Kinetics of Thermal Degradation of Polypropylene/Nanoclay/Wood Flour Nanocomposites

Mohan D. Jagan,Lee SunYoung,Kang InAeh,Doh GeumHyun,Park ByungDae,Wu Qinglin 한국유화학회 2007 한국응용과학기술학회지 Vol.24 No.3

As a part of enhancing the performance of wood-plastic composites (WPC), polypropylene (PP)/ nanoclay (NC)/ wood flour (WF) nanocomposites were prepared using melt blending and injection molding process to evaluate their thermal stability. Thermogravimetric analysis (TGA) was employed to investigate thermal degradation kinetics of the nanocomposites both dynamic and isothermal conditions. Dynamic scans of the TGA showed an increased thermal stability of the nanocomposites at moderate wood flour concentrations (up to 20 phr, percentage based on hundred percent resin) while it decreased with the addition of 30 phr wood flour. The activation energy (Ea) of thermal degradation of nanocomposites increased when nanoclay was added and the concentration of wood flour increased. Different equations were used to evaluate isothermal degradation kinetics using the rate of thermal degradation of the composites, expressed as weight loss (%) from their isothermal TGA curves. Degradation occurred at faster rate in the initial stages of about 60 min., and then proceeded in a gradual manner. However, nanocomposites with wood flour of 30 phr heated at 300^circC showed a drastic difference in their degradation behavior, and reached almost a complete decomposition after 40 min. of the isothermal heating. The degree of decomposition was greater at higher temperatures, and the residual weight of isothermal degradation of nanocomposites greatly varied from about 10 to 90%, depending on isothermal temperatures. The isothermal degradation of nanocomposites also increased their thermal stability with the addition of 1 phr nanoclay and of wood flour up to 20 phr. But, the degradation of PP100/NC1/MAPP3/WF30 nanocomposites with 30 phr wood flour occurs at a faster rate compared to those of the others, indicating a decrease in their thermal stability.

Kinetics of Thermal Degradation of Polypropylene/Nanoclay/Wood Flour Nanocomposites

( D. Jagan Mohan ),( Sun Young Lee ),( In Aeh Kang ),( Geum Hyun Doh ),( Byung Dae Park ),( Qing Lin Wu ) 한국유화학회 2007 한국응용과학기술학회지 Vol.24 No.3

High performance photodiodes based on chemically processed Cu doped SnS₂ nanoflakes

Mohan Kumar, G.,Xiao, Fu,Ilanchezhiyan, P.,Yuldashev, Sh.,Madhan Kumar, A.,Cho, H.D.,Lee, D.J.,Kang, T.W. Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.455 No.-

<P><B>Abstract</B></P> <P>In this work, Cu doped SnS<SUB>2</SUB> nanoflakes were synthesized through a simple hydrothermal method. The influence of Cu doping on the structural, optical and electrical properties of SnS<SUB>2</SUB> were investigated in detail. Optical properties explores the Cu doping in SnS<SUB>2</SUB> crystal lattice to result with a red-shift in absorption spectrum, which benefits visible-light absorption. Photodiodes were further fabricated by spin coating Cu doped SnS<SUB>2</SUB> nanoflakes on p-type silicon (Si). Electrical and photoelectrical parameters of Cu doped SnS<SUB>2</SUB> nanoflakes were determined by studying their impedance and current–voltage (I–V) characteristics, respectively. The diodes were found to exhibit excellent rectifying behavior and good sensitivity on par to pristine photodiodes. Impedance results identified the resistance of device to reduce considerably on Cu doping. The enhanced photoelectrical properties of the heterojunctions has been ascribed to Cu ions, which act as effective dopant and contribute to the varied carrier concentration in SnS<SUB>2</SUB>. Finally the obtained results suggest the potential of Cu-doped SnS<SUB>2</SUB> for application in photodetection and sensors applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu doped SnS<SUB>2</SUB> nanoflakes were synthesized in hexagonal phase. </LI> <LI> Nature of charge carriers/carrier density was determined using Mott-Schottky plots. </LI> <LI> Photodiode based on Cu doped SnS<SUB>2</SUB> nanoflakes were fabricated on p-Si substrate. </LI> <LI> Photodiode revealed improved photocurrent and responsitivity values under illumination. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Analyze the various effects of cutting tools in the machining of titanium alloy

