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In this communication, we report on the synthesis of vertically aligned aluminium (Al)-doped ZnO (ZnO:Al) nanowire (NW) thin films on FTO-coated glass substrates and their use as photoanode in dye-sensitized solar cells (DSSC). Very thin Al layers (∼3 nm, ∼6 nm and ∼10 nm) were deposited onto chemically synthesized ZnO nanowire film by electron-beam evaporation. The films were then subjected to rapid thermal annealing to incorporate different amounts of Al (∼0.98 at.%, 1.94 at.% and ∼2.89 at.%) into the ZnO nanowires. Optical, microstructural and compositional study of the films confirmed the growth of highly transparent and well-aligned ZnO:Al nanowires with a hexagonal crystal structure. The basic DSSC structure was fabricated using both undoped ZnO nanowire and ZnO:Al nanowire thin films as photoanode. In both cases, commercially available N3 dye was used as a photosensitizer, iodide/tri-iodide solution as electrolyte and FTO-coated glass as counter electrode. A significant increase in short-circuit current was observed, from 1.3 mA cm−2 for the pristine ZnO nanowire film-based DSSC to 4.4 mA cm−2 for the ZnO:Al (2.89 at.%) nanowire film-based DSSC. The overall power conversion efficiency (PCE) was also found to increase from 0.13% (for pristine ZnO nanowire thin film) to 0.49% for the ZnO:Al thin film-based DSSC.

The isothermal crystallization behaviour of the polypropylene (PP) phase in PP/multi-walled carbon nanotubes (MWCNTs) composites has been investigated via differential scanning calorimetric analysis, which showed the influence of the varying dispersion level of MWCNTs in the respective PP matrix. PP/MWCNTs composites were prepared via melt-blending technique, wherein two different grades of MWCNTs of varying average ‘agglomerate’ size and varying entanglements (N-MWCNTs and D-MWCNTs) were utilized. Furthermore, the influence of melt-viscosity of the PP phase was investigated on the crystallization kinetics of the PP/MWCNTs composites. Heterogeneous nucleation ability of MWCNTs has resulted in a decrease in half time of crystallization (t1/2) from ∼14 min for pure PP to ∼6 min for PP/N-MWCNTs and ∼11 min for PP/D-MWCNTs composites at 1 wt% of MWCNTs at 132 °C. Overall rate of crystallization (k) has significantly increased to 4.9 x10−2 min−1 for PP/N-MWCNTs composite as compared with 6.2 x10−3 min−1 for PP/D-MWCNTs composite at 0.5 wt% of MWCNTs at 132 °C. Moreover, the effect of a novel organic modifier, Li-salt of 6-amino hexanoic acid along with a compatibilizer (PP-g-MA) has also been investigated on the crystallization kinetics of the PP phase in PP/MWCNTs composites. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Composites of polypropylene (PP) and multi-walled carbon nanotubes (MWCNTs) were prepared via melt-mixing utilizing Li-salt of 6-amino heaxanoic acid (Li-AHA) modified MWCNTs in the presence of a compatibilizer (polypropylene-g-maleic anhydride; PP-g-MA). Improved interaction between the anhydride group of PP-g-MA and the amine functionality of Li-AHA was confirmed via FTIR and Raman spectroscopic analysis. A higher glass transition temperature (Tg) of the PP phase has been observed in these composites as compared to pristine MWCNTs based composites. The crystallization temperature (Tc) of the PP phase was increased as a function of pristine MWCNTs concentration in PP/MWCNTs composites indicating hetero-nucleating action of MWCNTs. However, Tc value was decreased in the presence of Li-AHA modified MWCNTs indicating the adsorbed Li-AHA on the MWCNTs surface. Moreover, Tc value was higher in the presence of Li-AHA modified MWCNTs with PP-g-MA as compared to that of without PP-g-MA, suggesting the desorbed Li-AHA from the MWCNTs surface due to melt-interfacial reaction. Further, MWCNTs were extracted by hot vacuum filtration technique from PP/MWCNTs composites containing Li-AHA and PP-g-MA. The isothermal crystallization kinetics showed a variation in crystallization behavior of the PP phase in the corresponding composites as compared to the “extracted MWCNTs.” POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Poly (2, 5-benzimidazole) (ABPBI) membrane was prepared via membrane casting method using four different solvents, viz. methane sulfonic acid (MSA), trifluoroacetic acid (TFA), formic acid (FA) and sulfuric acid (SA). Phosphoric acid (PA) was doped in the corresponding ABPBI membrane to enhance the proton conductivity. It has been observed that the ABPBI membrane prepared by different solvents absorbed different amount of PA with varying level of doping, which led to different extent of hardness and Young's modulus as shown via nano indentation analysis. ABPBI membrane prepared using trifluoroacetic acid doped ABPBI membrane (dABPBI-TFA) showed highest proton conductivity of 1.6 x 10(-3) S cm(-1) at 150 degrees C. Fuel cells were fabricated using ABPBI-MSA and ABPBI-TFA based membranes and the performances were evaluated. Current density of 403 and 221 mA/cm(2) was achieved at 0.6 V respectively for the cell based on ABPBI-MSA and ABPBI-TFA membrane when operated at 150 degrees C.

ZnO nanorod structures were deposited on micrometer interdigitated Au electrodes to function as three-dimensional matrixes for the immobilization of antibodies in a capacitive immunosensor format. As a proof of concept, anti-horseradish peroxidase (anti-HRP) antibodies were immobilized on the ZnO nanostructured surface by a crosslinking process. The ZnO nanorod layer allows distribution of antibodies across the entire region probed by the measuring electric field applied to the microelectrodes. This is an alternative approach to the use of more expensive nanometer electrodes necessary in the detection of smaller layers of antibodies. The new micrometer interdigitated capacitive immunosensor was able to discriminate between HRP antigen in buffer; a non-specific antigen in buffer; or buffer alone, as proven by capacitance measurements. Maximum response of the sensor was achieved in the 5–6 kHz frequency range, opening the possibility for a simplified single frequency detection system for direct antigen detection in complex biological samples.

