Effect of TiO2 nano‐filler on the electrical conductivity and free volume parameters of PSAN/TiO2 nanocomposites

To explore the effect of filler on the electrical conductivity of polymer nanocomposites, polystyrene co‐acrylonitrile and TiO2 (PSAN/TiO2) nanocomposites of different TiO2 wt% have been prepared. The microstructural characterization has been performed by positron annihilation lifetime spectroscopy (PALS). Positron lifetime parameters viz. o‐Ps lifetime (τ3) and free volume size (Vf) decreases up to 0.6 wt% suggests the filling of the cavities by Ti3+ and O− ions as well as complex formation. The increased free volume size (Vf) after 0.6 wt% of TiO2 was attributed to the o‐Ps annihilation at the interface of PSAN and TiO2 nanoclusters. The variation of electrical conductivity at lower and higher concentration of TiO2 is attributed to the blocking effect and space charge effect, respectively. The electrical conductivity decreases along with the free volume sizes at lower concentration of TiO2 due to the hindrance of the ions mobility. The increased conductivity with the increased free volume sizes indicates the formation of more void space at the interface due to the formation of TiO2 nanoclusters. The surface morphology of the nanocomposites studied by scanning electron microscopy (SEM) shows uniform dispersion at the lower wt% of TiO2 and increased size of nanocluster formation at the higher concentration of TiO2 nanoparticles in PSAN matrix. The crystallinity evaluated by X‐ray diffraction (XRD) results also indicates the formation of TiO2 nanoclusters between 0.6 and 1.0 wt% of TiO2. Fourier transform infrared spectroscopy (FTIR) suggests the improved chemical and physical interaction between the functional groups of TiO2 and polymer side chain. POLYM. COMPOS., 39:1403–1412, 2018. © 2016 Society of Plastics Engineer

Ionic and electronic transport in PSF/NiO and PSF/TiO2 polymer nanocomposites: a positron lifetime study

Polymer nanocomposites of PSF/NiO and PSF/TiO2 with different wt of nanofiller have been prepared and subjected to SEM, FTIR, X-ray diffraction, DSC, PALS and electrical conductivity measurements. The relationship between crystallinity, surface morphology, glass transition temperature, free volume and the electrical conductivity of these polymer nanocomposites was systematically investigated. The increased AC and DC electrical conductivity at the lower concentration of NiO suggests the increased number of mobile ions and electrical charge carriers due to the increased crystallinity of PSF/NiO composites. The decreased conductivity at higher concentration of NiO indicates the reduced conducting pathways for the mobility of ions and the electrical charge carriers due to the decreased crystallinity by the nanoparticles aggregations. The increased AC and DC electrical conductivity with increasing the concentration of TiO2 indicates more and more positive charges in front of the cathode, resulting proper polymer-nanofiller interface due to the conductivity chain formation through the nanoparticles aggregation. The surface morphology of PSF/NiO and PSF/TiO2 nanocomposites show dispersion of nanoparticles over the surface of PSF matrix and the formation of filler aggregates at higher wt of nanofiller incorporation. The increased glass transition temperature (Tg) and decreased o-Ps lifetime (τ3) at the lower concentration of NiO and TiO2 indicates the improved interfacial interaction between the surface of NiO and TiO2 nanoparticles with the side chains of PSF polymer matrix. This is evident from Fourier Transform Infrared Spectroscopy (FTIR) studies. The increased o-Ps lifetime (τ3) at higher concentration of NiO and TiO2 suggests the increased interfacial space for o-Ps to annihilate at the interface of PSF and NiO and TiO2 nanoclusters

Studies on free volume controlled electrical properties of PVA/NiO and PVA/TiO2 polymer nanocomposites

Microstructural characterization of poly(vinyl alcohol)/nickel oxide (PVA/NiO) and titanium dioxide (PVA/TiO2) polymer nanocomposites has been performed by Positron Lifetime Technique (PLT). The increased positron lifetime parameter viz., o-Ps lifetime (τ3) up to 1.0 wt of NiO and up to 0.4 wt of TiO2 loading suggests the reduction in overall packing density of the polymer network and the formation of interface between PVA polymer matrix and NiO, TiO2 nanoclusters. The decreased o-Ps lifetime (τ3) at the higher concentration of TiO2 loading indicates the improved interfacial interaction between the surface of TiO2 nanoparticles and side chain of PVA polymer matrix. This is evident from Fourier Transform Infrared Spectroscopy (FTIR) studies. Scanning Electron Microscopy (SEM) studies demonstrate the formation of nanoclusters by the agglomeration of nanoparticles at higher wt of nanofiller loading. The increased AC/DC conductivity of PVA/NiO and at lower concentration of TiO2 in PVA/TiO2 polymer nanocomposites suggests the increased mobility of ions and electric charge carriers. The decreased conductivity at higher concentration of TiO2 indicates the reduced conducting pathways for the mobility of ions and electric charge carriers due to the increased ion aggregation. The increased dielectric constant and dielectric loss up to 1.0 wt of NiO and 0.4 wt of TiO2 suggests the increased dipole polarization. The decreased dielectric constant after 0.4 wt of TiO2 is attributed to the reduced dipole polarization by the formation of thin immobile nano-layers and hence the polymeric chain mobility