D. Ananda Kumar,A. Murugarajan,E. Mohan 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.3

Titanium alloy has dominated in mechanical-based industries due to its superior tensile strength, toughness, and corrosionresistance. This research involves the development of a wear model integrated with the FEM model. A numerical study andexperimental work were conducted to variant tool nose radius, cutting speed, and feed rate in the machining of titanium alloy. The machining operation was properly simulated using Deform2D commercial-based software to predict the cutting force, toolwear, and cutting zone temperature. In addition, the same output response was assessed in the experimental technique byemploying all geared lathes. In both the experiment and simulation conditions, the least cutting force was produced at thelowest feed rate and the smallest nose radius. It was noticed from the data that the cutting zone temperature at the cuttingzone region was raised with an increase in the tool nose radius. Utmost tool wear was recorded at the minimal tool nose radiusand minimum feed rate. Cutting speed plays a vital function in the evaluation of tool wear and nose radius in the predictionand assessment of cutting tool force and tool interface temperature. Tool wear study and surface morphology were fullyexplored with the assistance of SEM images.

Analysis. Design and Control of Two-Level Voltage Source Converters for HVDC Systems

Mohan, D. Madhan,Singh, Bhim,Panigrahi, B.K. The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.3

The Voltage Source Converter (VSC) is replacing the conventional line commutated current source converters in High Voltage DC (HVDC) transmission systems. The control of a two-level voltage source converter and its design dealt with HVDC systems and various factors such as reactive power, power factor, and harmonics distortion are discussed in detail. Simulation results are given for the two-level converter and designed control is used for bidirectional power flow. The harmonics minimization is taken by extending the 6-pulse VSC to multipulse voltage source converters. The control is also tested and simulated for a 12-pulse voltage source converter to minimize the harmonic distortion in AC currents.

Analysis, Design and Control of Two-Level Voltage Source Converters for HVDC Systems

D. Madhan Mohan,Bhim Singh,B. K. Panigrahi 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.3

The Voltage Source Converter (VSC) is replacing the conventional line commutated current source converters in High Voltage DC (HVDC) transmission systems. The control of a two-level voltage source converter and its design dealt with HVDC systems and various factors such as reactive power, power factor, and harmonics distortion are discussed in detail. Simulation results are given for the two-level converter and designed control is used for bidirectional power flow. The harmonics minimization is taken by extending the 6-pulse VSC to multipulse voltage source converters. The control is also tested and simulated for a 12-pulse voltage source converter to minimize the harmonic distortion in AC currents.

Poly(N-isopropylacrylamide-co-sodium acrylate) hydrogels: Interactions with surfactants

Mohan, Y. M.,Joseph, D. K.,Geckeler, K. E. Wiley Subscription Services, Inc., A Wiley Company 2007 Journal of applied polymer science Vol.103 No.5

<P>Poly(N-isopropylacrylamide-co-sodium acrylate) [poly(NIPAM-co-SA)] hydrogels were modified with three different kind of surfactants (cationic, anionic, and nonionic) to study the effect on the swelling properties. The structural variation of the surfactant-modified hydrogels was investigated in detail. The interaction between the surfactants and the hydrogel varies and strictly depends on the surfactant type. The variation in thermal stability of the modified surfactant hydrogels was investigated and compared with unmodified hydrogel. Further, the hydrogel swelling/diffusion kinetic parameters were investigated and diffusion of water into hydrogel was found to be of the non-Fickian transport mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3423–3430, 2007</P>

Evidencing enhanced charge-transfer with superior photocatalytic degradation and photoelectrochemical water splitting in Mg modified few-layered SnS₂

Mohan Kumar, G.,Cho, H.D.,Ilanchezhiyan, P.,Siva, C.,Ganesh, V.,Yuldashev, Sh.,Madhan Kumar, A.,Kang, T.W. Elsevier 2019 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.540 No.-

