Synthesis,characterisation and flame,thermal and electrical properties of poly (<Emphasis Type="Italic">n</Emphasis>-butyl methacrylate)/titanium dioxide nanocomposites

Nanocomposites based on poly (n-butyl methacrylate) (PBMA) with various concentrations of titanium dioxide (TiO₂) nanoparticles were synthesised by in situ free radical polymerisation method. The formation of nanocomposite was characterised by FTIR, UV, XRD, DSC, TGA, impedance analyser and flame retardancy measurements. FTIR and UV spectrum ascertained the intermolecular interaction between nanoparticles and the polymer chain. The XRD studies indicated that the amorphous region of PBMA decreased with the increase in content of metal oxide nanoparticles. The SEM revealed the uniform dispersion of nanoparticles in the polymer composite. The DSC and TGA studies showed that the glass transition temperature and thermal stability of the nanocomposites were increased with the increase in the concentration of nanoparticles. The conductivity and dielectric properties of nanocomposites were higher than pure PBMA and the maximum electrical property was observed for the sample with 7 wt% TiO₂. As the concentration of nanoparticles increased above 7 wt%, the electrical property of nanocomposite was decreased owing to the agglomeration of nanoparticles in the polymer. Nanoparticles could impart better flame retardancy to PBMA/TiO₂ composite and the flame resistance of the materials improved with the addition of nanoparticles in the polymer matrix.     

Structural,electrical, thermal,and gas sensing properties of new conductive blend nanocomposites based on polypyrrole/phenothiazine/silver‐doped zinc oxide

The main aim of this study is to investigate the effect of silver‐doped zinc oxide (Ag‐ZnO) loading on the structural, morphological, thermal and electrical properties, and gas sensing behavior of polypyrrole (PPy)/phenothiazine (PTZ)‐blend nanocomposites. The composites are characterized by FTIR, XRD, SEM, TEM, DSC, TGA, and impedance studies. FTIR spectra exhibit the presence of Ag‐ZnO in the PPy/PTZ blend. XRD analysis shows that the semicrystalline behavior of the polymer blend is greatly enhanced by the addition of Ag‐doped ZnO particles. Uniform dispersion of nanoparticles in the polymer is obtained from SEM analysis. The TEM images confirm the presence of spherically shaped nanoparticles in PPy/PTZ blend with a size of 10–25 nm. The DSC measurement indicates that the glass transition temperature of PPy/PTZ blend was significantly improved in the presence of Ag‐doped ZnO nanoparticles. The thermal decomposition temperature of nanocomposite obtained from TGA shows an increase with increase in the content of Ag‐ZnO particles. The incorporation of Ag‐doped ZnO nanoparticles to PPy/PTZ blend exhibit increase in the AC conductivity and dielectric properties of the nanocomposite, due to the pilling of charges at the extended interface of the composite system. The DC conductivity of the nanocomposite increases with the loading of nanoparticles. The ammonia gas sensing performance of PPy/PTZ/Ag‐ZnO nanocomposite is analyzed, and the result shows that the fabricated blend composite can be used as a promising candidate for the easy access of gas molecules. J. VINYL ADDIT. TECHNOL., 26:187–195, 2020. © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers.     

Role of copper alumina nanoparticles on the performance of polyvinylchloride nanocomposites

Poly(vinyl chloride) (PVC) nanocomposites with different contents of copper alumina (Cu-Al₂O₃) nanoparticles were prepared by the solution casting method. The effects of the nanoparticles on structural, thermal, electrical, contact angle and mechanical properties were thoroughly examined. The presence of Cu-Al₂O₃ in the macromolecular chain was confirmed through Fourier transform infrared (FTIR) spectroscopy. The X-ray diffraction (XRD) analysis of PVC nanocomposites showed the systematic arrangement of Cu-Al₂O₃ nanoparticles within the polymer, which indicated the higher crystallinity of the nanocomposites. The surface morphology of PVC was changed into hemispherical shaped particles by the inclusion of nanofiller was analyzed from SEM images. The glass transition temperature of the nanocomposites obtained from differential scanning calorimetry (DSC) was found to be increased with an increase in loading of nanoparticles in the polymer. The AC conductivity and dielectric studies revealed that the inclusion of nanofiller increases the electrical properties of the material and the composite with 7 wt.% sample showed the maximum conductivity and dielectric constant. The mechanical properties such as modulus, tensile strength, hardness, and impact properties of the PVC nanocomposites were significantly enhanced by the reinforcement of nanoparticles into the PVC matrix. The reinforcing mechanism behind the increase in tensile strength with the addition of nanoparticles was correlated with different theoretical models. The highest mechanical and electrical properties were observed for 7 wt.% Cu-Al₂O₃ loaded nanocomposite. Contact angle measurements of PVC with various loadings of Cu-Al₂O₃ nanofillers demonstrated that the nanoparticle attachment increased the hydrophobicity of the polymer matrix.     

