• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.20 no.4
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• pp.248-255
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• 2010

Airborne nanoparticle concentrations in three metrics (particle surface area concentration, particle number concentration, and particle mass concentrations) were measured by task in a laboratory making carbon nanotubes (CNTs) films using three direct reading instruments. Because of the conducted other researcher's experiment before the tasks, airborne nanoparticle surface area and number concentrations are the highest at the first time conducted weighing and mixing by sonication task, respectively. Because of the mist generated during mixing by sonication, the highest airborne nanoparticle surface area and PM1 concentrations were measured in the task among the total. Nanoparticle surface area concentrations at the researchers' breathing zones had high correlation (r=0.93, p<0.01) with those measured at an area in the laboratory. This result indicates that nanoparticles generated during the experiment contaminated the whole room air. When the experiment performed all the fume hoods weren't operated and making CNTs films task were conducted in the out of the fume hoods. In conclusion, researchers performing making CNTs film experiments were exposed to airborne nanoparticles generated during the experiment without adequate controls. We recommend that adequate controls should be implemented so that workers' exposures to airborne nanoparticle are limited to minimum levels.

• Polymer(Korea)
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• v.24 no.2
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• pp.220-227
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• 2000

Silica and carbon black filled natural rubber (NR) vulcanizates were prepared with different mixing modes and amounts of fillers. Curing characteristics, morphology. and tear properties of the NR vulcanizates were investigated. The NR vulcanizates filled with silica and carbon black sequentially showed longer induction time ($t_2$), cure index ($t_{90}$ ), and lower maximum torque ($T_{max}$ ) than the NR vulcanizates filled with them simultaneously, during curing process. The former showed superior dispersion of fillers and tear properties to the latter. The NR vulcanizates containing 30 phr of silica showed excellent properties in the experimental range.

• Macromolecular Research
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• v.16 no.3
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• pp.261-266
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• 2008

A variety of end-functionalized polymers were grafted spontaneously onto multi-walled carbon nano-tubes (MWNTs) using a solution mixing process. The end-functional groups of the polymers underwent noncovalent grafting to the defect sites at the surface of the purified MWNTs through zwitterionic interaction or hydrogen bonding. The physically grafted polymers including polystyrene (PS), poly(methyl methacrylate) (PMMA), polyethylene oxide (PEO), and polydimethylsiloxane (PDMS) provided sufficient compatibility with an organic solvent or polymer matrix, such that the nanotubes could be finely dispersed in various organic media. This approach is universally applicable to a broad range of polymer-solvent pairs, ensuring highly dispersed carbon nanotubes through simple solution mixing.

• Elastomers and Composites
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• v.45 no.2
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• pp.80-86
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• 2010

Carbon nanotubes (CNTs) exhibit excellent mechanical, electrical, and magnetic properties as well as nanometer scale diameter and high aspect ratio, which make them an ideal reinforcing agent for high strength polymer composites. The functionalized CNTs are believed to be very promising in the fields such as preparation of functional and composite materials. CNT-Polymer composites are expected to have good processability characteristics of the polymer and excellent functional properties of the CNTs. However, since CNTs usually form stabilized bundles due to Van der Waals interactions, are extremely difficult to disperse and align in a polymer matrix. The biggest issues in the preparation of CNT-reinforced composites reside in efficient dispersion of CNTs into a polymer matrix, and the alignment and control of the CNTs in the matrix. There are several methods for the dispersion of nanotubes in the polymer matrix such as solution mixing, bulk mixing, melt mixing, in-situ polymerization and chemical functionalization of the carbon nanotubes, etc. These methods and preparation of high performance CNT-polymer composites are described in this review.

• Resources Recycling
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• v.16 no.6
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• pp.10-19
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• 2007

The mechanical process followed by hydrometallurgical treatment has been developed in order to recover cobalt and lithium from spent lithium ion battery. In the previous study, a citrate precursor combustion process to prepare cathodic active materials from the leaching solution was elucidated. Resynthesis of electrode materials should be more valuable in spent battery recycling. Conventional slurry mixing of $LiCoO_2$ and carbon cannot make uniform distribution, and therefore the cathode cannot reach the theoretical charge-discharge capacity and is easily degraded during the charge-discharge cycling. In this study, ultra-fine $LiCoO_2$ powders has been prepared by modification of the combustion process and fabricated the enhanced cathode by modification of mixing method of $LiCoO_2$ and carbon added.

