Argon ion implanted CR-39 polymer: Optical and structural characterization Preeti Chhokkar, V. Kumar, Parveen K. Goyal, Shyam Kumar, A.K. Tomar, Anurag Gaur, Anil Arya Optical Materials, 2021 The samples of Polyallyl diglycol Carbonate (CR-39) were implanted with 100 keV argon ions at fluences 1 × 1015, 5 × 1015 and 1 × 1016 ions/cm2 to be employed for optical and structural studies. The changes in transmittance, reflectance, optical energy gap and refractive index have been studied through the UV–Vis–NIR spectroscopic technique. The enhancement in reflectivity and a strong reduction in transmittance, particularly in the UV region, are observed after Ar+ implantation in CR-39 samples. The absorbance value remains low ~0.10, 0.15 and 0.20 in the key communication wavelength region i.e. 800–1600 nm for sample implanted at the fluence of 1 × 1015, 5 × 1015, 1 × 1016 Ar+/cm2, respectively. The Optical energy gap (EOPT) is determined to be 0.92 eV for the implanted layer of the sample implanted at the fluence of 1 × 1016 Ar+/cm2, whereas 3.70 eV for the pristine sample. The surface electrical conductivity is increased from ~1.49 × 10−14 S (pristine sample) to ~8.34 × 10−10 S for sample implanted at the fluence of 1 × 1016 Ar+/cm2. The formation of conjugated π-bond (-C C-) structure with Ar+ implantation is confirmed via FTIR and Raman measurements. TGA results are analysed in detail and are found to be in strong agreement with the changes observed in different properties of CR-39 after ion implantation.
Optical and electrical properties of UV irradiated PVA/Ag nanocomposites Rishi Pal Chahal, Suman Mahendia, A. K. Tomar, Shyam Kumar Aip Conference Proceedings, 2019 Silver nanoparticles embedded Polyvinyl alcohol (PVA) nanocomposites samples were prepared by in‒situ chemical reduction of silver nitrate (AgNO3) in an aqueous solution of PVA. The prepared nanocomposite films were exposed to ultraviolet (UV) radiations for different times at room temperature. The UV irradiation induced modification has been studied through optical spectroscopy and electrical measurements. The appearance of Surface Plasmon Resonance (SPR) band at 425 nm in the UV-Visible absorption spectra of PVA/Ag nanocomposite confirms the presence of the silver nanoparticles in PVA matrix. The optical energy gap values were found to reduce from 4.92 eV in pure PVA to 4.61 eV for PVA/Ag nanocomposites without UV irradiation, which further reduces to 4.40 eV after UV irradiation for 240 minutes. Such a reduction in optical energy gap may be linked to the increased conjugation in PVA matrix as an effect of embedding of silver nanoparticles. The value of conductivity increases from 4.16 × 10‒9 S/m for pure PVA to 3.64 × 10‒8 S/m for PVA/Ag nanocomposites which further enhances with the increase of UV exposure.
DC conductivity and charge transportation in PMMA and CSA doped polyaniline composites A. K. Tomar, Suman Mahendia, Rishipal Chahal, Shyam Kumar Aip Conference Proceedings, 2019 In the present work, Polyaniline doped with Camphor sulfonic acid (CSA) has been synthesized chemically using oxidative polymerization of Aniline taking Ammonium persulfate (APS) as oxidant. The molar ratio of Aniline:CSA:APS was kept as 1:1:1. The conductivity of Polyaniline powder was determined and found to be 4.93 S/cm. The as prepared powder was blended with PMMA at different concentrations using solution casting method taking chloroform as solvent. Their dc conductivity and charge transportation mechanism was analyzed through I-V measurements. A sudden jump of ∼6 orders has been observed in dc conductivity on mixing of 10% by weight of PAni.CSA in PMMA. Furthermore, the charge transportation is also found to be shifting to Poole-Frankel mechanism, which is through Schottky-Richardson mechanism in pure PMMA, on increasing the concentration of PAni.CSA in PMMA.