Facile synthesis,characterization and material properties of a novel poly(vinyl cinnamate)/ nickel oxide nanocomposite

A poly(vinyl cinnamate) (PVCin) composite was synthesized by a simple one step in situ polymerization of vinyl cinnamate with nickel oxide (NiO) nanoparticles. The structural, morphological and thermal properties of the nanocomposite were characterized using Fourier transform (FT)‐Raman, FT infrared (FTIR) and UV spectroscopies, X‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry and vibrating sample magnetometry (VSM) measurements. FT‐Raman, FTIR and UV spectroscopy results revealed the characteristic absorption and shifts of peaks of the polymer matrix, the shifts being attributed to the interaction of NiO nanoparticles with the polymer chains. The structural and morphological analysis using XRD, HRTEM and FESEM showed the uniform arrangement of nanoparticles within the polymer chains. VSM showed the ferromagnetic nature of the composite with an increasing saturation of magnetism. The glass transition temperature (T_g) of the composite was higher than that of pure PVCin and T_g of the composite increased with increasing nanoparticle content. The electrical resistivity of the nanocomposite was studied from AC and DC conductivity measurements. AC and dielectric properties were markedly enhanced in the whole range of frequency due to the presence of NiO nanoparticles. DC conductivity of the nanocomposite was much higher than that of PVCin and the conductivity of the nanocomposite increased with increasing content of NiO nanoparticles. © 2016 Society of Chemical Industry     

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Hydroxyapatite nanoparticles (HA) reinforced polymer blend based on chlorinated nitrile rubber (Cl-NBR) and chlorinated ethylene propylene diene monomer rubber (Cl-EPDM) were prepared. Resulting blend composites were analyzed with regard to their rheometric processing, crystallinity, glass transition temperature (T_g), mechanical properties, oil resistance, AC conductivity, and transport behavior. The decrease in optimum cure time with the addition of HA is more advantageous for the development of products from these blend nanocomposites. The XRD, FTIR, and SEM confirmed the attachment and uniform dispersion of HA nanoparticles in the Cl-NBR/Cl-EPDM blend. The good compatibility between polymer blend and nanoparticles was also deduced by the formation of spherically shaped HA particles in the blend matrix determined by TEM analysis. DSC analysis showed an increase in T_g of the blend with the filler loading. The addition of HA particles to the blend produced a remarkable increase in tensile and tear strength, hardness, AC conductivity, abrasion, and oil resistance. The diffusion of blend composites was decreased with an increase in penetrant size. The diffusion mechanism was found to follow an anomalous trend. Among the blend composites, the sample with 7 phr of HA not only showed good oil and solvent resistance but also a remarkable increase in AC conductivity and mechanical properties.     

Synthesis,characterization, and properties of new conducting polyaniline/copper sulfide nanocomposites

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 nanoelectronic devices. POLYM. ENG. SCI., 54:438–445, 2014. © 2013 Society of Plastics Engineers     

Synthesis,characterization, and conductivity studies of polypyrrole/copper sulfide nanocomposites