Studies on free volume controlled electrical properties of PVA/NiO and PVA/TiO2 polymer nanocomposites

Microstructural characterization of poly(vinyl alcohol)/nickel oxide (PVA/NiO) and titanium dioxide (PVA/TiO2) polymer nanocomposites has been performed by Positron Lifetime Technique (PLT). The increased positron lifetime parameter viz., o-Ps lifetime (τ3) up to 1.0 wt of NiO and up to 0.4 wt of TiO2 loading suggests the reduction in overall packing density of the polymer network and the formation of interface between PVA polymer matrix and NiO, TiO2 nanoclusters. The decreased o-Ps lifetime (τ3) at the higher concentration of TiO2 loading indicates the improved interfacial interaction between the surface of TiO2 nanoparticles and side chain of PVA polymer matrix. This is evident from Fourier Transform Infrared Spectroscopy (FTIR) studies. Scanning Electron Microscopy (SEM) studies demonstrate the formation of nanoclusters by the agglomeration of nanoparticles at higher wt of nanofiller loading. The increased AC/DC conductivity of PVA/NiO and at lower concentration of TiO2 in PVA/TiO2 polymer nanocomposites suggests the increased mobility of ions and electric charge carriers. The decreased conductivity at higher concentration of TiO2 indicates the reduced conducting pathways for the mobility of ions and electric charge carriers due to the increased ion aggregation. The increased dielectric constant and dielectric loss up to 1.0 wt of NiO and 0.4 wt of TiO2 suggests the increased dipole polarization. The decreased dielectric constant after 0.4 wt of TiO2 is attributed to the reduced dipole polarization by the formation of thin immobile nano-layers and hence the polymeric chain mobility

Free volume dependence on electrical properties of Poly (styrene co-acrylonitrile)/Nickel oxide polymer nanocomposites

Polymer nanocomposites of Poly (styrene co-acrylonitrile)/Nickel Oxide (PSAN/NiO) have been prepared. The increased free volume sizes up to 0.4 wt of NiO loading indicates overall reduction in packing density of polymer network. The decreased o-Ps lifetime (τ3) at higher concentration of NiO indicates improved interfacial interaction between the surface of NiO nanoparticles and side chain of PSAN polymer matrix. The increased AC/DC conductivity at lower wt of NiO loading demonstrates increased number of electric charge carriers/mobile ions and their mobility. The increased dielectric constant and dielectric loss up to 0.4 wt of NiO loading suggests the increased dipoles polarization

Electron beam induced microstructural changes and electrical conductivity in bakelite polymer rpc detector material: a positron lifetime study

In order to explore the structural modification induced electrical conductivity, samples of Bakelite RPC polymer detector materials were exposed to 8 MeV of electron beam with the irradiation dose from 20 kGy to100 kGy in steps of 20 kGy. The microstructural changes upon electron beam irradiation have been studied using Positron Annihilation Lifetime Spectroscopy (PALS) and Fourier Transform Infrared (FTIR) Spectroscopy. Positron lifetime parameters viz., o-Ps lifetime and its intensity show chain scission at lower doses (20 kGy, 40 kGy) followed by cross-linking beyond 40 kGy due to the radical reactions. The reduction in electrical conductivity of Bakelite material beyond 60 kGy is correlated to the conducting pathways and cross-links in the polymer matrix. The appropriate doses of electron beam irradiation of Bakelite material may reduce the leakage current and hence improves the performance of the detecto

Detection of genetically modified cotton seeds using PCR and real-time PCR

176-181Detection of genetically modified (GM) crops and products are necessary to comply with international labeling regulations and to avoid spurious and unapproved GM planting. DNA based analytical tools involving PCR and real-time PCR were used to detect GM cotton seeds. Four pairs of primers specific for CaMV 35S, Nos, nptII and cry1Ac genes were used for the DNA detection of GM crop. The limit of detection in real-time PCR was found to be 0.1%. Evidently, these two PCR techniques were successful in detecting transgenes in the DNA of GM cotton seeds

Detection of genetically modified cotton seeds using PCR and real-time PCR

176-181Detection of genetically modified (GM) crops and products are necessary to comply with international labeling regulations and to avoid spurious and unapproved GM planting. DNA based analytical tools involving PCR and real-time PCR were used to detect GM cotton seeds. Four pairs of primers specific for CaMV 35S, Nos, nptII and cry1Ac genes were used for the DNA detection of GM crop. The limit of detection in real-time PCR was found to be 0.1%. Evidently, these two PCR techniques were successful in detecting transgenes in the DNA of GM cotton seeds