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SYNTHESIS AND CHARACTERIZATION OF A FLAME RETARDANT HYPERBRANCHED POLYETHER

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Chinese Journal of Polymer Science 2010年第1期28卷 107-118页

作者： Jyotishmoy Borah 汪传生 niranjan Karak College of Electromechanical Engineering Qingdao University of Science and Technology Department of Chemical Sciences Tezpur UniversityNapaamIndia-784028

A brominated hyperbranched polyether has been synthesized from cyanuric chloride and sodium salt of tetrabromobisphenol-A by an A2 ＋ B3 approach. The synthesized polyether was characterized by ^1H-NMR, ^13C-NMR, UV, FTIR spectroscopy and X-ray diffraction studies, measurements of solution viscosity, molecular weight and solubility and elemental and thermogravimetric analyses. The flame retardancy of the synthesized polyether and its blends with commercially available plasticized poly（vinyl chloride）（PVC） and low density polyethylene （LDPE） was investigated by measurements of limiting oxygen index （LOI） value and thermogravimetric analysis. The properties are compared with a non-halogenated similar type of bisphenol-A based aromatic polyether after blending at different dose levels with the same base polymers. The LOI values of these blends indicated that these hyperbranched polyethers acted as flame retardant additives, and antimony trioxide had prominent synergistic effect with the bromo hyperbranched polyether for the above base polymers, and an increment of 4 to 6 units in LOI values was observed.

关键词： Hyperbranched polyether LOI LDPE PVC.

In-plane and out-of-plane quasi-static compression performance enhancement of 3D printed re-entrant diamond auxetic metamaterial with geometrical tuning and fiber reinforcement

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Defence Technology（防务技术） 2023年第7期25卷 1-17页

作者： niranjan Chikkanna Shankar Krishnapillai Velmurugan Ramachandran Department of Mechanical Engineering Indian Institute of Technology Madras600036India Department of Aerospace Engineering Indian Institute of Technology Madras600036India

Auxetic materials are cellular materials with a unique property of negative Poisson’s *** auxeticity and performance of these metamaterials utterly depend on the geometrical parameters and loading *** the first time,the quasi-static uniaxial compression performance of fused filament fabricated re-entrant diamond auxetic metamaterial is evaluated in the x-direction(in-plane)and z-direction(out-of-plane).The most commonly used thermoplastic feedstock,Acrylonitrile butadiene styrene,is considered a material of *** effect of influential geometrical parameters of the re-entrant diamond structure and printing parameter is systematically studied using Taguchi’s design of ***-based multi-objective optimisation technique has been adopted to arrive at the optimal *** are made to improve the stiffness and strength of the structure with fibre *** glass fibre reinforcements have enhanced specific strength and stiffness in both in-plane and out-ofplane directions.A sevenfold and thirteen times increase in specific strength and energy absorption is evident for glass fibre-reinforced structures in out-of-plane directions compared to in-plane *** tuning of geometrical parameters of the re-entrant diamond structure can result in a Poisson’s ratio of up to-3.49 when tested in the *** parametric study has illustrated the tailorability of the structure according to the application *** statistical study has signified each considered parameter’s contribution to the compression performance characteristics of the 3D printed re-entrant diamond auxetic metamaterial.

关键词： Auxeticity Fibre reinforcement Tailorability Anisotropy Geometrical influence Property enhancement

Solar-Driven Hydrogen Peroxide Production Using Polymer-Supported Carbon Dots as Heterogeneous Catalyst

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Nano-Micro Letters 2017年第4期9卷 30-40页

作者： Satyabrat Gogoi niranjan Karak Advanced Polymer and Nanomaterial Laboratory Department of Chemical SciencesTezpur UniversityTezpur 784028AssamIndia

Safe, sustainable, and green production of hydro gen peroxide is an exciting proposition due to the role of hydrogen peroxide as a green oxidant and energy carrier for fuel cells. The current work reports the development of carbon dot-impregnated waterborne hyperbranched polyurethane as a heterogeneous photo-catalyst for solar-driven production of hydrogen peroxide. The results reveal that the carbon dots possess a suitable band-gap of 2.98 eV,which facilitates effective splitting of both water and ethanol under solar irradiation. Inclusion of the carbon dots within the eco-friendly polymeric material ensures their catalytic activity and also provides a facile route for easy catalyst separation, especially from a solubilizing *** overall process was performed in accordance with the principles of green chemistry using bio-based precursorsand aqueous medium. This work highlights the potential of carbon dots as an effective photo-catalyst.