Nanocomposites of polypyrrole (PPy) containing copper sulfide (CuS) were synthesized by an in situ chemical oxidative polymerization. The nanocomposites were characterized by FTIR, SEM, XRD, DSC, TGA, and conductivity studies. The FTIR spectra ascertained the chemical interlinking of polypyrole with metal sulfide nanoparticles. Morphological analysis showed that the nanoparticles were uniformly covering the entire substrate. The XRD pattern reveals that the nanoparticle incorporated polypyrrole showed a crystalline nature and the crystallinity of the polymer increases with increase in concentration of CuS nanoparticles. From DSC, an increase in glass transition temperature shows the increased orderness in the polymer composite than in the pure polypyrrole. Thermal analysis (TGA) of the composite showed a progressive increase in the thermal stability with increase in content of CuS. The frequency dependent electrical properties (a.c. conductivity) of the nanocomposites were higher than that of polypyrrole. The d.c. electrical conductivity increased with increase in amount of nanoparticles in the polymer matrix. The results obtained for these composites have greater scientific and technological interest. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Fabrication and characterization of conducting nanomaterials composed of copper sulfide and polyindole

Conducting polymer nanocomposites of polyindole (PIN)/copper sulfide (CuS) were fabricated by in situ polymerization of indole with different concentration of CuS nanoparticles. These composites were examined by X‐ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and electrical studies. XRD analysis confirmed that the composite began to crystallize by the incorporation of CuS nanoparticles. The IR spectrum shows the intermolecular interaction between PIN and CuS. SEM images revealed that the nanoparticles were uniformly embedded in the entire substrate. Glass transition temperature was found to be increased with increase in concentration of nanoparticles, which showed an ordered structure of the samples. TGA results indicated that the fabricated PIN/CuS composite attains better thermal stability than pure PIN. The dc conductivity of nanocomposite was significantly increased with increase in content of CuS nanoparticle. An increase in ac electrical conductivity and dielectric properties of the composite were observed with increase in molar concentration of CuS nanoparticles. Thus, enhancements in these properties suggest that the fabricated PIN/CuS nanocomposite has potential application in the field of nanotechnology. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Synthesis,characterization, and properties of cashew gum graft poly(acrylamide)/magnetite nanocomposites

Graft copolymer nanocomposites based on cashew gum and poly(acrylamide) with different concentrations of nano‐iron‐oxide particles (Fe₃O₄) have been prepared by an in situ polymerization method. The characterization of graft copolymer composite was carried out by FTIR, UV, XRD, SEM, DSC, and TGA, electrical conductivity, and magnetic property [vibrational sample magnetometer (VSM)] measurements. The shift in the spectrum of UV and FTIR peaks shows the intermolecular interaction between metal oxide nanoparticles and the graft copolymer system. The spherically shaped particles observed from the SEM images clearly indicating the uniform dispersion of nanoparticles within the graft copolymer chain. The XRD studies revealed that the amorphous nature of the graft copolymer decreases by the addition of Fe₃O₄ nanoparticles. The glass transition temperature studied from DSC increases with increase in concentration of metal oxide nanoparticles. Thermal stability of composite was higher than the pure graft copolymer and thermal stability increases with increase in content of nanoparticles. Electrical properties such as AC conductivity and dielectric properties of the composites increased with increase in concentration of metal oxide nanoparticles. The magnetic property of graft copolymer nanocomposites shows ferromagnetic and supermagnetism and the saturation of magnetism linearly increased with increasing the Fe₃O₄ content in the polymer composite. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43496.     

Dynamic mechanical properties,magnetic and electrical behavior of iron oxide/ethylene vinyl acetate nanocomposites

Nanocomposites of ethylene vinyl acetate (EVA) containing iron oxide nanoparticles (IONPs) were prepared by open mill‐mixing technique. The effect of loading of IONPs in EVA was characterized by Fourier transform infrared (FTIR), X‐ray diffraction (XRD), transmission electron micrograph (TEM), and dynamic mechanical analysis (DMA). The FTIR spectra ascertain the intermolecular interaction between the polymer and IONPs. TEM and XRD studies revealed the structurally ordered arrangement of nanoparticles within the polymer matrix. DMA showed an increase in storage modulus and lesser damping characteristics of composite with the increase in loading of nanoparticles, whereas these properties decreased significantly with increase in temperature. The glass transition temperature shifted toward higher temperature with the increase in content of IONPs. Magnetic properties of the nanocomposites were investigated using vibrating sample magnetometer at room temperature. The saturation of magnetization was progressively increased with the increase in content of nanoparticles. The electrical conductivity, dielectric constant, and dielectric loss of the composite were found to be increased with the increase in volume fraction of nanoparticles. The polymer–filler interaction was also determined from the swelling studies. POLYM. COMPOS., 35:1989–1996, 2014. © 2014 Society of Plastics Engineers     