Polyamide6 (PA6)/acrylonitrile butadiene styrene copolymer (ABS) blends with unmodified multiwall carbon nanotubes (MWNTs) were prepared via melt-blending in a conical twin-screw micro-compounder with varying melt-mixing time. To improve the state of dispersion of MWNTs, non-covalent organic modifiers for MWNTs have been utilized: sodium salt of 6-amino hexanoic acid (Na-AHA) and 1-pyrene-carboxaldehyde (PyCHO). PA6/ABS blends with MWNTs have shown a phase morphology transition from matrix-dispersed droplet' type to co-continuous' type as a function of melt-mixing time with the exception of 40/60 PA6/ABS blend with PyCHO-modified MWNTs. Non-isothermal crystallization studies revealed the heterogeneous nucleating action of MWNTs through the presence of double crystallization exothermic peaks (at approximate to 192(degrees)C and >200(degrees)C) while pure PA6 shows bulk crystallization peak at approximate to 192 degrees C. 40/60 and 60/40 (wt/wt) PA6/ABS blends with 5 wt% unmodified MWNTs exhibited electrical conductivity values of approximate to 3.9 x 10(-11) S/cm and approximate to 4.36 x 10(-6) S/cm, respectively. A significant enhancement in electrical conductivity was observed with Na-AHA and PyCHO-modified MWNTs (order of approximate to 10(-6) and approximate to 10(-4) S/cm, respectively). POLYM. ENG. SCI., 55:429-442, 2015. (c) 2014 Society of Plastics Engineers

Multiwall carbon nanotubes (MWNTs) were melt-mixed in polyamide 6 (PA6) and acrylonitrile-butadiene-styrene (ABS) copolymer blends using a simultaneous mixing protocol in order to investigate the state of dispersion of MWNTs in PA6/ABS blends. The blend composition was varied from 40/60 (wt/wt) to 60/40 (wt/wt) in PA6/ABS blends, which showed co-continuous' morphology in the presence of MWNTs. State of dispersion of MWNTs in these blends was assessed through bulk electrical conductivity measurements, morphological analysis, solution experiments, and UV-vis spectroscopic analysis. MWNTs were subsequently modified with a novel organic modifier, sodium salt of 6-aminohexanoic acid (Na-AHA), to improve the state of dispersion of MWNTs. Blends with unmodified MWNTs exhibited the DC electrical conductivity in the range approximate to 10(-11) to approximate to 10(-5) S/cm, whereas blends with Na-AHA-modified MWNTs exhibited DC electrical conductivity in the range approximate to 10(-7) to approximate to 10(-5) S/cm. The reduction in MWNTs agglomerate' size (approximate to 73.7 m for 40/60 blend with unmodified MWNTs to approximate to 59.9 m in the corresponding blend with Na-AHA-modified MWNTs) was observed through morphological analysis. The rheological studies showed increased complex viscosity and storage moduli in lower frequency region in case of blends with Na-AHA-modified MWNTs confirming a refined network-like' structure of MWNTs. POLYM. ENG. SCI., 55:443-456, 2015. (c) 2014 Society of Plastics Engineers

State of dispersion of purified multiwall carbon nanotubes (p-MWNT) in the presence of neutralized MWNT (n-MWNT) in aqueous solution was assessed through UV-Visible spectroscopy, dynamic light scattering measurements, and solution experiments. Raman spectroscopic analysis revealed that debundling of p-MWNT in the presence of n-MWNT in aqueous solution was persistent even in the solid mixture, which was supported by transmission electron microscopic analysis. The proposed mechanism behind the improved dispersion of p-MWNT in the presence of n-MWNT in aqueous solution has been based on the electrostatic charge repulsion between negatively charged n-MWNT. The state of dispersion of p-MWNT in the presence of n-MWNT in 45/55 polypropylene/acrylonitrile butadiene styrene (PP/ABS) blends was assessed through Raman spectroscopic analysis, bulk electrical conductivity measurements, solution experiment, and crystallization studies. Raman spectroscopic analysis indicated that the state of dispersion of MWNT was improved with increasing n-MWNT content of the mixture. This strategy led to a remarkable increase in the bulk electrical conductivity of 45/55 PP/ABS blends at 3 wt% MWNT content and was strongly dependent on the concentration of n-MWNT in the mixture. Differential scanning calorimetric measurements along with solution experiments revealed the subsequent migration of MWNT from the PP phase to the ABS phase in the blends during melt-mixing in the presence of higher fraction of n-MWNT. POLYM. ENG. SCI., 51:1891-1905, 2011. (C) 2011 Society of Plastics Engineers

Cocontinuous blends of 45/55 polypropylene (PP)/acrylonitrile-butadiene-styrene (ABS) with multi-wall carbon nanotubes (MWNT) were prepared by melt-mixing in a conical twin-screw microcompounder. PP-grafted-maleic anhydride (PP-g-MA) and styrene MA were used as compatibilizers for PP/ABS blends. Scanning electron microscopic observations showed phase segregation of PP-g-MA in the blends. State of dispersion of MWNT in the presence or absence of the compatibilizers was assessed through AC electrical conductivity measurements and crystallization studies of the blends. An improvement in AC electrical conductivity was observed in blends in presence of either styrene MA or dual compatibilizers. The lowest electrical percolation threshold was achieved at 0.1 wt % of MWNT using sodium salt of 6-amino hexanoic acid-modified MWNT. Significant increase in crystallization temperature of PP phase of blends with MWNT was observed in the presence of compatibilizers as compared to blends without compatibilizers. An attempt has been made to address the complex issues of phase segregation, compatibilization, and dispersion of MWNT in cocontinuous blends of PP/ABS. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2663-2672, 2011

This article reports the influence of substrate bias during growth and of hydrogen and nitrogen incorporation on density of states [N (EF)] and field-emission threshold (Eturn-on) in tetrahedral amorphous carbon (ta-C) films, deposited using an S-bend filtered cathodic vacuum arc process. The variation in negative substrate bias from −20 to −200 V was found to initially lead to a small decrease in N (EF) and Eturn-on, and a small increase in the emission current density (J) at 12.5 V/μm in the case of as-grown ta-C films; beyond −200 V substrate bias there is a reversal in the trend. The values of N (EF)=1.3×1017 cm−3 eV−1, Eturn-on=8.3 V/μm, and J=6.19 mA/cm2 were observed at −200 V substrate bias. However at −300 V the properties were not very different from those at −200 V substrate bias and so with a view to use the higher energy, hydrogen and nitrogen incorporation studies were carried out in this condition. It was observed that there was further enhancement in properties with hydrogen and nitrogen i...

A simple method is depicted in this communication to determine the optical constants of transparent thin films from transmittance versus wavelength traces, showing no fringes, for evaluating thickness. The strength of this technique is apparent when applied to Zn 1 − x Mg x O films.