关键词： Carbon dot Photo-catalyst Heterogeneous catalyst Hydrogen peroxide

Removal of Dye Using Lignin-Based Biochar/Poly(ester amide urethane)Nanocomposites from Contaminated Wastewater

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Journal of Renewable Materials 2024年第9期12卷 1507-1540页

作者： Annesha Kar niranjan Karak Advanced Polymer and Nanomaterial Laboratory(APNL) Department of Chemical SciencesTezpur UniversityNapaamTezpur784028India Research and Development RymbalRTCSahibabad Industrial Area Site 4SahibabadGhaziabad201010India

The pursuit of incorporating eco-friendly reinforcing agents in polymer composites has accentuated the exploration of various natural biomass-derived *** burgeoning environmental crisis spurred by the discharge of synthetic dyes into wastewater has catalyzed the search for effective and sustainable treatment *** the various sorbent materials explored,biochar,being renewable,has gained prominence due to its excellent adsorption properties and environmental *** has also emerged as a focal point for its potential to replace other conventional reinforcing agents,viz.,fumed silica,aluminum oxide,treated clays,*** study introduces a novel class of polymer nanocomposites comprising of lignin-based biochar particles and poly(ester amide urethane)matrix via a feasible *** structural evaluation of these nanocomposites was accomplished using Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,and powder X-ray *** polymer nanocomposites exhibited superior mechanical properties with an increment in tensile strength factor by 45%in comparison to its pristine matrix,along with an excellent toughness value of 90.22 MJm^(−3)at a low loading amount of only 1 wt%.The composites showed excellent improvement in thermal properties with a sharp rise in the glass transition temperature(Tg)value from−28.15℃to 84℃,while also championing sustainability through inherent biodegradability *** their structural prowess,these polymer nanocomposites demonstrated excellent potential as adsorbents,displaying efficient removal of malachite green and tartrazine dyes from aqueous systems with a removal efficiency of 87.25%and 73.98%,*** kinetics study revealed the pseudo second order model to be the precision tool to assess the dye removal *** this,the Langmuir adsorption isotherm provided a framework to assess the sorption features of the polymer ***,these ren

关键词： Reinforcing agents biochar polymer nanocomposites poly(ester amide urethane) dye removal adsorption kinetics pseudo second order model langmuir isotherm

Evaluation of regression algorithms for estimating leaf area index and canopy water content from water stressed rice canopy reflectance

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Information Processing in Agriculture 2021年第2期8卷 284-298页

作者： niranjan Panigrahi Bhabani Sankar Das Agricultural and Food Engineering Department Indian Institute of Technology KharagpurWest Bengal 721302India School of Water Energy and EnvironmentCranfield UniversityCranfield MK430ALUK

Optical remote sensing(RS)with robust algorithms is needed for accurate assessment of crop canopy *** intensive studies on algorithms,their performance using RS needs to be *** evaluated five different algorithms(partial-least-squares regression(PLSR),support vector regression(SVR),random forest regression(RFR),locally-weighted-PLSR(PLSRLW)and PLSR with feature selection(PLSRFS))for rapid assessment of leaf area index(LAI)and canopy water content(CWC)for rice canopies using canopy reflectance spectra over visible to short-wave infrared *** pooled datasets of LAI(600)and CWC(480)were collected from two replicated field experiments during 2014–15 and 2015–16 rice growing *** performance of each algorithm was evaluated using coefficient of determination(R^(2)).Results showed that PLSRLW performed more accurately than other algorithms with R^(2) values 0.77 and 0.66 for LAI and CWC,*** also used a bootstrapping approach to generate a kernel density estimator of root mean squared error values for each *** results suggested that the improvement in prediction accuracy of LAI and CWC can be achieved if a suitable algorithm is selected by assigning higher weights to calibration samples,which has similar canopy structure as the test *** of the canopy spectral data results large error values in test dataset,therefore the use of entire season canopy spectral data should be used for model calibration.

关键词： Rice canopy Reflectance spectroscopy Calibration Retrieval algorithms Partial-least-squares regression

Transmission congestion management considering multiple and optimal capacity DGs

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Journal of Modern Power Systems and Clean Energy 2017年第5期5卷 713-724页

作者： Rajagopal PEESAPATI Vinod Kumar YADAV niranjan KUMAR Department of Electrical Engineering National Institute of Technology JamshedpurJamshedpurJharkhand 831014India Department of Electrical Engineering Gautam Buddha UniversityNoida 201334India

Transmission congestion management became a grievous issue with the increase of competitiveness in the power systems. Competitiveness arises due to restructuring of the utilities along with the penetration of auxiliary services. The present study depicts a multi objective technique for achieving the optimal capacities of distributed generators(DG) such as solar, wind and biomass in order to relieve congestion in the transmission lines. Objectives like transmission congestion, real power loss, voltages and investment costs are considered to improve the technical and economical performances of the network. Multi objective particle swarm optimization algorithm is utilized to achieve the optimal sizes of unity power factor DG *** insisted methodology is practiced on IEEE-30 and IEEE-118 bus systems to check the practical *** results of the proposed approach are compared with the genetic algorithm for both single and multi-objective cases. Results revealed that the intimated method can aid independent system operator to remove the burden from lines in the contingency conditions in an optimal manner along with the improvement in voltages and a reduction in real power losses of the network.

