Electrical, mechanical, and energy harvesting of a pyroelectric polymer nanocomposite

Panwar Lokesh Singh,Panwar Varij,Ansari Mohd Umer,Anoop Gopinathan,Park Sukho 한국물리학회 2023 Current Applied Physics Vol.52 No.-

Flexible pyroelectric devices can convert waste heat from the human body, sun, industry, geothermal, and automobiles into renewable electricity. In this paper, carbon nanofiber (CNF) and poly(2-acrylamide-2-methyl-1- propane-sulfonic acid) and PAMPS attached poly(vinylidene fluoride) (PVDF) pyroelectric polymer nanocomposite (PyPNC) were investigated for electrical, mechanical, and pyroelectric performance with temperature variations. The ac conductivity and open circuit voltage of PyPNC increased with temperature. The PyPNC showed the enhanced AC conductivity (σac) of 89 S/cm and open circuit output voltage of 4.8 V at 120 ◦C due to the alignment of CNF with PAMPS beads that enhanced the volume fraction of the β-phase in PyPNC at 120 ◦C than that of the random orientation of CNF with PAMPS beads of PyPNC at 20 ◦C, 50 ◦C, and 150 ◦C.

Studies on Some Bioactive 1,1-Bis(2-benzylidene-5-aryliden-1,3-thiadiazolidin-4-one)cyclopropane

Panwar, Hemant,Chaudhary, Nidhi,Singh, Sachi,Chawla, Amit Korean Chemical Society 2011 대한화학회지 Vol.55 No.6

Some novel heterocyclic derivatives of 1,1-bis(2-phenyl-5-arylidine-1,3-thiadiazolidin-4-one)cyclopropane 4(a-i) have been synthesized from cyclopropane dicarboxylic acid and substituted thiadiazole moieties. All the synthesized compounds have been characterized by elemental and spectral (I.R., $^1H$-NMR, Mass) analysis. Furthermore, above said compounds were screened for their antifungal and antibacterial activities. Compound 4c was found the most potent one which further evaluated for lesser toxicity test.

Kinetic Alfven solitary waves in a magnetized plasma with superthermal electrons

Panwar, A.,Ryu, C. M.,Bains, A. S. American Institute of Physics 2015 Physics of plasmas Vol.22 No.9

Low voltage actuator using ionic polymer metal nanocomposites based on a miscible polymer blend

Panwar, V.,Jeon, J. H.,Anoop, G.,Lee, H.,Oh, I. K.,Jo, J. Royal Society of Chemistry 2015 Journal of Materials Chemistry A Vol.3 No.39

Electrical, dielectric, and electromagnetic shielding properties of polypropylene-graphite composites

Panwar, Varij,Park, Jong-Oh,Park, Suk-Ho,Kumar, Sanjeev,Mehra, R. M. Wiley Subscription Services, Inc., A Wiley Company 2010 Journal of applied polymer science Vol.115 No.3

<P>The conducting polymer composite material is desired to have a high dielectric constant and high dissipation factor in low and high frequency ranges, so that it can be used in charge storing devices, decoupling capacitors, and electromagnetic interference (EMI) shielding applications. Currently, on-going research is trying to enhance the dielectric constant of ceramic powder-polymer, metal powder-polymer, and nanotube-polymer composites in the low frequency region. In this article, we present the dielectric properties of polypropylene (PP)-graphite (Gr) composites in low and radio frequency ranges. Furthermore, the EMI shielding properties of these composites are examined in the radio frequency range. The PP-Gr composites were prepared by mixing and the hot compression mold technique. The electrical conductivity and dielectric constant of PP-Gr composites with graphite volume fraction follow the power law model of percolation theory. The percolation threshold of the composites is estimated to be 0.0257 (∼ 5wt % of Gr). The current of PP-Gr composites as a function of voltage shows a nearly ohmic behavior above the percolation threshold. Shore-D hardness of the composites is decreased with the addition of conducting filler. The PP-Gr composites exhibit a high dielectric constant and high dissipation factor with the addition of graphite in low frequency and radio frequency regions, so they can be used in the proposed applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010</P>

Novel optimization method of single square FSS impinged and cascaded radar absorbing composites

Panwar, Ravi,Son, Dae-Sung,Lee, Jung-Ryul VSP 2018 Advanced Composite Materials Vol. No.

<P>It is well known that radar absorbing potentiality of existing magneto-dielectric composites can be significantly enhanced by the application of frequency selective surface (FSS) and cascaded electromagnetic (EM) structures. But the optimization of such complex EM structures and validation of the adopted optimization strategy is still a very challenging task for the researchers. Therefore, in this study, an effective effort has been made for the optimization and the corresponding validation for Single Square FSS (SS-FSS) impinged and cascaded radar wave absorbers using advanced computational EM software's like FEldberechnung furKorper mit beliebigerOberflache - a German acronym (FEKO) and high frequency structure simulator (HFSS). In addition, a critical analysis of dielectric constant (epsilon) has been carried out to select the best combination of composites for the development of efficient radar wave absorbers. A comparison between optimized and simulated results have been carried out to examine the effect of advanced EM approaches over reflection loss (RL) characteristics of composite radar absorbing materials (CRAMs). A rapid change in radar absorption properties of composites has been observed after the application of SSFSS and cascading. A SS-FSS impinged composite has been found to provide a wide absorption bandwidth of 3.6GHz at X-band. A cascaded absorber having layer thickness 1.8mm provides a peak RL of -42.6dB at 10.6GHz with an absorption bandwidth of 2.5GHz. The strong agreement between mathematical model, HFSS and FEKO results clearly reflects the efficiency of adopted approach for distinct practical EM applications.</P>