Effect of neodymium‐doped titanium dioxide nanoparticles on the structural,mechanical, and electrical properties of poly(butyl methacrylate) nanocomposites

Nanocomposites based on neodymium‐doped titanium dioxide (Nd‐TiO₂)/poly(n‐butyl methacrylate) (PBMA) have been prepared by an in situ polymerization of butyl methacrylate monomer with varying concentrations of Nd‐TiO₂ nanoparticles. The resulting nanocomposites have been analyzed by ultraviolet (UV)–Visible spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis, and impedance analyzer (TGA). The results of UV and FTIR spectroscopy have indicated the interaction of nanoparticles with the PBMA matrix. Spherically shaped nanoparticles with an average size of 10–25 nm have been revealed in the TEM and their homogeneous dispersion, and interaction of polymer matrix has been confirmed by SEM and XRD studies. The thermal stability and glass transition temperature of the composites were significantly enhanced by the addition of nanoparticles. The AC conductivity and dielectric properties of nanocomposites have been found to be higher than pure PBMA, and the maximum electrical properties have been observed for 7 wt% composite. The reinforcing nature of the nanoparticles in PBMA has been reflected in the improvement in tensile strength measurements. The result indicated that the tensile strength of nanocomposites have greatly enhanced by the addition of Nd‐TiO₂ nanoparticles whereas the elongation at break decreases with the loading of nanofillers. To understand the mechanism of reinforcement, tensile strength values have been correlated with various theoretical modeling. The research has been found to be promising in the development of novel materials with enhanced tensile strength, dielectric constant, and thermal properties, which may find potential applications in energy storage and nanoelectronic devices. J. VINYL ADDIT. TECHNOL., 25:9–18, 2019. © 2018 Society of Plastics Engineers     

Electrical conductivity and electric modulus of stable Kevlar® fiber loaded HAF/NBR rubber composite

DC, AC conductivities and dielectric properties of high abrasion furnace carbon black (HAF)/acrylonitrile butadiene rubber (NBR) composite have been studied with varying the aramide Stable Kevlar^® fiber content, temperature, and frequency. Generally, the electrical conductivity was decreased with increasing Stable Kevlar^® fiber content, which was confirmed by the positron annihilation lifetime spectroscopy. Negative temperature coefficient of conductivity (NTCC) behavior between 353 and 413 K was detected, except for the composite containing 10 phr Kevlar which showed positive temperature coefficient of conductivity (PTCC) behavior above 383 K. These NTCC and PTCC behaviors were further manifested by differential scanning calorimetry (DSC). For the composite with 10 phr Kevlar, the interfacial polarization between the fibers and the polymeric composite can be ascribed to Maxwell‐Wagner‐Sillars mechanism. The (MWS) relaxation disappeared for higher fibers content. The analysis of the electric modulus in the frequency range from 1 kHz to 1 MHz shows that the interfacial relaxation obeys Cole–Davison distribution of relaxation times. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Characterization,conductivity studies,dielectric properties,and gas sensing performance of in situ polymerized polyindole/copper alumina nanocomposites

Conducting polymer composites of polyindole (PIN) and copper–alumina (Cu–Al₂O₃) nanocomposites were synthesized by in situ polymerization of indole with different contents of Cu–Al₂O₃ nanoparticles. The polymer nanocomposites were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmission electron microscope (TEM), differential scanning calorimetry, thermogravimetric analysis, and ammonia gas sensing performance was also analyzed. FTIR and XRD studies revealed the attachment of Cu–Al₂O₃ in the molecular chain of PIN. The presence of bright trapezoid channels and variation in morphology for different loading of nanoparticles were confirmed by SEM and TEM. The attachment of Cu–Al₂O₃ nanoparticles in the PIN matrix was confirmed through EDX spectroscopy. The glass transition temperature and thermal stability of the composites were greatly enhanced with the loading of Cu–Al₂O₃. Enhancement in alternating current conductivity, dielectric constant and the current–voltage characteristics of the prepared composite revealed the semiconducting nature of the system with an increase in the loading of nanoparticles. Also, nanocomposite exhibited an excellent sensitivity and fast response to ammonia gas. The evaluated result of the present study suggested that Cu–Al₂O₃ reinforced PIN hybrid is a good candidate for the fabrication of electrochemical devices.     

