• Applied Chemistry for Engineering
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• v.27 no.3
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• pp.252-258
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• 2016

The weight reduction and improved mechanical property are one of the prime factors to develop new materials for the aerospace industry. Composite materials have thus become the most attractive candidate for aircraft and other means of transportations due to their excellent property and light weight. In particular, fiber reinforced polymer (FRP) composite materials have been used as an alternative to metals in the aircraft. The composite materials have shown improved properties compared to those of metal and polymeric materials, which made the composites being used as the skin structure of the airplane. This review introduces different types of materials which have been developed from the FRP composite material and also one of the most advantageous ways to employ the composites in aircraft.

• Polymer(Korea)
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• v.38 no.2
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• pp.150-155
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• 2014

Polycaprolactone (PCL) is a synthetic biodegradable polymer with excellent mechanical properties. $TiO_2$ (titanium dioxide) has a hydrophilic, high density and excellent biocompatibility. In this work, we produced three-dimensional porous scaffolds with PCL and $TiO_2$ nanoparticles using a salt-leaching method. Physical properties of the scaffolds were analyzed by FE-SEM, FTIR, TGA and compressive strength. Interestingly, the addition of $TiO_2$ nanoparticles decreased the water absorption and swelling ratio of the porous scaffolds. However, the compressive strength was increased by $TiO_2$. CCK-8 assay, which is generally used for the analysis of cell growth, shows that $TiO_2$ nanoparticles have no cytotoxicity. Taken together, we suggest that the PLC/$TiO_2$-scaffold can be used for biomedical applications.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2003.10a
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• pp.134-138
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• 2003

The purpose of this paper is to recycle the fly ash to the valuable resources and settle environment problems which was caused by the fly ash produced from the thermal power plant. Making the fly ash-cement matrix reused fly ash in large quantities, we looked into minutely the physical properties - the elastic modulus, the compressive strength - to increase the usefulness as the building materials for the structure widely. In this paper, the variables are the water-binder(39, 42, 45%), the fine aggregate ratio(37, 41, 45%). Because the fracture energy is influenced by the strength, it is showed to decrease with the increase of W/B and S/a. Besides, we will be able to know that basic properties of the fly ash-cement matrix are similar to that of concrete. But, it is needed to carry out durability experiment on the drying shrinkage, creep, freezing and thawing test to use structural materials.

• Resources Recycling
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• v.8 no.4
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• pp.57-63
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• 1999

Wood-Polymer Composites (WPC) m s prepared irom recycled films of agricullural use and wood wastes, and LLDPE and neal PE resin mlxlurr war also utilized in order to cornpiue the praperlies. Molc~ca nhydride (MA) and dicumyl peroxide were used as an adheslon pmmoler and an il~lliatotor~, .espcmivelyT. ensile prapenies of W Cw zrc measured via lenslle test as a funclieu of woad lille~m d MA contmt, and rractu1.e surface was also mvestigaled wilh SEM. As the content of wwd tiller mcreased, clongauon deneased bul modulus increased However, tensile slrength OI WPC increased only when MA war used, and 1 wt.% of MA may be hgh enough to increase the tensile properties. The tensilc ptopcrlies af WPC prepwed from recycled PE films were &nost same as thosc of neal PE resin mixture.

• Elastomers and Composites
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• v.44 no.3
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• pp.299-307
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• 2009

The effects of reinforcing materials on durability and mechanical properties of V-rib belt were investigated. Cotton fiber and ZnO were used as a filler for CR, and cotton and aramid fiber were used for EPDM rubber compounds. These materials were prepared as a specimen and V-rib belt for heat resistant and mechanical test. High contents of ZnO give improved wear resistance, and higher contents of cotton fiber showed higher durability in high rotation speed but lower wear resistance for CR rubber compounds. Using the aramid and cotton fiber together in EPDM rubber compounds, thermal and wear resistance were improved simultaneously. The material containing EPDM matrix showed better durability and wear resistance than those of containing CR matrix comparing in the same cotton fiber contents.