Phase morphology of melt-mixed polypro- pylene (PP)/acrylonitrile-butadiene-styrene (ABS) blends was found to be blend ratio dependent, viz., matrix-parti- cle dispersed type of morphology which was observed up to 30 wt % of ABS level beyond which the morphology showed co-continuous type. The domain size of 80/20 PP/ABS blends was found to decrease significantly at 10 wt % carbon black (CB) level, and in case of 70/30 blends morphology was transformed into co-continuous type in the presence of CB, which was retained up to 60 wt % ABS. The finer morphological features were associated with the compatibilizing action of CB particles. Continu- ous network was achieved through aggregated CB par- ticles predominantly in the PP phase wherein one could find CB-rich PP phase and CB-less PP phase. Solution experiments further supported the existence of CB par- ticles preferentially in the PP phase. AC electrical conduc- tivity measurements indicated a 3D network-like structure of CB aggregates in the co-continuous compositions which showed enhanced electrical conductivity as compared to the matrix-dispersed type of morphology in 80/20 PP/ ABS blends which exhibited insulating behavior. On increasing ABS content in the blends the electrical conduc- tivity decreased progressively due to a difficulty in retain- ing 3D continuous network of CB aggregates especially at 40/60 composition. Increased processing temperature led to a higher electrical conductivity in the respective blends. Dielectric measurements revealed the existence of metallic type of conduction in the co-continuous compositions. However, 80/20 blends showed low e 0 value. Overall, structure property relationship studies were conducted in PP/ABS blends with CB. V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 112: 998-1004, 2009

An efficient strategy to achieve electrical conductivity in melt-mixed co-continuous blends is to restrict the conducting filler in a particular phase in the blends next to forming a percolated 'network-like' structure in that particular phase. However, strong inter-tube van der Waals' forces often lead to the aggregated structure leading to higher percolation threshold. In addition, the migration of the conducting filler during melt-mixing and the blending sequence significantly affect the bulk conductivity of the blends. SEM observation showed fine co-continuous structures associated with 50/50 blends of PA6/Surlyn with multiwall carbon nanotubes (MWNT). MWNT were localized in the vicinity of the ionic domains in the ionomer corresponding to a specific blending sequence when unmodified MWNT were used, however, in presence of Na-salt of 6-amino hexanoic acid (Na-AHA) modified MWNT, selective clustering was not observed may be due to the confinement of MWNT in the PA6 phase. To understand these complexities the electrical conductivity of melt-mixed blends of polyamide6/ionomer with MWNT was studied. However, it was observed that the blends with even 3 wt% unmodified MWNT showed insulating behaviour irrespective of the blending sequence adopted. In addition, the key role of a reactive modifier (Na-AHA) in facilitating uniform dispersion and subsequent 'network-like' formation by establishing specific interactions with MWNT was studied. It was found that the MWNT are selectively localized in the PA6 phase in the NA-AHA modified blends manifesting in higher electrical conductivity (∼10 5 S/cm at 3 wt% MWNT) when using a specific blending sequence, due to melt-interfacial reaction between the ∼NH 2 functionality of Na-AHA and the ∼COOH end groups of PA6. FTIR and Raman spectroscopic analysis also supported the existence of the specific interactions.

The application of a sufficiently high negative substrate bias, during the growth of tetrahedral amorphous carbon (ta-C), is usually associated with low sp3 bonding configuration and stressed films. However, in an effort to understand and utilize the higher pseudo thermo dynamical conditions during the film growth, at high negative substrate bias (− 300 V), reported here is a study on ta-C films grown under different hydrogen and nitrogen concentration. As grown ta-C films were studied under different negative substrate bias conditions. The variation of the sp3 content and sp3/sp2 ratio in the ta-C films exhibits a trend similar to those reported in literature, with a subtle variation in this report being the substrate bias voltage, which was observed to be around − 200 V, for obtaining the highest sp3 (80%) bonding and sp3/sp2 (3.95) ratio. The hydrogen and nitrogen incorporated ta-C films studied, at a bias of − 300 V, show an increase in sp3 (87–91%) bonding and sp3/sp2 (7–10) ratio in the range of studies reported. The inference is drawn on the basis of the set of data obtained from measurements carried out using X-ray photoelectron spectroscopy, X-ray induced Auger electron spectroscopy and Raman spectroscopy of as grown and hydrogen and nitrogen incorporated ta-C films deposited using an S bend filtered cathodic vacuum arc system. The study indicates the possibility of further tailoring ta-C film properties and also extending capabilities of the cathodic arc system for developing carbon based films for electronics and tribological applications.

Undoped and doped poly(2,5-benzimidazole) (ABPBI) membrane was prepared by solvent casting method using methane sulfonic acid as a solvent and phosphoric acid (H3PO4) as a doping agent. The concentration of H3PO4 was varied from 0 to 60 vol% to enhance the proton conductivity of the ABPBI membrane at higher temperature. Wide angle X-ray diffraction analysis showed a decrease in crystallinity in ABPBI membrane with increase in H3PO4 doping concentration. The molecular signature and the presence of H3PO4 was observed in 1000–1500 cm−1 in the Fourier transform infrared spectra, which was also supported by a corresponding weight loss at 180°C–200°C in the thermogravimetric analysis. Undoped ABPBI membrane registered the Young's modulus (E) and hardness (H) values of 2.46 and 0.92 GPa, respectively, and the corresponding E and H values for 1.65 doping level of 60 vol% H3PO4 doped ABPBI membrane were 0.14 and 0.067 GPa, respectively. The 60 vol% H3PO4 doped ABPBI membrane with doping level of 1.65 showed highest proton conductivity value of 2.2 × 10−2 S/cm. The impedance spectroscopic analysis and the equivalent circuit model were discussed to understand the nature of proton conduction in H3PO4 doped ABPBI membrane. POLYM. ENG. SCI., 2016. © 2016 Society of Plastics Engineers

Blends of polyamide6 (PA6) and acrylonitrile butadiene styrene (ABS) were prepared in presence or absence of up to 5 wt % of a reactive compatibilizer [styrene maleic anhydride copolymer (SMA) modified with 5 wt % multiwall carbon nanotubes (MWNT)] by melt-mixing using conical twin screw microcompounder where the ABS content was varied from 20 to 50 wt %. The melt viscosity of the blends was significantly enhanced in presence of SMA modified by multiwall carbon nanotubes due to the reactive compatibilization, which leads to stabilized interphase in the blends. Furthermore, the presence of MWNT in the compatibilizer phase led to additional increase in viscosity and storage modulus. Morphological studies revealed the presence of either droplet-dispersed or cocontinuous type depending on the blend compositions. Further, reactive compatibilization led to a significant change in the morphology, namely a structure refining, which was enhanced by MWNT presence as observed from SEM micrographs. DSC crystallization studies indicated a delayed crystallization response of PA6 in presence of ABS presumably due to high melt viscosity of ABS. The crystallization temperature and the degree of crystallinity were strongly dependent on the type of morphology and content of reactive compatibilizer, whereas the presence of MWNT had an additional influence. SAXS studies revealed the formation of thinner and less perfect crystallites of PA6 phase in the blends, which showed cocontinuous morphology. A unique observation of multiple scattering maxima at higher q region has been found in the blends of cocontinuous morphology, which was observed to be successively broadened in presence of the compatibilizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