Synthesis and characterization of alkali‐soluble photosensitive polysiloxane urethane acrylate

A new negative temperature coefficient of resistor (NTCR) thermistors based on nitrile butadiene rubber/magnetite (NBR/Fe₃O₄) nanocomposites were successfully fabricated by conventional roll milling technique. X‐ray diffraction and transmission (TEM) analysis showed that the product is mainly magnetite nanoparticles with diameter of 10‐13 nm. The microstructure of (NBR/Fe₃O₄) nanocomposites were examined by scanning electron microscopy (SEM) and FTIR spectroscopy. The dispersion of magnetite nanoparticles in the NBR rubber matrix and interfacial bonding between them were rather good. The thermal stability of nanocomposites was also obviously improved with the inclusion of the magnetite nanoparticles. The thermal conductivity, thermal diffusivity and specific heat of nanocomposites were investigated. The electrical conductivity of the NBR/Fe₃O₄ increases with the rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior like a semiconductor. The nature of the temperature variation of electrical conductivity and values of activation and hopping energy, suggest that the transport conduction process is controlled by hopping mechanism. Values of characteristics parameters of the thermistors like thermistor constant, thermistor sensitivity and thermistor stability is quite good for practical application as NTCR devices at high temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation,structure and properties of nitrile–butadiene rubber–organoclay nanocomposites by reactive mixing intercalation method

The nanocomposites of nitrile–butadiene rubber (NBR) and organo‐montmorillonite modified by hexadecyltrimethyl ammonium bromide (HMMT) were prepared by the reactive mixing intercalation method in the presence of the resorcinol and hexamethylenetetramine complex (RH). The structure of the NBR–RH–HMMT nanocomposites was characterized by XRD, TEM, FTIR, determination of crosslinking density, and so on. The results showed that the d‐spacing of HMMT increased substantially with RH addition and the layers of HMMT were dispersed in rubber matrix on a nanometer scale. The mechanical properties of the NBR–RH–HMMT nanocomposites were far superior to those of NBR–HMMT composites, and the glass transition temperature of NBR–RH–HMMT nanocomposite was higher than that of NBR. The reactive mixing intercalation method by introducing RH could enhance the interface combination between the rubber and the organoclay through the interactions of RH with NBR and modified clay. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1905–1913, 2006     

Eco-friendly poly(vinyl alcohol)/delaminated V2C MXene high-k nanocomposites with low dielectric loss enabled by moderate polarization and charge density at the interface

High-dielectric-constant (high-k) polymer/conductor composites with low dielectric loss are desirable for energy storage. However, high leakage currents from interfacial regions with high charge density are difficult to handle. In this work, high permittivity and low dielectric loss were achieved in poly(vinyl alcohol) (PVA)/V₂C MXene nanocomposite films fabricated by solution casting by taking advantage of the interfacial compatibility and moderate interfacial charge density of the nanocomposites. Water-soluble PVA was utilized as the polymer matrix. Delaminated V₂C MXene nanosheets with appropriate conductivity were prepared and used as the filler. The mild interface polarization of the nanocomposites was responsible for achieving favourable permittivity values. The small gap between the work functions of PVA and V₂C contributed to moderate interfacial charge density values and thus low dielectric loss values. A proportional correlation between the interfacial charge density and the conductivity of composites was also verified. The depth of charge injection from the MXene to PVA was found to be half of the interlamellar spacing of the delaminated MXene. The dependence of the electrical properties of the nanocomposites on the frequency and MXene content was also studied. The composite with 4 wt% MXene exhibited a permittivity of ~24 (16 times that of PVA) and a dielectric loss of ~0.14 (1.5 times that of PVA) at 1 kHz, as well as breakdown strength of ~31 MV m⁻¹ (63% of PVA). This work might enable environmentally friendly fabrication of promising composite dielectrics.     

