Byung-Gak Min

Effects of functional grafting on viscoelastic and toughness behaviors of multi-walled carbon nanotubes-reinforced polypropylene nano-composites

Abstract

Production of graphene oxide from pitch-based carbon fiber

Pitch-based graphene oxide (p-GO) whose compositional/structural features are comparable to those of graphene oxide (GO) was firstly produced by chemical exfoliation of pitch-based carbon fiber rather than natural graphite. Incorporation of p-GO as nanofillers into poly(methyl methacrylate) (PMMA) as a matrix polymer resulted in excellent mechanical reinforcement. p-GO/PMMA nanocomposite (1 wt.-% p-GO) demonstrated 800% higher modulus of toughness of neat PMMA.

Effects of cross-linking methods for polyethylene-based carbon fibers: review

In recent decades, there has been an increasing interest in the use of carbon fiber reinforced plastic (CFRP) in aerospace, renewable energy and other industries, due to its low weight and relatively good mechanical properties compared with traditional metals. However, due to the high cost of petroleum-based precursors and their associated processing costs, CF remains a specialty product and as such has been limited to use in high-end aerospace, sporting goods, automotive, and specialist industrial applications. The high cost of CF is a problem in various applications and the use of CFRP has been impeded by the high cost of CF in various applications. This paper presents an overview of research related to the fabrication of low cost CF using polyethylene (PE) control technology, and identifies areas requiring additional research and development. It critically reviews the results of cross-linked PE control technology studies, and the development of promising control technologies, including acid, peroxide, radiation and silane cross-linking methods.

Influence of Nitrogen moieties on CO 2 capture of Carbon Aerogel

Carbon aerogel is a porous carbon material possessing high porosity and high specific surface area. Nitrogen doping reduced the specific surface area and micropores, but it furnished basic sites to improve the CO2 selectivity. In this work, N-doped carbon aerogels were prepared with different ratios of resorcinol/melamine by using the sol-gel method. The morphological properties were characterized by scanning electron microscopy (SEM). Nitrogen content was studied by X-ray photoelectron spectroscopy (XPS) and the specific surface area and micropore volume were analyzed by N2 adsorption-desorption isotherms at 77 K. The CO2 adsorption capacity was investigated by CO2 adsorption-desorption isotherms at 298 K and 1 bar. Melamine containing N-doped CAs showed a high nitrogen content (5.54 wt.%). The prepared N-doped CAs exhibited a high CO2 capture capacity of 118.77 mg/g (at resorcinol/melamine = 1:0.3). Therefore, we confirmed that the CO2 adsorption capacity was strongly affected by the nitrogen moieties.

Highly Efficient Visible Blue-Emitting Black Phosphorus Quantum Dot: Mussel-Inspired Surface Functionalization for Bioapplications

The preparation of blue-emitting black phosphorus quantum dots (BPQDs) is based on the liquid-phase exfoliation of bulk BP. We report the synthesis of soluble BPQDs showing a strong visible blue-light emission. Highly fluorescent (photoluminescence quantum yield of ≈5% with the maximum emission (λmax) at ≈437 nm) and dispersible BPQDs in various organic solvents are first prepared by simple ultrasonication of BP crystals in chloroform in the ambient atmosphere. Furthermore, simple mussel-inspired surface functionalization of BPQDs with catechol-grafted poly(ethylene glycol) in basic buffer afforded water-soluble blue-emitting BPQDs showing long-term fluorescence stability, very low cytotoxicity, and excellent fluorescence live cell imaging capability.

Carbon Fibers (I): General Understanding and Manufacturing Techniques of Carbon Fibers

Carbon fibers are a new breed of high-strength materials which have been described as a fiber containing at least 90% carbon obtained by the controlled pyrolysis of appropriate fibers. Carbon fiber composites are ideally suited to applications where strength, stiffness, lower weight, and outstanding fatigue characteristics are critical requirements. They also can be used in the occasion where high temperature, chemical inertness and high damping are important. In recent decades, carbon fibers have found wide applications in commercial and civilian aircraft, recreational, industrial, and transportation markets. Therefore, understanding the basic structure, synthesis and physicochemical properties of carbon fibers is very important to apply them as a precursor of above applications. This review paper discuss the general information and manufacture technique of carbon fibers used for improving the performance of composite materials in various industries for the present.