The 20/80 blends of polyamide 6 (PA6) and acrylonitrile–butadiene–styrene copolymer (ABS) in the presence of styrene–maleic anhydride copolymer (SMA) and multiwall carbon nanotubes (MWNT) were prepared using melt-mixing technique. Crystallization behavior of the PA6 phase in the blends was studied using DSC, WAXD and SAXS techniques. Blends' morphology was characterized by SEM. We observed fractionated crystallization of PA6 phase in 20/80 PA6/ABS blends. It was also observed that the phenomenon of fractionated crystallization was influenced by the presence of both SMA and MWNT. Blends' morphology revealed the presence of wide domain size distribution of PA6 droplets in the amorphous ABS matrix. On incorporation of either SMA or SMA modified MWNT, the average domain size of PA6 droplets was found to be finer up to 1 wt% SMA modified MWNT. Encapsulation of SMA copolymer layer on the MWNT surface was also evident from SEM micrographs. SAXS analysis revealed the formation of multiple lamellae stacking of PA6 phase in the presence or absence of SMA and MWNT in 20/80 PA6/ABS blends. This was attributed to the formation of less perfect crystallites formed during the cooling of melt at higher degree of supercooling., © Elsevier

The study of reflectance and photoluminescence (PL) spectra of as grown and also hydrogen and nitrogen incorporated tetrahedral amorphous carbon (ta-C) films, deposited using an S bend filtered cathodic vacuum arc process is reported here. First the effect of negative substrate bias on the properties of as grown ta-C films and next the effect of varying hydrogen and nitrogen partial pressure at a high substrate bias of − 300 V on the properties of hydrogen and nitrogen incorporated ta-C (ta-C:H and ta-C:N) films are reported for the first time. The values of the optical band gap ( E g ) evaluated using the reflectance spectra were found to decrease with the increase of the substrate bias in the as grown ta-C films. Hydrogen incorporation up to 1.9 × 10 − 2 Pa partial pressure in as grown ta-C films increased the values of E g and beyond which the values of E g decreased while the nitrogen incorporation up to 3.0 × 10 − 1 Pa partial pressure has no effect on the E g values. The PL spectra indicated a strong peak at ∼2.66 eV in as grown ta-C films deposited at − 20 V substrate bias. This main peak was found to shift to higher energy with the increase of the substrate bias up to − 200 V and thereafter the PL peak shifted towards the lower energy. Other peak at 3.135 eV starts appearing and this is found to start shifting to higher energy for films deposited at higher substrate bias. The intensity of the main PL peak was enhanced at low temperature and several other peaks started appearing in place of the broad peak at ∼3.16 eV. The peak width and area of both the main peak were found to decrease with the increase of substrate bias in as grown ta-C films and with the increase of the hydrogen and nitrogen partial pressure used in depositing ta-C:H and ta-C:N films. The current models on the source of luminescence in amorphous carbon have been discussed.

Nanocrystalline GaN films with different crystallite sizes were deposited onto quartz and NaCl substrates by magnetron sputtering of a GaN target in argon plasma. All the films showed predominant hexagonal phase. The band gap values were always found to be higher than that of the bulk. This blue shift in band gap could be attributed to the quantum confinement effect. The optical absorption in these films could be explained by the combined effects of phonon and inhomogeneity broadening along with optical loss due to light scattering at the nanocrystallites. Band edge luminescence is absent in these GaN nanocrystalline films. The line shapes of the photoluminescence (PL) spectra are asymmetric and broad. The film deposited at lower substrate temperature showed broader PL peak. It may be observed that no significant energy shift in the peak positions was observed with reduction in crystallite size but the intensity of the peak decreased for films with the reduction in crystallite size. Below band gap emission observed in this study may also originate due to the presence of polarization-induced electric field present in wurtzite GaN deposited here.

An interfacial reaction during melt mixing of maleic anhydride copolymer (SMA) encapsulated single wall carbon nanotubes (SWNT) and polyamide 6 (PA6) was used in order to disperse SWNT homogeneously and to enhance interfacial adhesion. The intended reactive coupling between PA6 and SMA was evident from IR spectroscopy. Nanocomposites with SMA encapsulated SWNT showed increased elongation at break as compared to PA6/SWNT composites. SEM investigation of tensile fractured surfaces of PA6/SWNT+SMA composites indicated enhanced interfacial adhesion between PA6 and SMA modified SWNT.

Styrene maleic anhydride copolymer (SMA) encapsulated single wall carbon nanotubes (SWNT) were melt mixed with polyamide 6 (PA6) utilizing an interfacial reaction in order to disperse SWNT homogeneously and to enhance interfacial adhesion. The intended reactive coupling between PA6 and SMA was evident from IR spectroscopy. Raman spectroscopy was used to characterize the SWNT and the nanocomposites. Studies on crystallization behavior showed the nucleating behavior of SWNT in the composites, as found using DSC and WAXD. The encapsulation of SWNT by SMA copolymer leads to increased elongation at break in the composites, which can be attributed to the enhanced interfacial adhesion between PA6 and SMA modified SWNT as observed from the SEM investigation of tensile fractured surfaces of PA6/SWNT+SMA composites. The glass transition temperature of PA6 increased significantly in the composites.

In the present investigation, DLC films were grown by saddle-field fast atom beam (FAB) source using acetylene as source gas. The as-deposited films are having properties like low stress (0.1–0.3 GPa), relatively high hardness (9–21 GPa) values and low amount of unbound hydrogen (0.12–2.9 at.%). Stress per unit hardness (SPUH) has been found to be the “figure-of-merit” to describe the film property. A correlation between unbound hydrogen in the DLC films and compressive stress has been established. The effect of nitrogen doping on the properties of DLC films is also investigated. While exploring the conditions for deposition of stress relieved DLC films, many patterns of stress relief behaviour in these films are observed and studied carefully. Surprisingly, we came across new patterns of stress relief behaviour in the case of nitrogen-doped DLC films. This new pattern of the stress relief behaviour, termed as “hexagonal buckling network”, has been found for the first time and claimed here. The detailed observations of this type of stress relief pattern have been presented.

