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Biopolymer blend nanocomposite films composed of polyvinyl alcohol (PVA) and chitosan (CS) with varying quantities of hydroxyapatite (HA) nanoparticles were developed using a green solution casting method. The formation of blend nanocomposite was confirmed by Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible (UV) spectrometer, field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Mechanical parameters such as tensile strength, percentage elongation at break, hardness, dielectric constant, and temperature-dependent alternating current (AC) conductivity were analyzed. The bonding between the nanoparticles and PVA/CS blend was verified by the shift in distinctive peaks of blend in the nanocomposites to a higher wavenumber in the FTIR spectra. The UV spectra demonstrated the difference in absorbance and transmittance of the PVA/CS blend with the reinforcement of HA nanofillers. The bandgaps of the nanocomposites marginally decreased with an increase in nanoparticle loading. The SEM and XRD patterns revealed the ordered arrangement of the blend matrix due to the presence of nanoparticles. The assessment of thermal characteristics obtained from DSC and TGA demonstrated a clear increase in phase transition temperature and thermal stability of nanocomposites. The electrical conductivity measurement indicated a rise in dielectric constant and AC conductivity of blend nanocomposites with the addition of nanoparticles. The temperature-dependent AC conductivity showed a reduction in activation energy as temperature and nanoparticle loading increased. The tensile strength and surface hardness of the PVA/CS blend nanocomposite increased with the dosage of HA content in the blend matrix. Highlights * A series of polyvinyl alcohol (PVA)/chitosan (CS)/hydroxyapatite (HA) nanocomposites were prepared by the green method * Enhanced optical property, thermal stability, and glass transition temperature * Possess excellent dielectric constant and alternating current conductivity * The inclusion of HA increased the mechanical strength of the PVA/CS blend * A potential blend nanocomposite for flexible optoelectronic and charge storage devices. KEYWORDS AC conductivity, chitosan, crystallinity, dielectric constant, hydroxyapatite, polyvinyl alcohol, tensile strength, thermal properties, 1 | INTRODUCTION In recent years, many additional breakthroughs have been achieved to reduce environmental threats and crises. The development of economically and environmentally friendly polymers and their enhanced production [...]

A series of copolymer nanocomposites based on poly(aniline-co-pyrrole) (PANI-co-PPy) with different contents of copper alumina (Cu-[Al.sub.2][O.sub.3]) nanoparticles were synthesized by benign in situ chemical oxidation polymerization. The structural, thermal transition, and morphological interpretations were carried out by Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), differential scanning calorimetry (DSC), and high-resolution transmission electron microscope (HR-TEM). The electrical properties such as alternating current (AC) conductivity and dielectric measurements were performed at room temperature to verify their application in developing new electronic devices. The presence of nanoparticles in the copolymer and the synergistic interaction in the copolymer matrix was confirmed by FTIR and XRD. HR-TEM indicates the nanosized uniform dispersion of nanofiller in the copolymer matrix. DSC revealed a reduction in the flexibility of polymer with an increase in glass transition temperature of copolymer composites. AC conductivity measurement manifested an increased hopping of charge carriers in nanocomposites when compared with pristine PANI-co-PPy. Dielectric properties were maximum for copolymer with 5 wt% Cu-[Al.sub.2][O.sub.3]. Excellent gas sensing traits were observed for copolymer nanocomposites due to the electron transfers existing between PANI-co-PPy and ammonia gas. The maximum gassensing properties and electrical conductivity were observed for 5 wt% copolymer composites. The magnificent material properties make PANI-co-PPy/Cu[Al.sub.2][O.sub.3] nanocomposites, a promising contender for developing nano-electronic devices. KEYWORDS conductivity, copper alumina, dielectric properties, gas sensing, nanocomposites, poly (aniline-co-pyrrole), 1 | INTRODUCTION In the recent era, usage of energy is increasing exponentially while energy storage is always a challenge. Conducting polymers with excellent electrical and dielectric properties are a [...]

This article reports the facile synthesis of copper sulfide (CuS)/polyaniline (PANI) nanocomposites by in situ polymerization. The composites were characterized by scanning electron microscopy (SEM), UV-visible and Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). SEM analysis showed that the metal sulfide nanoparticles were uniformly dispersed in the polymer matrix. The characteristic peaks in FTIR and UV-vis spectra of PANI were found to be shifted to higher wave numbers in PANI/CuS composite, which is attributed to the interaction of CuS nanoparticles with PANI chain. XRD pattern revealed the structurally ordered arrangement of polymer composite and this regularity increases with increase in concentration of nanoparticles. Glass transition temperature of the nanocomposite increased with increase in the concentration of nanoparticles and it indicated the ordered arrangement of the polymer composite than PANI. TGA studies indicated excellent thermal stability of polymer nanocomposite. The electrical properties of nanocomposites were studied from direct current and alternating current resistivity measurement. Conductivity, dielectric constant, and dissipation factor of the nanocomposite were significantly increased with the increase in CuS content in the nanocomposite. The enhancement of these properties suggests that the proposed PANI/CuS nanocomposites can be used as multifunctional materials for nanoelec-tronic devices. POLYM. ENG. SCI., 54:438-445, 2014. © 2013 Society of Plastics Engineers, INTRODUCTION For a polymer to become electrically conductive, it must imitate a metal which means that electrons in polymers must be free to move. The electrical property of polymeric materials [...]

In this study, nanocomposites of cashew tree gum (CTG) encapsulated nano-magnetite (Fe3O4) was prepared and characterized by FTIR, UV-visible, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), magnetic and conductivity measurements. The characteristic absorption peaks in FTIR and UV-vis spectra of CTG was found to be shifted to higher wave numbers in CTG/Fe3O4 composite, which is due to the intermolecular interaction between nanoparticles and the CTG. The XRD patterns indicated that amorphous region of gum was decreased by the addition of metal oxide nanoparticles. SEM images show that nano-Fe3O4 was uniformly dispersed in the cashew gum segments. DSC analysis revealed that the glass transition temperature and melting behavior of composites were higher than those of the pure gum. TGA results indicated that the thermal decomposition temperature of the composite increases with the increase in concentration of metal oxide nanoparticles. The magnetic properties studied by a vibrating sample magnetometer indicate that electromagnetism of CTG/Fe3O4 nanocomposites were superparamagnetic. The values of saturation of magnetization ( Ms) and remanence ( Mr) increases, while the coercivity (Hc) decreased with increase in Fe3O4 content in the composite. The AC electrical conductivity of the nanocomposites was significantly increased with the increase in Fe3O4 content in the nanocomposite. Due to the ordered structure of polymer composite, the dielectric constant and dielectric loss tangent (tan δ) of nanocomposites were also increased with increase in the concentration of nanoparticles. POLYM. COMPOS., 38:E66-E73, 2017. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]