<P><B>Abstract</B></P> <P>Recently there has been immense interest in the exploration of richly available two-dimensional non-toxic layered material such as tin disulfide (SnS<SUB>2</SUB>) for potential employment in energy and environmental needs. In this regard, we report on the synthesis of few-layered Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB> nanosheets through a facile one-step hydrothermal route to address all such functions concerning photocatalysis and photoelectrochemical conversion. The crystalline order and structure of processed layered Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB> were initially found to exhibit a strong influence on their physicochemical properties. Their optical properties attest the Mg doping in SnS<SUB>2</SUB> to benefit us with enhanced visible-light absorption via red-shift in their absorption edge. In the photoluminescence spectrum the emissions observed along visible and red region signifies the association of Mg related trap states in Sn<SUB>1−x</SUB>Mg<SUB>x</SUB>S<SUB>2</SUB>. Next, the photocurrent and electrochemical impedance spectroscopic results revealed the Mg doping to promote the effective charge transfer process (which was beneficial to enhance their photocatalytic activity). Consequently, the layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> made photoanodes displayed 1.7 fold higher photocurrent density under simulated solar radiation with respect to their undoped counterpart. Furthermore, the layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets exhibits enhanced visible light decomposition of organic dye while compared with pristine SnS<SUB>2</SUB> nanosheets. The value of rate constants obtained for the Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets was found to be 1.4 times higher than that of pristine SnS<SUB>2</SUB>. Finally, the results obtained through the present study projects the huge potential of layered Sn<SUB>0.98</SUB>Mg<SUB>0.02</SUB>S<SUB>2</SUB> nanosheets for future multifunctional applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Preoperative Neck Disability Severity Limits Extent of Postoperative Improvement Following Cervical Spine Procedures

Elliot D.K. Cha,Conor P. Lynch,Shruthi Mohan,Cara E. Geoghegan,Caroline N. Jadczak,Kern Singh 대한척추신경외과학회 2021 Neurospine Vol.18 No.2

Objective: Our study aims to evaluate the impact of severity of preoperative Neck Disability Index (NDI) on postoperative patient-reported outcome measures (PROMs). Methods: A retrospective review of primary, elective, single or multilevel anterior cervical discectomy and fusion or cervical disc arthroplasty procedures between 2013 and 2019 was performed. Visual analogue scale (VAS) neck and arm, NDI, 12-item Short Form physical and mental composite score (SF-12 PCS and MCS), Patient-Reported Outcome Measurement Information System physical function, and 9-item Patient Health Questionnaire (PHQ-9) were collected preoperatively and postoperatively. Patients were categorized by preoperative NDI: none-to-mild disability (<30); moderate disability (≥30 to <50); severe disability (≥50 to <70); complete disability (≥70). The impact of preoperative NDI on PROM scores and minimum clinically important difference (MCID) achievement rates were evaluated. Results: The cohort included 74 patients with none-to-mild disability, 95 moderate, 76 severe, and 17 with complete disability. Patients with greater preoperative disability demonstrated significantly different scores for NDI, VAS neck, SF-12 MCS, and PHQ-9 at all timepoints (p<0.001). Patients with more severe disability demonstrated different magnitudes of improvement for NDI (all p<0.001), VAS neck (p≤0.009), VAS arm (p=0.025), and PHQ-9 (p≤0.011). The effect of preoperative severity on MCID achievement was demonstrated for NDI and for PHQ-9 (p≤0.007). Conclusion: Patients with severe neck disability demonstrated differences in pain, disability, physical and mental health. MCID achievement also differed by preoperative symptoms severity. Patients with more severe neck disability may be limited to the degree of improvement in quality of life but perceive them as significant changes.

나노입자 적층시스템을 이용한 그라파이트 적층 및 응용

천두만(D. M. Chun),Mohammad Nur E Alam Al Nasim,Mohaned Mohammed Mahmoud Moham,홍성태(S. T. Hong) Korean Society for Precision Engineering 2018 한국정밀공학회 학술발표대회 논문집 Vol.2018 No.10월