This paper reports the space charge limited conduction (SCLC) and electron paramagnetic resonance (EPR) studies of as grown and nitrogen incorporated tetrahedral amorphous carbon (ta-C) films deposited by pulsed unfiltered cathodic vacuum arc process. The effect of varying substrate bias and nitrogen content on the properties of as grown and nitrogen incorporated ta-C films have been studied. The values of density of states (N(EF)) evaluated from SCLC measurements and spin density (Ns) evaluated from EPR studies of as grown ta-C films deposited at 5 V substrate bias are found to be 1.6×1019 cm−3 eV−1 and 6.7×1019 cm−3, respectively, which decrease to 8.7×1018 cm−3 eV−1 and 4.6×1019 cm−3, respectively, with the increase of substrate bias up to 80 V and beyond 80 V substrate bias these values are found to increase. A small amount of nitrogen incorporation up to 3.6 at.% nitrogen content in nitrogen incorporated ta-C films reduces the values of N(EF) and Ns to 1.4×1019 cm−3 eV−1 and 4.3×1019 cm−3, respectively. Beyond 3.6 at.% nitrogen content, the values of N(EF) and Ns are found to increase monotonically to 2.6×1019 cm−3 eV−1 and 1.0×1020 cm−3, respectively, in nitrogen incorporated ta-C films with further increase of nitrogen content up to 15.6 at.%. The local minimum in the values of N(EF) and Ns in as grown ta-C films deposited at 80 V substrate bias arises due to the ability of sp2 sites to pair up. Nitrogen incorporation up to 3.6 at.% in nitrogen incorporated ta-C films seems to compensate the p-type nature and beyond 3.6 at.% nitrogen content the donor electron increases the values of N(EF) and Ns in the films.

The focus of the paper is to investigate several issues related to the state of dispersion of multiwalled carbon nanotubes (MWNTs) in a polycarbonate (PC) matrix. A masterbatch of PC–MWNT (15 wt.%) was diluted with different amounts of PC in a small scale conical twin screw extruder (DACA Micro Compounder) to obtain different compositions of MWNT. In this system, electrical measurements indicated percolation of MWNT between 1.0 and 1.5 wt.%. We report TEM and AFM investigations of the state of dispersion of MWNT, in the entire volume of the matrix, in selected composites with compositions below (1 wt.% MWNT) and above the percolation threshold (2 and 5 wt.% MWNT). In addition, it was investigated if surface segregation of MWNT and flow induced orientation of nanotubes within the extruded strands had been occurred. It is found that the nanotubes dispersed uniformly through the matrix showing no significant agglomeration in the compositions studied. TEM micrographs seem to be able to detect the percolated structure of the carbon nanotubes. Furthermore, by comparing AFM micrographs from the core region and near to surface region no evidence of segregation or depletion of MWNT at the surface of the extruded strand was found. Comparison of TEM and AFM micrographs on surfaces cut along and perpendicular to the strand direction led to the conclusion that no preferred alignment had occurred as a result of extrusion. Aside from TEM technique, AFM is shown to be suitable to characterize the state of nanotube dispersion along with the issue of surface segregation and orientation of the nanotubes.

Blends were prepared from a high density polyethylene (PE) material and a conductive polycarbonate (PC) composite containing multiwalled carbon nanotubes (MWNT). The PC composite contained 2 wt% MWNT and was prepared by diluting a PC masterbatch consisting of 15 wt% MWNT by melt mixing in an extruder. The aim of blending a conductive PC composite with PE was to obtain a conductive blend at lower amounts of MWNT than required for the pure PC component. The blend morphology was found to be co-continuous over a broad composition range of 30–80 vol.% of the filled PC phase as verified by selective extraction of PC and morphological investigations. The co-continuous structure is very fine with ligaments in the range of 1 μm. Significantly reduced volume resistivity values, i.e. in the range of 10 7 Ω cm, could be achieved in the same composition range of that of the continuous PC phase, i.e. starting at compositions of 30 vol.% filled PC. Here, the total MWNT content in the blend was only 0.41 vol.%. Interestingly, even if the MWNT had been incorporated in the PC phase, the tubes are still visible in the blends after selective extraction of PC. Scanning electron microscopy investigations revealed that the MWNT bridge the PC and PE phases, at least with their ends. This can be understood by the length dimensions of the tubes, which is higher than the phase sizes in the blends.

A correlation has been observed between the residual stress and the optical absorption edge of diamond-like carbon films and on the basis of this correlation, an empirical relation has been established between the Urbach energy ( E 0 ) and the residual stress ( S ) in the films given by E 0 = E 00 + mS , where E 00 =140 meV and m =37 meV/GPa. The residual stress and the optical absorption edges of diamond-like carbon films, grown by different techniques, are then discussed in terms of amount of disorder in the network.

Crystallization behavior of melt-blended polypropylene (PP)/single wall carbon nanotube (SWNT) composites has been studied using optical microscopy and differential scanning calorimetry. Polypropylene containing 0.8 wt% SWNT exhibits faster crystallization rate as compared to pure polypropylene. PP/SWNT fibers have been spun using typical polypropylene melt spinning conditions. The PP crystallite orientation and the SWNT alignment in the fibers have been studied using X-ray diffraction and polarized Raman spectroscopy, respectively.

The compatibilisation of PA6/EVA blends with the addition of an ionomer on the mechanical properties and morphology were studied as a function of ionomer concentration with the primary aim of enhancing the impact strength of PA6 by EVA. The level of EVA was kept at 20%, which formed the dispersed phase, and the ionomer content was varied from 0 to 1.6 wt%. It was found that notched Izod impact strength of PA6/EVA/ionomer blends increased with the incorporation of ionomer to about three times of the value for uncompatibilised PA6/EVA blends. Further, it was observed that on incorporation of the ionomer the tensile strength also increased significantly. Analysis of the tensile data using predictive theories indicated an enhanced interaction of the dispersed phase and the matrix. SEM studies of cryogenically fractured surfaces indicated a decrease in dispersed phase domain size with the addition of the ionomer, while the impact fractured surfaces of PA6/EVA blends indicated extensive deformation with the formation of rumples indicating increased interfacial adhesion as compared to PA6/EVA blends. An attempt has been made to evaluate the compatibilising efficiency of ionomer in PA6/EVA blends. (C) 2002 .

In a novel experiment hydrogenated amorphous silicon films were deposited by modulating the very high frequency (VHF) (100 MHz) discharges, at low frequency (2 Hz) with a nonzero low power level, using pure as well as 25% hydrogen and 25% helium diluted silane as the source gases. During these studies deposition rate is found to depend on the dwell time as in the case of RF pulsed plasma CVD reported earlier by the authors. The films were characterised for optical bandgap, dark and photoconductivity, hydrogen content, microstructure factor, Urbach energy and defect density. The results indicate that, unlike the RF pulsed plasma case, there is an order of magnitude improvement in the photoconductivity of the material due to pulsing the VHF discharges. Urbach energy and defect density studies also indicate an improvement in the film quality. The improvements are more pronounced in diluted silane deposited films. Controlled ion bombardment (of high flux and lower energy) and the resulting ion bombardment induced preparation of the growth surface in the VHF discharges are believed to be the main factors contributing to the observed results. Thus, a more favourable sheath characteristics as obtained during pulsed VHF discharge conditions over RF (13.56 MHz). Silane discharges holds the key to obtain high growth rate deposition of a-Si:H films of acceptable opto-electronic quality xA9; 2002 Elsevier Science B.V. All rights reserved.

