Heat resistance of carbon nanoonions by molecular dynamics simulation

Wang, Xianqiao,Lee, James D. Techno-Press 2011 Interaction and multiscale mechanics Vol.4 No.4

Understanding the structural stability of carbon nanostructure under heat treatment is critical for tailoring the thermal properties of carbon-based material at small length scales. We investigate the heat resistance of the single carbon nanoball ($C_{60}$) and carbon nanoonions ($C_{20}@C_{80}$, $C_{20}@C_{80}@C_{180}$, $C_{20}@C_{80}@C_{180}C_{320}$) by performing molecular dynamics simulations. An empirical many-body potential function, Tersoff potential, for carbon is employed to calculate the interaction force among carbon atoms. Simulation results shows that carbon nanoonions are less resistive against heat treatment than single carbon nanoballs. Single carbon nanoballs such $C_{60}$ can resist heat treatment up to 5600 K, however, carbon nanoonions break down after 5100 K. This intriguing result offers insights into understanding the thermal-mechanical coupling phenomena of nanodevices and the complex process of fullerenes' formation.

Effects of Fiber Surface-Treatment and Sizing on the Dynamic Mechanical and Interfacial Properties of Carbon/Nylon 6 Composites

Cho, Dong-Hwan,Yun, Suk-Hyang,Kim, Jun-Kyung,Lim, Soon-Ho,Park, Min,Lee, Geon-Woong,Lee, Sang-Soo Korean Carbon Society 2004 Carbon Letters Vol.5 No.1

The effects of fiber surface-treatment and sizing on the dynamic mechanical properties of unidirectional and 2-directional carbon fiber/nylon 6 composites by means of dynamic mechanical analysis have been investigated in the present study. The interlaminar shear strengths of 2-directional carbon/nylon 6 composites sized with various thermosetting and thermoplastic resins are also measured using a short-beam shear test method. The result suggests that different surface-treatment levels onto carbon fibers may influence the storage modulus and tan ${\delta}$ behavior of carbon/nylon 6 composites, reflecting somewhat change of the stiffness and the interfacial adhesion of the composites. Dynamic mechanical analysis and short-beam shear test results indicate that appropriate use of a sizing material upon carbon fiber composite processing may contribute to enhancing the interfacial and/or interlaminar properties of woven carbon fabric/nylon 6 composites, depending on their resin characteristics and processing temperature.

MOLECULAR DYNAMICS SIMULATION OF POPC AND POPE LIPID MEMBRANE BILAYERS ENFORCED BY AN INTERCALATED SINGLE-WALL CARBON NANOTUBE

SERGEY SHITYAKOV,THOMAS DANDEKAR 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2011 NANO Vol.6 No.1

Using classical all-atom molecular dynamics simulation, we investigated the molecular dynamics of palmitoyloleoylphosphatidylcholine and palmitoyloleoylphosphatidylethanolamine membrane bilayers enforced by a single-wall carbon nanotube. We postulated that an insertion of a single-wall carbon nanotube in the center of lipid membrane "strengthens" ambient lipids and prevents the whole system from further destabilization by high temperatures. We implemented root mean square deviation and root mean square fluctuation analyses of simulated structures from their initial states in order to emphasize the molecular dynamics behavior of these structures during 1000 ps simulation time at different temperatures. The data suggest that an intercalated carbon nanotube restrains the conformational freedom of adjacent lipids and hence has an impact on the membrane stabilization dynamics. On the other hand, different lipid membranes may have dissimilarities due to the differing abilities to create a bridge formation between the adherent lipid molecules. The results derived from this work may be of importance in developing stable nanosystems for construction of novel biomaterials and delivery of various biomolecules in the fields of biosensors, biomaterials, and biophysics.

Natural and anthropogenic impacts on mangrove carbon dynamics: a systematic review protocol

Gilang Qur’ani Citra,이보라,Sasmito Sigit D.,Maulana Agus Muhamad,설미현,Wiradana Putu Angga,Leksono Budi,Watiniasih Ni Luh,Baral Himlal 한국산림과학회 2024 Forest Science And Technology Vol.20 No.1