Evaluation of interfacial layer properties in the polystyrene/silica nanocomposite

Processing conditions and final mechanical properties of polymer nanocomposites are affected by their interfacial layers behavior. However, it is impossible to determine directly the properties of these layers by dynamic rheometry tests. In this work, the interfacial layers properties are evaluated for polystyrene containing silica nanoparticles by the concept of glass‐transition temperature shift. The samples were prepared via solution‐mixing method and dynamic rheometry was used to determine the viscoelastic behavior of filled polymers in the melt state. This initial step showed that addition of silica particles increased the glass‐transition temperature. By preference, decrease in the filler particle size lead to a drastic increase in the glass‐transition temperature and interfacial layer volume fraction due to relatively high surface area of the small filler particles. Then, in the next step, the viscoelastic properties of interfacial layer have been evaluated on the basis of the properties of neat polystyrene using temperature‐frequency superposition law. For this purpose, the shift factor was calculated from the glass‐transition temperature of the sample with maximum filler content. Finally, the effect of immobilized interfacial layer on the viscoelastic properties of the polymer nanocomposite samples has been estimated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO₄ electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO₄, heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 × 10⁻⁴ S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO₄ electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications.     

Optical and electrical properties of polyaniline‐cadmium sulfide nanocomposite

Polyaniline‐cadmium sulfide nanocomposite has been synthesized by the chemical oxidative polymerization of aniline with ammonium peroxodisulfate as an initiator in presence of cadmium sulfide nanoparticles. TEM, XRD, FTIR, TGA, UV–vis spectroscopy, and photoluminescence studies were done for the structural, thermal and optical characterization of the samples. The particle size of nanocomposites lies in between 7 and 10 nm. XRD spectrum shows that polyaniline is amorphous, but peaks present in the spectrum of polymer nanocomposites are for cadmium sulfide nanoparticles. TGA result shows that nanocomposite is more thermally stable. The band gap of nanocomposite decreases with increasing content of cadmium sulfide nanoparticles. An enhancement in photoluminescence has been observed in the nanocomposite than that in pure polyaniline. The dc and ac electronic transport property of polyaniline cadmium sulfide composites has been investigated within a temperature range 77 ≤ T ≤ 300 K and in the frequency range 20 Hz–1 MHz. The dc conductivity follows variable range hopping (VRH) model. The ac conductivity follows a power law whereas the temperature dependence of frequency exponent s can be explained by correlated barrier hopping (CBH) model. The dielectric behavior of the samples has been explained in terms of the grain and grain boundary resistance and capacitance. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Role of Nickel Oxide Nanoparticles on Magnetic,Thermal and Temperature Dependent Electrical Conductivity of Novel Poly(vinyl cinnamate) Based Nanocomposites: Applicability of Different Conductivity Models

Nanocomposites of poly(vinyl cinnamate) (PVCin) with various concentration of nickel oxide (NiO) nanoparticles were prepared by in situ polymerization method. The effect of metal oxide particles on the structural, magnetic and thermal stability was analyzed by a high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and thermogravimetric analysis (TGA) measurements. The electrical properties such as room temperature DC conductivity and temperature dependent AC conductivity were investigated with respect to different loading of NiO nanoparticles. XRD and HRTEM images showed the uniform arrangement of nanoparticles inside the macromolecular chain of PVCin. The VSM studies of nanocomposites indicated the hysteresis loops of the ferromagnetic behavior. The saturation of magnetization and coercivity values were varied with the content of NiO nanoparticles. From TGA analysis the composite attain better thermal stability than polyvinyl cinnamate and the thermal stability increases with increase in concentration of nanoparticles. The electrical conductivity of nanocomposite was increased with increase in temperature and also with the loading of nanoparticles. The activation energy values calculated from the AC conductivity was found to be decreases with increase in temperature in all compositions. AC and DC conductivity of nanocomposites were much greater than pure PVCin and the maximum conductivity values were obtained for 10 wt% of composite. Different theoretical equations based on Scarisbrick, McCullough and Bueche model were used to compare the experimentally determined conductivity with theoretical conductivities.