The effect of simultaneous addition of multiwall carbon nanotubes (MWNTs) and a reactive compatibilizer (styrene maleic anhydride copolymer, SMA) during melt-mixing on the phase morphology of 80/20 (wt/wt) PA6/ABS blend has been investigated. Morphological analysis through scanning and transmission electron microscopic analysis revealed finer morphology of the blends in presence of SMA + MWNTs. Fourier transform infrared spectroscopic analysis indicated the formation of imide bonds during melt-mixing. Non-isothermal crystallization studies exhibited the presence of a majority faction of MWNTs in the PA6 phase of 80/20 (wt/wt) PA6/ABS blend in presence of SMA + MWNTs. Rheological analysis, dynamic mechanical thermal analysis, and thermogravimetric analysis have demonstrated the compatibilization action of simultaneous addition of a reactive compatibilizer (SMA copolymer) and MWNTs in PA6/ABS blends. An attempt has been made to investigate the role of simultaneous addition of SMA copolymer and MWNTs on the morphology of 80/20 (wt/wt) PA6/ABS blend through various characterization techniques. POLYM. ENG. SCI., 55:457-465, 2015. (c) 2014 Society of Plastics Engineers

Nanocomposite solid polymer electrolytes (SPEs) have been prepared from polyethylene oxide (PEO), organically modified nanoclay (MNclay), and tetraethylammonium tetrafluoroborate (TEABF4) salt. The concentration of the salt has been varied in the respective SPE, wherein PEO/MNclay ratio was kept constant. It has been proposed that three types of complex formation could be operative in the SPEs due to the interactions among PEO, MNclay, and the salt. The complex formation mechanism has been postulated on the basis of X-ray diffraction (XRD) analysis, transmission electron microscopic (TEM) observation, differential scanning calorimetric (DSC) analysis, and polarized optical microscopic (POM) observation. ‘Complex 1’ and ‘complex 3’ formation could be involved in the crystalline phase as indicated by DSC and XRD analyses, whereas ‘complex 2’ formation might be restricted in the amorphous phase as suggested by TEM observation. The ionic conductivity of the SPEs has been correlated with the results obtained from XRD, DSC, and POM analyses. The formation of complex 1 and complex 2 could be responsible for the increase in the ionic conductivity, whereas complex 3 formation might decrease the ionic conductivity. An activated carbon-based supercapacitor has been fabricated using SPEs and characterized by cyclic voltammetry, galvanostatic ‘charge–discharge’ behavior, and impedance spectroscopic analysis. POLYM. ENG. SCI., 55:1536–1545, 2015. © 2015 Society of Plastics Engineers

Poly(p-phenylene benzobisoxazole) (PBO) has been synthesized in the presence of single-wall carbon nanotubes (SWNTs) in poly(phosphoric acid) (PPA) using typical PBO polymerization conditions. PBO and PBO/SWNT lyotropic liquid crystalline solutions in PPA have been spun into fibers using dry-jet wet spinning. The tensile strength of the PBO/SWNT fiber containing 10 wt % SWNTs is about 50% higher than that of the control PBO fibers containing no SWNTs. The structure and morphology of these fibers have been studied.

Reactive compatibilisation of immiscible polymers is becoming increasingly important and a representative study with PA6/EVA system is the focus of this paper. Morphological studies and crystallization behaviour of uncompatibilised and compatibilised blends of PA6/EVA were studied as functions of dispersed phase concentration (EVA or EVA-g-MA) and maleic anhydride (MA) content. Impact properties of the compatibilised PA6/EVA blends were studied as a function of MA content at fixed dispersed phase concentration. SEM studies of cryogenically fractured surfaces showed an increase in average domain size with increase in EVA level. On contrary, the average domain size and the domain size distributions reduced significantly in the presence of EVA-g-MA. This observation is found consistent with increase in EVA-g-MA concentration at a fixed MA level and also at a fixed concentration of dispersed phase with different level of MA in binary and ternary compositions. Morphological observations also revealed that the phenomenon of coalescence is slower in the presence of EVA-g-MA indicating the formation of in situ graft co-polymer at the interface. Impact strength of the compatibilised PA6/EVA blends increased significantly as compared to uncompatibilised PA6/EVA blends. Crystallization studies indicate that PA6 and EVA (or EVA-g-MA) crystallize separately at their bulk crystallization temperature. The degree of crystallinity is reduced marginally with increase in EVA level, whereas, the decrease in crystallinity is more in the presence of EVA-g-MA. SAXS studies indicate the superposition of PA6 and EVA lamellar scattering and the possible mode of insertion is random in nature. In case of reactive systems, SAXS studies also revealed the hindered crystal growth of PA6 and EVA due to the interfacial reaction. (C) 2001 . .

We in this paper report different ways to realise thick diamond-like carbon (DLC) films with stress values lower than 0.5 GPa, Thick DLC films grown by conventional r.f. self bias technique often delaminate from the substrates due to the presence of high compressive stresses of the order of 4–7 GPa. We have made an in-depth study of the delamination problem of DLC films at NPL and found that only for substrates kept away from the plasma (plume) it is possible to grow thick DLC films. This goes to show the heating of the substrates, when m contact with the plasma, appears to be one of the most important factors giving rise to the high stress values. Techniques that have produced consistently low stress values (0.2–0.5 GPa) in this laboratory are pulse plasma PECVD and the one using dc saddle field fast atom beam source. Electronic properties of the materials so produced have been estimated by evaluating Urbach energy using photothermal deflection spectroscopy (PDS) measurements. A correlation between the unbound hydrogen in these films, as measured by a nuclear technique (ERDA), and the stress levels has been found. Deposition rate, room temperature conductivity, optical bandgap and refractive index have also been measured for these films.