Preparation of stable dispersions of chemically reduced graphene oxide through noncovalent interactions with poly(N-isopropyl acrylamide)-grafted pluronic copolymer

Stable dispersions of chemically reduced graphene oxide (RGO) were prepared by simple noncovalent interaction with poly(N-isopropyl acrylamide) (PNIPAAm)-grafted Pluronic (NGP). Prepared NGP/RGO assembly solutions showed temperature-dependent optical absorbance change below or above their lower critical solution temperature (LCST). Interestingly, LCSTs of NGP/RGO assemblies were unaffected compared with LCSTs of pristine NGPs regardless of the degree of PNIPAAm grafting in NGPs probably because noncovalent anchoring between PNIPAAm chains and RGO plates in NGP/RGO assembly is weak. This supports that PNIPAAm grafting on Pluronic occurred preferentially in hydrophilic PEO segments because hydrophobic PPO segments of NGP must be strongly anchoring on hydrophobic surface of RGO plates while PEO segments will be extended from RGO surface to aqueous medium.

Carbon Fibers (II): Recent Technical Trends and Market Prospects of Carbon Fibers

The principal aims of the review paper are (1) to establish broad overview information, both qualitative and quantitative, relating to the world market for polyacrylonitrile (PAN) or pitch-based carbon fibers; and (2) to generate an effective analysis and break down of consumption by process route and eventual end-use. The review paper also designed specifically to provide subscribers with an accurate, independent, and realistic assessment of the current status and future perspective of the market for carbon fibers in the world. The world market for carbon fibers continues to grow rapidly, fuelled by new industrial end uses, such as sport and leisure goods, aerospace, automotive applications, civil engineering and infrastructure repair, and immerging applications in energy generation. Demands for properties of carbon fibers used in those applications include many things such as strength, toughness, fatigue property, corrosion resistance, heat resistance, etc., and these become to be higher level. On the other hand, demands for manufacturing technologies of carbon fibers become to be difficult with these demands for properties, and these are wide variety such as high efficiencies, high qualities, many functions, labor saving, and low cost. In this review paper, thus, the recent carbon fibers corresponded to these needs, and its latest manufacturing technologies as well as market prospects are described.

Visible-light-driven photocatalysis with dopamine-derivatized titanium dioxide/N-doped carbon core/shell nanoparticles

Titanium dioxide/N-doped carbon core/shell nanoparticles enabling efficient visible-light-driven photocatalytic degradation of rhodamine B, considered a model compound for water-soluble environmental pollutants, were successfully prepared by the carbonization of dopamine-grafted TiO2 nanoparticles. These precursor nanoparticles were prepared via simple ligand-to-metal charge transfer (LMCT) between TiO2 nanoparticles and dopamine. Owing to the incorporation of Ti–O–C chelating bonds and the subsequent narrowing of the optical band gap, the dopamine-derivatized photocatalyst demonstrated enhanced activity compared with that of commercial photocatalysts and promoted the photocatalytic degradation of rhodamine B under both UV light and visible light. This LMCT-mediated incorporation of thin amorphous N-doped carbon shells onto the surface of semiconducting photocatalysts may be widely applicable for the generation of novel and robust hybrid materials with enhanced photocatalytic activities for many applications.

Filler-Elastomer Interactions: Effect of Ozone Treatment on Adhesion Characteristics of Carbon Black/Rubber Composites

ABSTRACT In this work, the changes in surface and adhesion characteristics of carbon black/rubber compoundings treated by ozone technique are investigated in different treatment times. The surface properties of carbon blacks are studied by contact angle measurement and their adhesion characteristics are determined by crosslinking density and tearing energy (G IIIC ) of the composites. As a result, it is found that the increasing of the ozone treatment time leads to an increase of the introduction of oxygen-containing functional groups onto carbon black surfaces and to an increase of the polar component ( ys SP ) of surface free energy ( ys ), resulting in improving the crosslink density and tearing energy (G IIIC ) of the composites. The results can be explained by the fact that the polar functional groups of carbon black surfaces by the treatment lead to an increase of the adhesion at interfaces between carbon blacks and polar rubber matrix.