• Elastomers and Composites
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• v.39 no.1
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• pp.51-60
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• 2004

The cure, viscoelastic and mechanical characteristics of organoclay filled NR/BR blends were studied and compared with the properties of carbon black and silica filled NR/BR blends. The nanocomposites with extensive exfoliation state can be fabricated by a solution mixing method. In the composites, the amount of filler content was fixed to 10 phr. Degree of intercalation and exfoliation was characterized by X-ray diffraction (XRD). XRD results indicated exfoliation of the silicate layers into the rubber matrix. While the degree or intercalation and exfoliation is lowered by the conventional mixing method, extensive exfoliation can be obtained by the solution mixing method. It was found that the clay filled NR/BR compound showed better viscoelastic (tan ${\delta}$) and mechanical properties than the carbon black or silica filled NR/BR compounds.

• Carbon letters
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• v.12 no.1
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• pp.53-56
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• 2011

This study aimed to investigate the influence of mesoporous carbons on the thermal insulation properties of epoxy/mesoporous carbon composites. The mesoporous carbon (CMK-3) was prepared by conventional templating method using SBA-15. The epoxy/mesoporous carbon composites were prepared by mixing the synthesized CMK-3 with diglycidylether of bisphenol A (DGEBA). As experimental results, the curing reactivities of the DGEBA/CMK-3 composites were found to decrease with the addition of the CMK-3. Also, the thermal conductivities of DGEBA/CMK-3 composites were found to decrease with increasing CMK-3 content. This could be interpreted in terms of the slow thermal diffusion rate resulting in pore volume existing in the gaps in the interfaces between the mesoporous carbon and the DGEBA matrix.

• Journal of Korean Society for Atmospheric Environment
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• v.31 no.2
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• pp.173-180
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• 2015

The purpose of this study was to fabricate a ferric nitrate impregnated activated carbon, and the performance for hydrogen sulfide by adsorption was evaluated. Sodium hydroxide was utilized to control pH in the process during generation of ferric hydroxide on the surface of the carbon. Critical mixing duration for generation of ferric hydroxide on the carbon was 48 hrs at pH 1 of the solution, in which the chemical adsorption of hydrogen sulfide was enhanced. The adsorption capacity of the impregnated carbon increased up to 0.10 g hydrogen sulfide/g carbon, which was 4.3 times higher than that of the raw carbon. Presence of FeOOH on the surface of the impregnated carbon was examined by X-ray diffraction.

• Carbon letters
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• v.8 no.4
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• pp.335-339
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• 2007

Carbon/silicon composites were synthesized by mixing silicon powders with petroleum pitch and subsequent heat-treatment. The resultant composites were composed of carbon and nano-size crystalline silicon identified by XRD and EDX. FIB images and SEM images were taken respectively to detect the existence of silicon impregnated in carbon and the distribution of silicon on the carbon surface. The obtained carbon/silicon materials were assembled as half cell anodes for lithium ion secondary battery and their electrochemical properties were tested. The pitch/silicon composite (3 : 1 wt. ratio) heat treated at $1000^{\circ}C$ and mixed with 55.5 wt.% of graphite showed relatively good electrochemical properties such as the initial efficiency of 78%, the initial discharge capacity of 605 mAh/g, and the discharge capacity of 500 mAh/g after 20 cycles.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.4
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• pp.511-517
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• 2011

To evaluate carbon emission in water treatment processes, LCA (life cycle assessment) was applied to 8 multi-regional water treatment plants (WTPs) from intake to supply of tap water. Investigation of 8 WTPs revealed that average carbon emission for 1 $m^3$ of tap water was 221 g. Major carbon emission sources in water supply system were intake and supply processes. Meanwhile, mixing process was the main carbon emission source in unit water treatment processes. Carbon emission was proportional to the turbidity and COD of raw water. Intake of better raw water and minimization of energy consumption in unit processes are needed to reduce carbon emission in the WTPs. In addition, comparison of carbon emission among WTPs can be used as a parameter for optimization of operation and maintenance of water treatment processes.