• Polymer(Korea)
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• v.37 no.6
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• pp.717-721
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• 2013

Biomaterials like silk fibroin (SF) and poly(vinyl alcohol) (PVA) have received increasing attention in biomedical applications because of their attractive properties such as hydrophobicity and biocompatibility. In this study, efficient systems consisting of interpenetrating SF/PVA hydrogels were prepared as potential candidate for wound dressing applications. A simple approach consisting of sonication and a freezing-thawing technique was adopted to fabricate the hydrogels. Different blend ratios consisting of SF (100, 75, 50, 25 and 0%) with respect to the weight of PVA were prepared. The produced hydrogels were characterized for physico-chemical investigations using various states of techniques like; FE-SEM, TGA, FTIR and tensile strength. The addition of PVA to SF was proved to be beneficial in terms of reducing the pore size and swelling ratio of hydrogels. The mechanical property of SF had been increased by addition of PVA. These results show that SF/PVA hydrogels may serve as potential candidates for wound dressing application.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.102-108
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• 2010

The main objective of this study was to evaluate the effect of recycled PET (RPET) fiber made from waste PET bottles to examine application on concrete member. To evaluate the reinforcement effect of RPET fiber in concrete member, experimental tests were performed, such as mechanical property tests (compressive strength, modulus of elasticity and splitting tensile strength) and drying shrinkage test. In mechanical property tests, compressive strength and modulus of elasticity in concrete mixed with RPET fiber gradually decreased, but splitting tensile strength gradually increased as volume fraction of fiber increased. In drying shrinkage test, free drying shrinkage increased. In restrained case, in contrast, crack occurrence was delayed because of tensile resistance increase by RPET fiber. The comparison of RPET and PP fiber added concrete specimen's properties showed that two materials had similar properties. In conclusion, RPET fiber is an alternative material of PP fiber, even finer for its excellence in eco-friendliness due to the recycling of waste PET bottles and its possible contribution to the pollution declination.

• Composites Research
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• v.34 no.1
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• pp.16-22
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• 2021

Polyurethane foam (PUF) can be manufactured in soft, semi-rigid, and hard forms, so it is used in various fields industrially. Among them, rigid PUF has excellent mechanical properties and low thermal conductivity, and is used as a thermal insulation material for buildings and as a cold insulation material in the natural gas transportation field. In this field, there is a steady demand on higher mechanical strength and lower thermal conductivity. In this study, a rigid PUF was manufactured, and the microstructure and physical properties were studied according to the impeller type (propeller, dispersed turbine) of the agitator. Through FE-SEM and Micro-CT analysis, it was confirmed that the average pore size of the foam manufactured with the dispersed turbine was 21.5% smaller than that of the pore made by the propeller. The compressive strength was improved by 15.4%, and the thermal conductivity decreased by 3.1% in the foam with small pores. This result can be utilized for fabricating PUF composites.

• Composites Research
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• v.35 no.3
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• pp.182-187
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• 2022

In this paper, the thickness of a multilayer PCB was predicted through an empirical formulation based on the physical properties of the prepreg used in multilayer PCB. Since the thickness of prepreg reduction when manufacturing a PCB due to the physical properties and copper foil residual rate, it is necessary to accurately predict the thickness of the PCB through the thickness empirical formulation. To determine the density of the prepreg, the mass and thickness of the prepreg were measured. To manufacture the CCL, the prepreg and copper foil were laminated using a hot press machine, and the thickness was measured using a microscope and micrometer. An 8-layerd PCB was designed with different circuit densities to measure the change in the thickness with the copper foil residual ratio, and the proposed empirical formulation was verified by comparing the measured thickness with the value obtained using the empirical formulation. As a result, the errors for the CCL and multilayer PCB were 2.56% and 4.48%, respectively, which demonstrated the reliability of the empirical formulation.

• Composites Research
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• v.21 no.6
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• pp.1-7
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• 2008

The main objective of this study is to investigate the effect of salt water on the mechanical properties of a high modulus carbon-epoxy composite. Specimens were made of a carbon-epoxy composite UPN139B of SK Chemical and tested under inplane tension and shear after 0, 1, 3, 6, 9, and 12 months immersion in 3.5% salt water. Acceleration technique such as temperature elevation was not used. The tensile strengths and modulli in fiber and matrix direction did not show any remarkable degradation until 12 months immersion. In contrast to the tensile properties, shear strength and modulus started to gradually decrease up to about 10% of values of dry specimens after 12 months immersion. It was confirmed through the test that the material UPN139B can be an effective material for the shell structures in salt water to resist against the external pressure buckling because of the high fiber directional modulus and corrosion resistance.