关键词： Transmission congestion Optimal power flow Distributed generation Particle swarm optimization

Performance comparison of mono and polycrystalline silicon solar photovoltaic modules under tropical wet and dry climatic conditions in east-central India

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Clean Energy 2022年第1期6卷 165-177页

作者： niranjan Singh Baghel Nikhil Chander Department of Electrical Engineering and Computer Science Indian Institute of Technology BhilaiGEC CampusSejbaharRaipur-492015ChhattisgarhIndia

This work focuses on the performance comparison of monocrystalline and polycrystalline Si solar photovoltaic(SPV)modules under tropical wet and dry climatic conditions in east-central India(21.16°N 81.65°E,Raipur,Chhattisgarh).This study would help to select the SPV module for system installation in the east-central part of the *** comparative analysis,we used performance ratio(PR)and efficiency as figures of *** plane-of-array(POA)irradiance was used to determine the efficiency of the *** decomposition and transposition models calculated the POA values from the measured global horizontal *** data were analysed systematically for 6 months in the non-rainy season,from October 2020 to March *** attention was given to solar irradiance,ambient temperature and module temperature-the parameters that affect the performance of PV *** month of October showed the highest variation in irradiance and *** highest average module temperatures(51-52℃)were observed in October-November,while the lowest average module temperatures(34℃ for mono-Si and 36℃ for poly-Si)were observed in *** highest value of average monthly POA irradiance(568 W/m^(2))was observed in February and the lowest(483 W/m^(2))in *** results showed that the monocrystalline SPV module performed better than the polycrystalline module under all weather *** maximum observed values of mono-Si and poly-Si panel PRs were 0.89 and 0.86,respectively,in December.

关键词： solar photovoltaic performance climatic conditions global horizontal irradiance plane-of-array

Effect of process parameters on depth of penetration and topography of AZ91 magnesium alloy in abrasive water jet cutting

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Journal of Magnesium and Alloys 2018年第4期6卷 366-374页

作者： C A niranjan S Srinivas M Ramachandra Department of Mechanical Engineering BMS College of EngineeringBengaluru-India

In the present study,the influence of dynamic process parameters such as water pressure,traverse speed and abrasive mass flow rate on depth of penetration and surface topography in high strength AZ91 magnesium alloy were investigated using Abrasive Water Jet(AWJ)cutting *** parameters were varied at 3 levels and influences of each parameter on penetration ability were identified using analysis of variance(ANOVA).Contribution of water pressure and traverse speed on jet penetration found higher compared to abrasive mass flow *** projector was used to measure depth of *** features and topography of cut surfaces were examined using Scanning Electron Microscopy(SEM).Micro cutting and ploughing were observed on the top and bottom portion of the cut which were similar to that of modes of deformation in other ductile materials like aluminium and *** roughness of cut surfaces was measured using Taylor Hobson surface roughness *** roughness found higher at higher traverse speeds and lower at lower traverse *** study also highlights the suitability of AWJ cutting technology for cutting magnesium and its alloys.

关键词： AZ91 magnesium alloy Depth of penetration Profile projector Topography

Maxwell's equal area law for Vaidya-Bonner-de Sitter black hole under Lorentz invariance violation

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Chinese Physics C 2024年第11期48卷 231-246页

作者： Yenshembam Priyobarta Singh Telem Ibungochouba Singh Sapam niranjan Singh Department of Mathematics Manipur UniversityCanchipurImphal 795003ManipurIndia

In this study,we investigate the tunneling of fermions with arbitrary spin near the event horizon of a nonstationary Vaidya-Bonner-de Sitter(VBdS)black hole under Lorentz invariance violation(LIV).The modified Hawking temperature of VBdS black holes is calculated by using tortoise coordinate transformation,Feynman prescription,and Wentzel-Kramers-Brillouin *** considering the cosmological constant as a thermodynamic pressure in the extended phase space,we construct a Maxwell's equal area law under LIV and study the phase transitions of VBdS black hole in P-v,P-V,and T-S *** LIV increases the length of the liquid-gas coexistence *** thermodynamic quantities such as the entropy,heat capacity,Helmholtz free energy,internal energy,enthalpy,and Gibbs free energy of the VBdS black hole are *** quantities tend to increase under *** stability of the black hole is also discussed in the presence of LIV.

关键词： Hawking temperature Lorentz invariance violation Maxwell's equal area law Entropy