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CFRTP
Advanced CFRTP forming technology
Owing to the many advantages of carbon fiber, such as its high strength, good electrical conductivity, and light weight, carbon fiber-reinforced thermoplastics (CFRTPs) have been used in a variety of applications. However, the use of CFRTPs in fabrics suffers a significant drawback regarding their manufacture. The molten viscosity of thermoplastic resins is extremely high compared to that of thermoset resins, which makes it difficult to impregnate thermoplastic resin into fiber bundles. In addition, thermoplastic resins exhibit poor interfacial adhesion with carbon fibers because of low surface energy and a chemically inert surface. Therefore, We are developing the carbon fiber surface treatment methods and CFRTP manufacturing process to improve the interfacial adhesion and the degree of impregnation.
SH Han, HJ Oh, SS Kim. Evaluation of the impregnation characteristics of carbon fiber-reinforced composites using dissolved polypropylene. Composites Science and Technology. 2014; 91:55–62
PP sized carbon fiber
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ADHESIVE JOINT
Design of adhesive joints at cryogenic environment
A cryogenic containment system to prevent leakage of liquefied natural gas on carrier ships is composed of a primary barrier, insulation foam, and secondary barriers. Because the stainless steel metallic barriers in cryogenic containment systems must be joined together, the development of reliable joining technology at low temperatures or in harsh environments is important because the joint is generally the weakest part in the assembled structure. Epoxy resins are generally employed as the basis for adhesive components because they have many useful engineering properties, such as a high modulus, high failure strength, low creep, and good performance at elevated temperatures. However, epoxy resins are quite brittle, with poor resistance to crack initiation and propagation in cryogenic environments. Because of this, adhesives used in cryogenic systems need to be reinforced to increase their fracture toughness. In this study, we are developing the homogenous core–shell structured nanofibers with an epoxy matrix in the shell to achieve a substantial increase in the wettability, toughness, and mechanical properties of the adhesive at cryogenic temperature of −150 °C.
HJ Oh, SH Han, HY Kim, SS Kim. The influence of the core-shell structured meta-aramid/epoxy nanofiber mats on interfacial bonding strength and the mechanical properties of epoxy adhesives at cryogenic environment. Journal of Adhesion Science and Technology. 2014;28:950–962.
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SMART MATERIALS
Fabrication of microcellular phenolic foams by using microwave technology
Polymer foams can be used as thermal insulation and weight reduction in multiple fields, such as buildings, automobiles, and LNG containment systems. Especially, phenolic foams are preferred as a thermal insulator due to a lower flammability and lower gas generation than other polymeric insulation foams. Conventional foaming methods require the extensive time to fabricate the large volumes and environmental regulations limit the use of blowing agents. To tackle these issues, we are developing the nanoparticle reinforced microcellular phenolic foams to improve the mechanical and thermal properties of the foams by microwave method in a short time.
S.A.Song, H.J.Oh, B.G.Kim, S.S.Kim, Novel foaming methods to fabricated carbon reinforced microcellular phenolic foams, Composites Science and Technology, 2013;76:45-51.
Microcellular phenolic foam
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STRUCTURAL DESIGN
Structural design with composite materials
The global auto industry has made advances in the improvement of driveline efficiency and in the lightweight development of structures, increasingly using carbon fiber-reinforced composites (CFRPs) to achieve modest weight savings. Therefore, we have tried to realistically describe the static and dynamic behaviors of CFRP automobile parts through the use of appropriate mathematical models and computer simulation analyses.
HC Lee, YS Jung, HJ Oh, SS Kim, The design of a hybrid composite strut tower for use in automobiles. Advanced Composite Materials. 2014
The stress distribution in the hybrid composite strut tower
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