the applied loading pressure increases from 0.4 to 0.8 MPa at $750^{\circ}C$, the leak rate decreases from 0.038 to 0.024 sccm/cm for composite seals. It has been found that during 50 thermal cycles between $450^{\circ}C\;to\;700^{\circ}C$ leak rates remained almost constant, ranging from 0.025 to 0.03sccm/cm. The results showed an excellent thermal cycle stability as well as sealability of the glass matrix ceramic fiber composite seals.

• Elastomers and Composites
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• v.47 no.3
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• pp.188-193
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• 2012

The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Recently, the design, analysis and evaluation technology was required to achieve the high quality, fidelity, reliability of rubber products. However, rubber manufacturing companies of our country have uesd the method of trial and error and experience in the process of a compound mixing, manufacturing and improvement of rubber properties. The objectives of this study are to establish the test methods of rubber material and to make the database of rubber material properties and to evaluate the performance of rubber components and to construct the prediction system of fatigue life. Fatigue lifetime prediction methodology of the rubber component was proposed by incorporating the finite element analysis and fatigue damage parameter from fatigue test.

• Elastomers and Composites
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• v.44 no.2
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• pp.106-111
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• 2009

Tissue engineering is a research field for artificial substitutes to improve or replace biological functions. Scaffolds play a important role in tissue engineering. Scaffold porosity and pore size provide adequate space, nutrient transportation and cell penetration throughout the scaffold structure. Scaffold structure is directly related to fabrication methods. This review will introduce the current technique of 3D scaffold fabrication for tissue engineering. The conventional technique for scaffold fabrication includes salt leaching, gas foaming, fiber bonding, phase seperation, melt moulding, and freeze drying. These conventional scaffold fabrication has the limitations of cell penetration and interconnectivity. In this paper, we will present the solid freeform fabrication (SFF) such as stereolithography (SLA), selective laser sintering (SLS), and fused deposition modeling (FDM), and 3D printing (3DP).

• Elastomers and Composites
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• v.44 no.4
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• pp.401-407
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• 2009

Commercial grades of solution styrene-butadiene rubbers extended with high aromatic oils having high polycyclic aromatic compounds (PCA) and low PCA oils were used to study the effect of the processing oil particularly on the crack propagation resistance and frictional wear resistance of the vulcanizates. The aromatic oil based vulcanizates exhibited superior fracture behavior over the low PCA oil extended vulcanizates based on tensile and trouser tear tests. Compounds with aromatic oil showed superior crack propagation resistance compared with those containing low PCA oil, especially at the lower ranges of tearing energy. In terms of frictional wear resistance, the aromatic oil extended compounds showed superior performance particularly in the lower frictional work ($W_f$) range but in the higher $W_f$ range the low PCA oil extended vulcanizates performed better.

• Composites Research
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• v.33 no.2
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• pp.55-60
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• 2020

A study on the heating behavior and adhesion property of structural epoxy adhesive through induction heating have been conducted. An adhesive for induction heating was manufactured through mixing with nano and micro sized Fe₃O₄. From the results, it was observed that induction heating is less affected by adherend (GFRP) thickness than oven heating. The heating rate of Fe₃O₄ embedded epoxy adhesive using induction heating much higher than that of oven curing process and it is more appreciable when the contents of Fe₃O₄ increased. Furthermore, adhesion strength increased with increase of Fe₃O₄ particle contents.

• Elastomers and Composites
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• v.48 no.1
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• pp.18-23
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• 2013

Nylon 12 elastomer was slightly crosslinked in molten state by the addition of small amount of dicumyl peroxide (DCP) as a crosslink agent and triallycyanuate (TAC) as a co-agent during melt compounding at $160^{\circ}C$ in an internal mixer. The effect of the peroxide crosslinking on mechanical, dynamic mechanical and rheological properties of the nylon 12 elastomer was investigated by means of tensile testing, dynamic mechanical analysis (DMA) and small amplitude oscillating rheometer, respectively. With modification, there is an improvement in tensile modulus and Young's modulus with decease in elongation at break. DMA results for peroxide modified nylon 12 elastomers demonstrated that the glass transiaiton temperature of PTMG segment shifted to higher temperature and the storage modulus remained constant above the melting temperature of nylon 12 segments. Melt rheological studies revealed that the peroxide modified nylon 12 elastomer exhibited a more solid like behavior and stronger shear thinning behavior compared to neat nylon 12 elastomer, which was more prominent at higher TAC content in the polymer matrix. The peroxide modified nylon 12 elastomer exhibited good elastic recoverability and improved mechanical properties without sacrificing melt processibilty, and especially the service temperature range increased as compared to neat nylon 12 elastomer.

• Elastomers and Composites
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• v.45 no.1
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• pp.40-43
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• 2010

In this study, polyimide(PI) nanofibers mats were prepared by electrospinning and three different fiber morphologies of random, uniaxial, and biaxial orientation were prepared by controlling the speed of drum-shaped collector and other parameters. The SEM studies reveal that the aforesaid morphologies were obtained on the nano-fibrous mats prepared. The ionic conductivity was measured using an in-plane type conductivity tester for the PI mats soaked in the mixture of 1M lithium trifluoro-methane-sulfonate and tetra-ethylene glycol dimethyl ether. The ionic conductivity was surprisingly higher for the biaxial PI mats. For the uniaxially-oriented mats, the ionic conductivity was found to be higher in the parallel direction compared to the perpendicular direction of the fiber orientation. A curious cyclic fluctuation was found in the ionic conductivity with time. The observed behavior was explained by considering the distance between fibers and transport speed of ions used in this study.

• Composites Research
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• v.19 no.6
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• pp.23-31
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• 2006

We measured mechanical properties, including Young's modulus, effective bending modulus and nominal fracture strength of nanohoneycomb structures using an Atomic Force Microscope(AFM) and a Nano-Universal Testing Machine(UTM). Anodic aluminum oxide(AAO) films are well suited as nanohoneycomb structures because of the simple fabrication process, high aspect ratio, self-ordered hexagonal pore structure, and simple control of pore dimensions. Bending tests were carried out for cantilever structures by pressing AFM tips, and the results were compared with three-point bending tests and tensile tests using a Nano-UTM. One side of the AAO films is clogged by harrier layers, and looks like a face material of conventional sandwich structures. Analysis of this layer showed that it did not influence the bending rigidity, and was just a crack tip. The present results can act as a design guideline in applications of nanohoneycomb structures.