A method to filter the diamond-like carbon (DLC) film forming neutral and ionic radicals coming out from a saddle-field fast atom beam (FAB) source is suggested. By flowing different hydrocarbon gases (CH4 and C2H2) through this modified FAB source, DLC films have been grown simultaneously, by beams of neutral and ionic radicals at different locations of the reactor. Current density measurements of these two types of beams confirm the separation of neutral and ionic radicals. Energy distribution analysis of ions shows that the mean energy of the radicals lies within the limit of 50% of the applied voltage to the FAB source. The properties of the deposited DLC films grown by CH4 and C2H2 gases are compared. It is found that DLC films grown by C2H2 gas have higher hardness values than CH4-deposited films. In both the cases, films deposited by neutral radicals have higher hardness values than those deposited by ionic radicals. The values of Urbach energy (E0) evaluated by photothermal deflection spectroscopy (PDS) technique are found to be less in the case of C2H2-deposited films than the CH4-deposited films, but neutral radical-deposited films have higher values of E0 than ionic ones, in both cases.

The influence of melt-mixing parameters on the development of network-like structure of multiwall carbon nanotubes (MWNTs) in injection-molded polypropylene (PP)/MWNTs composites was assessed through AC electrical conductivity measurements. A higher melt-mixing temperature (260 degrees C as compared to 200, 220, and 240 degrees C) at a fixed rotational speed of the screws (150 rpm) and at a fixed mixing time (15 min) has yielded maximum improvement in electrical conductivity in PP/MWNTs composites of 3 wt % MWNTs content. Next to higher melt-mixing temperature, a variation in the melt-mixing time has also led to a variation in electrical conductivity of the composites. Raman spectroscopic analysis revealed an increase in the ratio of intensity due to G-band over that of D-band (IG/ID) of the MWNTs in the skin region as compared to the core region of the injection-molded composites irrespective of the melt-mixing conditions. Microscopic observations could not provide much insight into the variation of MWNTs network-like structure in various PP/MWNTs composites. An attempt has been made to understand the variation of network-like structure of MWNTs in PP/MWNTs composites as a function of melt-mixing parameters through electrical conductivity measurements, Raman spectroscopic analysis, and morphological investigations. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Morphological investigation was carried out with melt-mixed ternary polymer blends of polyamide6 (PA6), polypropylene (PP) and acrylonitrile butadiene styrene copolymer (ABS) in the presence of compatibilizer and multiwall carbon nanotubes (MWNTs). 80/10/10 (wt/wt/wt) PA6/PP/ABS and 80/10/10 (wt/wt/wt) PP/PA6/ABS blends exhibited “core-shell” morphology, whereas 80/10/10 (wt/wt/wt) ABS/PP/PA6 blends exhibited “separately dispersed” phase morphology. The type of phase morphology was unaltered in the presence of either compatibilizer or MWNTs in the respective ternary polymer blends. The morphological refinement in the presence of compatibilizer was explained on the basis of melt-interfacial reaction. In contrast, the refinement in the dispersed droplets in the presence of MWNTs was due to the localization of MWNTs in the specific phase. Dynamic relaxation spectroscopic analysis indicated an increase in the relaxation time of PA6 chain in the presence of compatibilizer in the corresponding ternary blends. The variation in the relaxation time was dependent on the efficiency of the compatibilizer. The variation in the relaxation time for PA6 in the presence of 1 wt% MWNTs in the respective ternary blends also followed a similar trend; however, the extent of mobility of PA6 phase was influenced by the state of dispersion of MWNTs in the corresponding blends. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Growth of amorphous hydrogenated silicon (a-Si:H) films away from so-called standard conditions have recently assumed great importance for extending the range of applications or perhaps even to improve the performance of presently available a-Si:H material. In the present investigation by depositing such films on the cathode of an asymmetric r.f. plasma-enhanced chemical vapour deposition reactor, without any deliberate substrate heating, we could ascertain those conditions where as-grown films show preferentially IR absorption peaks centred around 2000 cm−1. Further, under hydrogen dilution of the feedstock and inducing high self-bias values, by essentially inputting a high r.f. power to the cathode, we find that photoconductivity of the films produced show an order of magnitude change ( σ ph ≈ 10 −6 Ω −1 cm −1 ). A systematic photothermal deflection spectroscopy study has been undertaken to follow the change in a-Si:H film properties through manipulation of the plasma conditions. Implications of the present results are critically examined in the light of other related available information and existing models of growth.

Amine functionalized multiwalled carbon nanotubes (a-MWNT) based polypropylene (PP) composite fibers were prepared in the presence of polypropylene-g-maleic anhydride (PP-g-MA) by melt-mixing followed by melt-spinning with subsequent post-drawing of the as-spun fibers of varying draw ratio (DR). In order to enhance the interfacial interaction, a-MWNT were utilized in combination with PP-g-MA during melt-mixing. Fourier transform infrared spectroscopic analysis revealed the formation of imide bonds between MA functionality of PP-g-MA and amine functional group of a-MWNT. Higher tensile properties of PP/a-MWNT/PP-g-MA composite fibers were registered with varying DR of the as-spun fiber. Orientation factors of a-MWNT and PP chains along the fiber axis were correlated with the higher tensile modulus and tensile strength of PP/a-MWNT/PP-g-MA composite fiber of varying DR. Crystallization studies indicated the role of hetero-nucleating action of a-MWNT in PP/a-MWNT/PP-g-MA composite fiber. POLYM. ENG. SCI., 2012. (C) 2011 Society of Plastics Engineers

Multicomponent polymer blends involving polyamide6 (PA6), polypropylene (PP), acrylonitrile-butadiene-styrene (ABS) and high density polyethylene (HDPE) with multiwall carbon nanotubes (MWNT) were prepared by melt mixing technique to achieve conducting composites. MWNT were either compounded directly or by employing a masterbatch dilution approach in binary (PA6/ABS), ternary (PA6/PP/ABS) and quaternary (PA6/PP/ABS/HDPE) blends. To facilitate "network-like" structure MWNT were pretreated with either sodium salt of 6-aminohexanoic acid or octadecyl tri-phenyl phosponium bromide. Multicomponent blends with pretreated MWNT utilizing masterbatch dilution approach showed significant improvements in the bulk electrical conductivity as compared to blends prepared by direct addition approach at 2 wt % MWNT content. Phase morphology of these blends revealed co-continuous type of morphology wherein MWNT were found to be selectively localized in the PA6 phase. The hetero-nucleating action of MWNT was manifested in increased crystallization temperature of mainly PA6 phase of the blends indicating preferential localization of MWNT in the PA6 phase. POLYM. ENG. SCI., 51:1987-2000, 2011. (C) 2011 Society of Plastics Engineers

