• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.10a
• /
• pp.133-136
• /
• 2001

The effect of pre-carbonization condition on the mechanical properties of nonwoven needle-punched carbon/phenolic composite was studied. The nonwoven Oxi-PAN felt was pre-carbonized at different temperature. The pre-carbonized Oxi-PAN felt was needle-punched and then carbonized. Needle-punched nonwoven carbon preforms were formed into composites with phenol resin. The tensile and flexural strengths showed maximum value with pre-carbonization temperature of $500^{\circ}C$. Compared with the non-pre-carbonized composite, the mechanical properties were slightly improved.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1136-1139
• /
• 2005

As alternative materials for bipolar plate of PEM Fuel Cells, carbon composites were fabricated by compression molding. In this study, four types of nano particles, such as Carbon nanotubes, Carbon black, GX-15 and P-15 were mixed with epoxy resin to provide electric conductivity and structural properties. By increasing pressure during molding and volume ratio of nano particles, the physical contact among particles was improved resulting in increased electric conductivity. Surface resistance test showed, P-15 particles have the highest electric conductivity.

• Carbon letters
• /
• v.2 no.3_4
• /
• pp.165-169
• /
• 2001

Modification of C/C composite bipolar plate for improving electrical conductivity was carried out by addition of electroconductive carbon black (EC-CB). Carbon black was carefully mixed to methanol-containing phenolic resin, impregnated into 2D-carbon fabrics, hot pressed and then carbonized to obtain composite plate. Inclusion of electro-conductive carbon black enhanced the electrical conductivity of the C/C composites by increasing the conduction path. Addition of 10 vol% carbon black increased the electrical conductivity from 5.5/${\Omega}cm$ to 32/${\Omega}cm$ and reduced the crack formation by filling effect, resulting in the increase of flexural properties of composite plate. However, at carbon black content over 10 vol%, flexural properties decreased by delaminating role of excess carbon black at the interface in C/C composites.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.292-295
• /
• 2004

Recently, polymer-clay hybrid materials have received considerable attention from both a fundamental research and application point of view. This organ-inorganic hybrid, which contains a nanoscale dispersion of the layered silicates, is a material with greatly improved thermal and mechanical characteristics. Two classes of nanocomposites were synthesized using an unsaturated polyester resin as the matrix and sodium montmorillonite as well as an organically modified montmorillonite as the reinforcing agents. X -ray diffraction pattern of the composites showed that the interlayer spacing of the modified montmorillonite were exfoliated in polymer matrix. The mechanical properties also supported these findings, since in general, tensile strength, modulus with modified montmorillonite were higher than the corresponding properties of the composites with unmodified montmorillonite. Adding organically modified clay improved the tensile strength of unsaturated polyester by $22\%$ and the tensile modulus of unsaturated polyester was also improved by $34\%$.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.4 no.2
• /
• pp.173-182
• /
• 1996

An analytical model has been developed to predict the elastic properties of a filled resin reinforced by chopped fibers, a three-phase composite such as a filled sheet molding compound(SMC). In the model the matrix material and fillers form an effective matrix. The effective matrix is then considered to be reinforced with long fibers lying in the sheet plane but randomly oriented in the plane. Expressions for the resulting transversely isotropic composite properties are explicitly presented. Using this model, the Young's and shear moduli are calculated for the SMC sample with filler weight fraction of 35% and fiber content of 30%. The same properties are also determined experimentally. The agreement between the calculated and measured elastic moduli is found to be very good for the in-plane properties. However, the out-of-plane properties show a large difference because the effect of voids is not taken into account in the model.

• Journal of Environmental Science International
• /
• v.22 no.6
• /
• pp.687-694
• /
• 2013

To investigate organoclay, high styrene resin masterbatch (HSR), high impact polystyrene (HIPS), and polystyrene (PS) as reinforcing materials for the improvement of the abrasion resistance of poly(styrene-block-butadiene-block-styrene) (SBS), SBS/organoclay nanocomposites, SBS/HSR, SBS/HIPS, and SBS/PS blends were prepared. The effect of organoclay and blends on the abrasion resistance and mechanical properties of SBS was investigated. Even though intercalations of organoclay are observed for SBS/Cloisite 20A nanocomposites and not for SBS/Cloisite 30B composites, the abrasion resistance of SBS/Cloisite 20A nanocomposites is worse than that of SBS/Cloisite 30B composites. When SBS was blended with HSR, HIPS and PS, the abrasion resistance of the blends increases with increasing of HSR, HIPS and PS content from 0 to 20 wt%.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.349-352
• /
• 2006

Pull-off test is generally used as a method of evaluating bond strength of FRP with concrete at the job site. However, pull-off test damages FRP composites and the maximum pull-off strength is limited up to tensile strength of concrete. Accordingly, it is required to set-up a test method that can simply evaluate bond performance of structural adhesive. This study suggested compression and bending test of epoxy resin as test methods that can indirectly evaluate performance of adhesive, as well as standardized test specification for different types of specifications from various countries. In this study, the section dimension of compression and bending test specimens is unified, and standard test specimen size is achieved by test results.

• Journal of the Korean Ceramic Society
• /
• v.33 no.8
• /
• pp.935-941
• /
• 1996

Two-dimensional carbon/carbon preforms made of PAN-based carbon yarn and phenolic resin were densified with pyrolysis of propane by pulse chemical vapor infiltration where repeated the cycle of gas introduction residence and evacuation. Maximim density increment was 14% when infiltration temperature and time were 100$0^{\circ}C$ and 21.25 hrs respectively. The distribution of deposits of pyrocarbon by this process has been occurred uniformly in the bottom middle and top of carbon/carbon composite preform Pulse CVI with residence is most effective in increasing density and shortening infiltration time among isothermal CVI and pulse CVI with and without residence.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.285-286
• /
• 2008

Recently, epoxy based nano-composites are being increasingly investigated for their electrical properties, since the introduction of nano fillers demonstrate several advantages in their properties when compared with the similar properties obtained for epoxy systems with micrometer sized fillers. We calculated scale and shape parameter using dielectric strength. In this paper, it is investigated that the allowable' breakdown probability of specimens is stable at some value using Weibull statistics. Therefore we found that breakdown probability of specimens is stable until 20 [%].

• Carbon letters
• /
• v.10 no.2
• /
• pp.97-100
• /
• 2009

In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.