The mangrove ecosystem serves as a vital habitat for coastal flora and fauna while playing a crucial role in storing and sequestering carbon as part of global carbon cycles. Therefore, it is imperative to evaluate the carbon dynamics, encompassing storage and sequestration, within mangrove ecosystems and their interconnectedness with natural climate fluctuations and anthropogenic influences, including land-use and land-cover changes (LULCC). Although there has been an increase in monitoring data and literature on mangrove carbon dynamics over the past two decades, there is still limited understanding regarding how climate variability, when combined with anthropogenic drivers, moderates the resilience of carbon storage and sequestration in mangroves. This study aims to build upon and enhance the previous systematic review conducted by Sasmito et al. (2019). Our specific objectives involve collating more recent literature published since 2018 and strengthening the analysis of carbon loss and recovery in tree biomass across different species, as well as its correlation with local and regional climate variations. Additionally, we will explore the impact of various types of land-use and land-cover changes on mangrove forests. Our systematic review will focus on field-based data collected from the Asia Pacific mangrove region, which represents the world’s largest and most diverse mangrove ecosystem and has been extensively studied in comparison to other regions, as indicated by previous systematic reviews. To gather relevant literature, we will conduct comprehensive searches across various databases, including Scopus, Web of Science, and Google Scholar. The structure established by Sasmito et al. (2019) for literature search, screening, and data extraction will be adopted. Data analysis will involve comparing carbon storage and sequestration under locally and regionally varying climatic conditions and anthropogenic influences. Furthermore, we will employ geographical mapping techniques to visualize species distribution and diversity with

Effects of Fiber Surface-Treatment and Sizing on the Dynamic Mechanical and Interfacial Properties of Carbon/Nylon 6 Composites

Dong-Hwan Cho,Suk-Hyang Yun,Jun-Kyung Kim,Soon-Ho Lim,Min Park,Geon-Woong Lee,Sang-Soo Lee 한국탄소학회 2004 Carbon Letters Vol.5 No.1

The effects of fiber surface-treatment and sizing on the dynamic mechanical properties of unidirectional and 2-directional carbon fiber/nylon 6 composites by means of dynamic mechanical analysis have been investigated in the present study. The interlaminar shear strengths of 2-directional carbon/nylon 6 composites sized with various thermosetting and thermoplastic resins are also measured using a short-beam shear test method. The result suggests that different surface-treatment levels onto carbon fibers may influence the storage modulus and tan δ behavior of carbon/nylon 6 composites, reflecting somewhat change of the stiffness and the interfacial adhesion of the composites. Dynamic mechanical analysis and short-beam shear test results indicate that appropriate use of a sizing material upon carbon fiber composite processing may contribute to enhancing the interfacial and/or interlaminar properties of woven carbon fabric/nylon 6 composites, depending on their resin characteristics and processing temperature.

탄소나노튜브 합성과정에 대한 원자수준 전산모사

김성엽(Sung Youb Kim),이영민(Youngmin Lee),임세영(Seyoung Im) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

Coalescence process of two carbon nanotubes is analyzed using action-derived molecular dynamics. The unit step of merging consists of only four sequential generalized Stone-Wales transformations which occur in four heptagon-hexagon pairs around jointed part. We show that additional single carbon atom may play a role of autocatalyst, which reduces the activation barrier of merging significantly. An atomistic pathway of the Tjunction formation of carbon nanotubes is presented and the energy barriers during the process are obtained as well. In this case, we employ the perfect nanotube-model with two additional carbon atoms. Our results confirm that the coalescence and junction formation of carbon nanotubes may happen more frequently than theoretical predictions at the moderate temperature in the presence of additional carbon atoms.

Computational fluid dynamics and tar formation in a low-temperature carbonization furnace for the production of carbon fibers

Pham, Hung Hai,Lim, Young-il,Ngo, Son Ich,Bang, Yun-Hyuk Elsevier 2019 Journal of industrial and engineering chemistry Vol.73 No.-

<P><B>Abstract</B></P> <P>A three-dimensional computational fluid dynamics (CFD) model with new permeability and off-gas emission equations was developed in a four-zone low-temperature furnace (LTF) for carbon fiber carbonization. Four performance criteria (residence time, dead-volume ratio, tow temperature standard deviation, and tar formation area) were proposed to identify the optimal ratio between the two N<SUB>2</SUB> flow rates introduced into the front and rear of LTF. A higher N<SUB>2</SUB> flow rate at the front rather than at the rear was preferred to reduce tar formation. The tar formation area calculated from carbon activity provides useful guideline for determining optimal LTF design and operating conditions.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Adsorption dynamics of methyl violet onto granulated mesoporous carbon: Facile synthesis and adsorption kinetics