Ternary polymer blends of 80/10/10 (wt/wt/wt) polyamide6 (PA6)/polypropylene (PP)/acrylonitrile-butadiene-styrene (ABS), PP/PA6/ABS, and ABS/PP/PA6 were prepared in the presence of multiwalled carbon nanotubes (MWCNTs) by melt-mixing technique to investigate the influence of MWCNTs on the phase morphology, electrical conductivity, and the crystallization behavior of the PP and PA6 phases in the respective blends. Morphological analysis showed the "core-shell"- type morphology in 80/10/10 PA6/PP/ABS and 80/10/10 PP/PA6/ABS blends, which was found to be unaltered in the presence of MWCNTs. However, MWCNTs exhibited "compatibilization-like" action, which was manifested in a reduction of average droplet size of the dispersed phase/s. In contrast, a separately dispersed morphology has been found in the case of 80/10/10 ABS/PP/PA6 blends in which both the phases (PP and PA6) were dispersed separately in the ABS matrix. The electrical percolation threshold for 80/10/10 PA6/PP/ABS and 80/10/10 PP/PA6/ABS ternary polymer blends was found between 3-4 and 2-3 wt% of MWCNTs, respectively, whereas 80/10/10 ABS/PP/PA6 blends showed electrically insulating behavior even at 5 wt% of MWCNTs. Nonisothermal crystallization studies could detect the presence of MWCNTs in the PA6 and the PP phases. POLYM. ENG. SCI., 51: 1550-1563, 2011. (C) 2011 Society of Plastics Engineers

Nano fuller's earth was prepared by milling and subsequent sonication of clay. The polyvinyl alcohol (PVA) and PVA -Nano clay composite films were prepared by solution casting method. The films were characterized for their structural, mechanical, and thermal properties using electron microscopes (SEM, TEM), Tensile Tester, dynamic mechanical analyzer (DMA), thermo gravimetric analyzer (TGA), and Raman spec- troscopy. The nanocomposite films showed improvement in me- chanical properties, viscoelastic behavior as well as resistance towards thermal degradation. Uniform distribution of clay due to intimate interaction between clay and polymer appears to be the cause for improved properties. V C 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3005-3012, 2010

The mechanical and the crystallization behavior of melt-mixed cocontinuous blends of polyamide6 (PA6) and acrylonitrile butadiene styrene were studied in presence of multiwall carbon nanotubes (MWNT). Young's modulus was observed to be significantly improved with increasing concentration of MWNT, while only moderate improvements were observed in the tensile strength. To overcome the van der Waals' forces between MWNT a unique modifier, sodium salt of 6 amino hexanoic acid (Na-AHA) was employed where it was envisaged that specific interactions between Na(+) of the modifier and the delocalized "pi-electron" clouds of MWNT would lead to significant debundiling of the tubes. The mechanical properties of the blends with Na-AHA modified MWNT were found to be improved as compared to the blends with purified MWNT however, were found to be adversely affected above certain concentration of Na-AHA in the blends. Dynamic mechanical thermal analysis supported the plasticization effect induced by Na-AHA manifesting in decrease in the glass transition temperature of PA6 in the blends with Na-AHA modified MWNT. Differential scanning calorimetry results showed two crystallization exotherms for PA6 in the blends with both purified and Na-AHA modified MWNT. This unusual crystallization behavior of PA6 was addressed in context to confined crystallization of PA6 in the tube "network-like" structure. POLYM. ENG. SCI., 49:1533-1543, 2009. (C) 2009 Society of Plastics Engineers

Blends of polypropylene/ethylene octene comonomer (PP/EOC) with conducting fillers viz., carbon black (CB) and multiwall carbon nanotubes (MWNT) were prepared using melt mixing technique with varying filler concentration and blend compositions. Thermo gravimetric analysis studies indicated that presence of filler enhanced the thermal stability of PP/EOC blends. Morphological analysis revealed the formation of matrix-dispersed droplet and co-continuous type of morphology depending on the blend compositions. Significant reduction in droplet size and finer ligament thickness in co-continuous structure were observed in the blends with filler due to compatibilization action. Fillers were found to be aggregated in the EOC phase irrespective of blends compositions and could be related to the affinity of the fillers toward EOC phase. The electrical conductivity of PP/EOC blends with CB and MWNT was found to be highest for 80/20 composition and decreased as EOC content increased. The percolation threshold of CB was between 10 and 15 wt% for the 80/20 and 70/30 blends whereas it was 15-20 wt% for blends with EOC content higher than 30 wt%. The percolation threshold was 2-3 wt% MWNT for PP/EOC blends. This was attributed to the aggregated filler network preferentially in the EOC phase. The melt-rheological behavior of PP/EOC blends was significantly influenced in presence of both the fillers. POLYM. ENG. SCI., 49:1502-1510, 2009. (C) 2009 Society of Plastics Engineers

The constant photocurrent method (CPM) has been used to measure subgap- related parameters such as absorption coefficient α, characteristic energy E 0 of tail states and density of subgap defect states together with an estimate of the band gap of hydrogenated amorphous silicon (a-Si:H) films prepared at various deposition rates. A higher deposition rate in the home-made plasma chemical vapour deposition system was obtained by an improved design of powered electrode and an earthed shield coupled with optimization of process parameters. The results of our measurement show that with increase in deposition rate of a-Si:H films from 6.7 to 18 A s -1 , the values of the characteristic energy E 0 , defect density N s and band gap E g increases from 55.9 to 65.2 meV, from 3.3 × 10 16 to 9.8 × 10 16 cm −3 and from 1.73 to 1.80 eV respectively. CPM measurements were further extended on light-soaked and annealed samples and it was found that E 0 and the defect density increase after light soaking and the effect is reversed after annealing the sample at 160 °C for 1 h.

Multiwalled carbon nanotubes (purified, p-MWNT and ∼ NH2 functionalized, f-MWNT) were melt-mixed with 50/50 cocontinuous blends of polyamide 6 (PA6) and acrylonitrile–butadiene–styrene in a conical twin-screw microcompounder to obtain conductive polymer blends utilizing the conceptual approach of double-percolation. The state of dispersion of the tubes was assessed using AC electrical conductivity measurements and melt-rheology. The rheological and the electrical percolation threshold was observed to be ∼ 1–2 wt % and ∼ 3–4 wt %, respectively, for blends with p-MWNT. In case of blends with f-MWNT, the rheological percolation threshold was observed to be higher (2–3 wt %) than p-MWNT but the electrical percolation threshold remained almost same. However, the absolute values were significantly lower than blends with p-MWNT. In addition, significant refinement in the cocontinuous morphology of the blends with increasing concentration of MWNT was observed in both the cases. Further, an attempt was made to understand the underlying concepts in relation to cocontinuous morphologies that how the geometrical percolation threshold which adversely suffered because of the attrition of tubes under prolonged shear contributed further in retaining the rheological percolation threshold. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1619–1631, 2008