Electrical studies of PMMA blended with iron loaded polyaniline A. K. Tomar, Suman Mahendia, Rishipal Chahal, Shyam Kumar Aip Conference Proceedings, 2019 The blending of polyaniline (PAni) with insulating polymers is an active area of research which has been driven by the possibility to combine the good mechanical properties and processability of the polymer matrix with low electrical resistance. The present paper focuses on the electrical and optical behavior of Poly(methyl methacrylate) (PMMA) blended with different weight percent of PAni loaded with iron (Pani.Fe). We have synthesized PAni.Fe via oxidative chemical polymerization method using Ammonium Persulphate (APS) as oxidant. The conductivity of PAni.Fe powder was found to be 3.53⨯10−2 S/cm. Free standing films of PMMA-PAni.Fe blends were obtained through mixing of different weight % of as prepared PAni.Fe powder with PMMA by solution casting method taking Chloroform as solvent. In order to find the optical characteristics of blended films, these were subjected to UV-Visible-NIR spectroscopy. Conductivity and charge transportation behavior of these blends were analysed through V-I measurements. The optical energy gap of PMMA-PAni.Fe films was found to be reduced to 1.81 eV from 2.72 eV (pure PMMA) and dc conductivity is improved by 6 order in magnitude, with the addition of 10 wt. % of PAni.Fe in PMMA. The charge transportation, which is through Schottky-Richardson conduction mechanism for pure PMMA and its blends with lower concentrations of PAni.Fe also starts shifting towards Poole-Frenkel mechanism as the concentration of PAni.Fe is increased in PMMA-PAni.Fe blends.The blending of polyaniline (PAni) with insulating polymers is an active area of research which has been driven by the possibility to combine the good mechanical properties and processability of the polymer matrix with low electrical resistance. The present paper focuses on the electrical and optical behavior of Poly(methyl methacrylate) (PMMA) blended with different weight percent of PAni loaded with iron (Pani.Fe). We have synthesized PAni.Fe via oxidative chemical polymerization method using Ammonium Persulphate (APS) as oxidant. The conductivity of PAni.Fe powder was found to be 3.53⨯10−2 S/cm. Free standing films of PMMA-PAni.Fe blends were obtained through mixing of different weight % of as prepared PAni.Fe powder with PMMA by solution casting method taking Chloroform as solvent. In order to find the optical characteristics of blended films, these were subjected to UV-Visible-NIR spectroscopy. Conductivity and charge transportation behavior of these blends were analysed through V-I measurements. The...
Gamma irradiation induced modification in optical behaviour of PVA/Ag nanocomposite films Rishi Pal Chahal, Suman Mahendia, A. K. Tomar, Anand Malik, Hitender Kumar, Shyam Kumar Aip Conference Proceedings, 2019 Polymer metal nanocomposites draw attention due to their potential applications in the field of optics. In the present work, PVA/Ag nanocomposites were prepared by in‒situ chemical reduction method and afterward irradiated with gamma rays at various doses. The optical properties of PVA/Ag nanocomposite films before and after gamma irradiation at different doses were investigated. The decline in transmission intensity of PVA/Ag nanocomposite films after gamma irradiation in different wavelength ranges may be utilized to block a particular wavelength/range of wavelengths.Polymer metal nanocomposites draw attention due to their potential applications in the field of optics. In the present work, PVA/Ag nanocomposites were prepared by in‒situ chemical reduction method and afterward irradiated with gamma rays at various doses. The optical properties of PVA/Ag nanocomposite films before and after gamma irradiation at different doses were investigated. The decline in transmission intensity of PVA/Ag nanocomposite films after gamma irradiation in different wavelength ranges may be utilized to block a particular wavelength/range of wavelengths.
PVA-Ag nanocomposite: As glucose sensing material Suman Mahendia, A. K. Tomar, P.K. Goyal, Rajesh Kumar, Shyam Kumar Proceedings Ispts 1 1st International Symposium on Physics and Technology of Sensors, 2012
Thermal properties of PMMA doped with polyaniline A. K. Tomar, Suman Mahendia, Rishi Pal Chahal, Shyam Kumar, S. K. Tripathi, Keya Dharamvir, Ranjan Kumar, G. S. S. Saini Aip Conference Proceedings, 2011
Effect of ultraviolet irradiation on the optical and structural characteristics of in-situ prepared pvp-ag nanocomposites Digest Journal of Nanomaterials and Biostructures, 2011
Effect of ultraviolet irradiation on the optical and structural characteristics of in-situ prepared PVP-ag nanocomposites Optoelectronics and Advanced Materials Rapid Communications, 2010