Fabrication of conducting composite sheets using cost-effective graphite flakes and amorphous styrene acrylonitrile for enhanced thermistor, dielectric, and electromagnetic interference shielding properties

Panwar, Varij,Gill, Fateh Singh,Rathi, Vikas,Tewari, V.K.,Mehra, R.M.,Park, Jong-Oh,Park, Sukho Elsevier 2017 Materials chemistry and physics Vol.193 No.-

<P><B>Abstract</B></P> <P>The fabrication of strong conducting composite sheets (CCSs) using a simple technique with cost-effective materials is desirable for capacitor, decoupling capacitor, and electromagnetic interference (EMI) shielding applications. Here, we used cost-effective graphite flakes (GFs) as a conducting filler and amorphous poly (styrene-co-acrylonitrile) (PSAN) as an insulating polymer to fabricate a CCS via a simple mechanical mixing and hot compression molding process in 2.5 h, with the aim to save time and avoid the use of toxic reagents, which are generally used in chemical methods. In the present method, the GFs are connected in diffusively adhere polymer matrix, controlled by temperature and pressure that generate the conduction in the CCSs. The resulting PSAN/GF CCSs were characterized by using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and hardness tests. The GFs penetrated the interfacial region of PSAN, thus improving the thermistor and dielectric properties (dielectric constant, AC conductivity, and dissipation factor) of the PSAN/GF CCSs. Furthermore, the PSAN/GF CCSs showed enhanced hardness and EMI shielding effectiveness (SE) properties in the X-band frequency range (8.5–12.5 GHz). The percolation theory was implemented to DC and AC conductivity. To detect the transition of the dielectric properties, the dielectric constant of the CCSs was analyzed with increasing volume fraction of GFs in the radio frequency region. The improved dielectric constant, AC conductivity, and dissipation factor of the PSAN/GF CCS, indicated a significant improvement in their EMI shielding properties in the X-band frequency range, which were measured using the waveguide method. The ac conductivity of PSAN/GF CCS shows stable behavior in the higher frequency ranges. The EMISE of PSAN/GF CCS were found to increase with increasing GF content due to the absorbance mechanism.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Enhanced hardness and thermal stability of PSAN/GF conducting composite sheet (CCS). </LI> <LI> Enhanced dielectric and electromagnetic interference shielding of PSAN/GF CCS. </LI> <LI> Cost-effective and fast fabrication method of PSAN/GF CCS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Performance and non-destructive evaluation methods of airborne radome and stealth structures

Panwar, Ravi,Lee, Jung Ryul IOP Pub 2018 Measurement science & technology Vol.29 No.6

<P>In the past few years, great effort has been devoted to the fabrication of highly efficient, broadband radome and stealth (R&S) structures for distinct control, guidance, surveillance and communication applications for airborne platforms. The evaluation of non-planar aircraft R&S structures in terms of their electromagnetic performance and structural damage is still a very challenging task. In this article, distinct measurement techniques are discussed for the electromagnetic performance and non-destructive evaluation (NDE) of R&S structures. This paper deals with an overview of the transmission line method and free space measurement based microwave measurement techniques for the electromagnetic performance evaluation of R&S structures. In addition, various conventional as well as advanced methods, such as millimetre and terahertz wave based imaging techniques with great potential for NDE of load bearing R&S structures, are also discussed in detail. A glimpse of <I>in situ</I> NDE techniques with corresponding experimental setup for R&S structures is also presented. The basic concepts, measurement ranges and their instrumentation, measurement method of different R&S structures and some miscellaneous topics are discussed in detail. Some of the challenges and issues pertaining to the measurement of curved R&S structures are also presented. This study also lists various mathematical models and analytical techniques for the electromagnetic performance evaluation and NDE of R&S structures. The research directions described in this study may be of interest to the scientific community in the aerospace sectors.</P>

Microwave absorption properties of FSS-impacted composites as a broadband microwave absorber

Panwar, Ravi,Puthucheri, Smitha,Singh, Dharmendra,Agarwala, Vijaya,Lee, Jung-Ryul VSP 2017 Advanced Composite Materials Vol. No.

Modulational instability of a laser pulse in a non-uniform plasma channel

Panwar, Anuraj,Ryu, Chang-Mo,Kumar, Ashok Cambridge University Press 2016 Laser and particle beams Vol.34 No.1

<B>Abstract</B><P>A self-guided Gaussian laser pulse propagating in a non-uniform plasma channel is unstable to a plasma wave perturbation co-moving with the laser with its group velocity. The plasma wave amplitude has a maximum radial profile along the laser propagation axis. As the plasma wave propagates through a non-uniform plasma channel, the plasma wave perturbation causes focusing in the part of the laser that propagates with the electron density trough and defocusing in the part moving with the crest. This yields an axial gradient in the intensity of the laser and produces a ponderomotive force on the electrons. The ponderomotive force drives the plasma wave, which in turn makes the modulational instability grow. The growth rate of the modulational instability becomes larger with the increase in non-uniformity of a shallow plasma channel. In a deep cavitated plasma channel the growth rate of the modulational instability increases with the laser pulse amplitude.</P>