Kim, Yohan,Bae, Jiyeol,Park, Hosik,Suh, Jeong-Kwon,You, Young-Woo,Choi, Heechul Elsevier 2016 Water research Vol.101 No.-

<P><B>Abstract</B></P> <P>A new and facile one-step synthesis method for preparing granulated mesoporous carbon (GMC) with three-dimensional spherical mesoporous symmetry is prepared to remove large molecular weight organic compounds in aqueous phase. GMC is synthesized in a single step using as-synthesized mesoporous carbon particles and organic binders through a simple and economical synthesis approach involving a simultaneous calcination and carbonization process. Characterization results obtained from SEM, XRD, as well as surface and porosity analysis indicate that the synthesized GMC has similar physical properties to those of the powdered mesoporous carbon and maintains the Brunauer-Emmett-Teller (BET) surface area and pore volume because the new synthesis method prevents the collapse of the pores during the granulation process. Batch adsorption experiments revealed GMC showed a substantial adsorption capacity (202.8 mg/g) for the removal of methyl violet as a target large molecular contaminant in aqueous phase. The mechanisms and dynamics modeling of GMC adsorption were also fully examined, which revealed that surface diffusion was rate limiting step on adsorption process of GMC. Adsorption kinetics of GMC enables 3 times faster than that of granular activated carbon in terms of surface diffusion coefficient. This is the first study, to the best of our knowledge, to synthesize GMC as an adsorbent for water purification by using facile granulation method and to investigate the adsorption kinetics and characteristics of GMC. This study introduces a new and simple method for the synthesis of GMC and reveals its adsorption characteristics for large molecular compounds in a water treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Granular mesoporous carbon (GMC) is synthesized by using the facile one-step synthesis method. </LI> <LI> GMC showed a substantial adsorption capacity for the removal of methyl violet in aqueous phase. </LI> <LI> Adsorption kinetics of GMC is 3 times faster than that of GAC in terms of surface diffusion coefficient. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Hydrodynamics of low temperature carbonization furnace for production of polyacrilonitrile (PAN)-based carbon fiber

Pham, Hung H.,Lim, Young-il,Cho, Cheol-Ho,Bang, Yun-Hyuk Elsevier 2017 Chemical engineering research & design Vol.128 No.-

<P><B>Abstract</B></P> <P>An incompressible gas phase three dimensional (3D) computational fluid dynamics (CFD) model with turbulence and radiation was developed to investigate hydrodynamics of a low temperature furnace (LTF) for polyacrylonitrile (PAN)-based fiber carbonization. Thirty PAN-fiber tows moving at a constant linear speed emitted off-gas and their porosity increased during carbonization. The CFD model included off-gas mass flow rates of eight species with respect to temperature, which were treated as a source term from the tows. Velocity, temperature, and concentration profiles along the furnace length were examined according to three duct positions (e.g., front, middle and rear sides of LTF). The off-gas residence time, dead-zone (or stagnant gas region) ratio, and temperature uniformity were used as performance criteria of LTF. An optimal duct position was determined on the front side of LTF considering the three performance criteria.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CFD model with radiation for low temperature carbonization furnace (LTF) of PAN-fiber. </LI> <LI> CFD model coupled with off-gas emission rate as a function of temperature. </LI> <LI> Residence time, dead zone ratio, and temperature uniformity as performance criteria. </LI> <LI> Optimal duct position considering the three performance criteria was the front of LTF. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

폐활성탄을 혼입한 콘크리트의 물리.역학적 성질

강현수,성찬용,Kang, Hyun-Soo,Sung, Chan-Yong 한국농공학회 2009 한국농공학회논문집 Vol.51 No.1

This study was performed to evaluate the physical and mechanical properties of concrete using waste activated carbon. Materials used were ordinary portlant cement, crushed coarse aggregate, natural fine aggregate, waste activated carbon, and superplasticizer. The substitution ratios of waste activated carbon were 0,1,2,3,4,5,6,7,8,9 and 10%. The unit weight was decreased and water absorption ratio was increased with increasing the waste activated carbon content, respectively. When the substitution ratio of waste activated carbon was 3%, compressive strength, flexural strength and dynamic modulus of elastisity were more higher than that of the ordinary portland cement (OPC), and it was decreased with increasing the waste activated carbon content, respectively. The most effective contents of waste activated carbon was 2% in performance and 4% in practical use Accordingly, waste activated carbon can be used for concrete material.