Electrical Conductivity (electrical + conductivity)

Distribution by Scientific Domains
Distribution within Polymers and Materials Science

Kinds of Electrical Conductivity

  • high electrical conductivity

  • Terms modified by Electrical Conductivity

  • electrical conductivity measurement
  • electrical conductivity value

  • Selected Abstracts


    ELECTRICAL CONDUCTIVITY OF HEATED CORNSTARCH,WATER MIXTURES

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2009
    EDUARDO MORALES-SANCHEZ
    ABSTRACT Electrical conductivity (EC) of cornstarch,water mixtures in the range 10:90 to 70:30 (w/w) was studied as a function of temperature. An external resistive heating system equipped with an electronic device capable of monitoring EC in real time was used and EC of the mixtures was measured while heated at a rate of 5C/min. Results showed that EC went through four different temperature-dependent stages (A, B, C and D). Stage B (41C to 64C) showed a lower EC increasing rate when compared with that of Stage A (from 25C to 41C), probably as a result of starch granule swelling. In Stage C (64C to 78C), EC behavior was found to be dependent on water content. When water content was more than 50%, the value for EC increased. On the other side, EC decreased when water content was less than 50%. Stage C was related to starch gelatinization, according to differential scanning calorimetry results obtained in this study. In Stage D (78C to 92C), a steady increase in EC was observed, probably as a result of the total solubilization of starch in water. It was concluded that Stage C in EC graphs corresponded to cornstarch gelatinization, so it might be possible to use EC monitoring as an alternative technique to measure cornstarch thermal characteristics with different contents of water. PRACTICAL APPLICATIONS Electrical conductivity can be used as an adequate technique to monitor gelatinization, granule swelling and phase change of starch as a function of temperature in corn starch,water mixtures with a wide range of water contents. With this technique, it is also possible to calculate important thermal parameters, such as the beginning and end of the gelatinization and the energy activation for the heating process of cornstarch. This can lead to a better design and control of important industrial corn processes such as alkaline cooking. [source]


    ELECTRICAL CONDUCTIVITY AND KINETIC PARAMETERS OF RICE STARCH

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2007
    E. MORALES SANCHEZ
    ABSTRACT In the present work, rice starch was studied by differential scanning calorimetry (DSC) and electrical conductivity as a function of temperature. The gelatinization temperature was calculated using both methods. Three stages of electrical conductivity were found. When the logarithm of conductivity was plotted versus temperature, the data have been well adjusted to the linear equation, indicating that a model for conductivity may be created using an Arrhenius-type expression to obtain kinetic parameters such as onset, peakset, endset temperatures and gelatinization energy (Eg). The conductivity Eg was calculated and compared to the enthalpy H calculated from the DSC data. It was found that Eg and enthalpy are similar processes. We conclude that electrical conductivity is an alternative method for the study of starch,water mixtures. PRACTICAL APPLICATIONS This research provides a new methodology to obtain kinetic parameters such as temperature of the beginning, medium and ending of gelatinizaiton, which are important for determining the cooking range needed to obtain desired characteristics in a processed starch-containing food. [source]


    THE INFLUENCE of FIELD STRENGTH, SUGAR and SOLID CONTENT ON ELECTRICAL CONDUCTIVITY of STRAWBERRY PRODUCTS

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2003
    I. CASTRO
    ABSTRACT The effects of field strength, soluble solids (from 14 to 59.5 °Brix) and particle size (using two size distributions) on electrical conductivity were investigated. Electrical conductivity increased with temperature for all the products and conditions tested following linear or quadratic relations. Electrical conductivity was found to vary greatly between strawberry-based products. an increase of electrical conductivity with field strength was obvious for fresh strawberries and strawberry jelly but not for strawberry pulp, probably due to the presence of texturizing agents. This parameter decreases with the increase of solids and sugar content. For some of the formulations tested (solid content over 20% w/w and over 40 °Brix) a different design of ohmic heater may be necessary because of the low values of electrical conductivity. [source]


    Electrical Conductivities of (CeO2)1,x(Y2O3)x Thin Films

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002
    Chunyan Tian
    Electrical properties of CeO2 thin films of different Y2O3 dopant concentration as prepared earlier were studied using impedance spectroscopy. The ionic conductivities of the films were found to be dominated by grain boundaries of high conductivity as compared with that of the bulk ceramic of the same dopant concentration sintered at 1500°C. The film grain-boundary conductivities were investigated with regard to grain size, grain-boundary impurity segregation, space charge at grain boundaries, and grain-boundary microstructures. Because of the large grain boundary and surface area in thin films, the impurity concentration is insufficient to form a continuous highly resistive Si-rich glassy phase at grain boundaries, such that the resistivity associated with space-charge layers becomes important. The grain-boundary resistance may originate from oxygen-vacancy-trapping near grain boundaries from space-charge layers. High-resolution transmission electron microscopy coupled with a trans-boundary profile of electron energy loss spectroscopy gives strong credence to the space-charged layers. Since the conductivities of the films were observed to be independent of crystallographic texture, the interface misorientation contribution to the grain-boundary resistance is considered to be negligible with respect to those of the impurity layer and space-charge layers. [source]


    Polyaniline Entrapped in Silver: Structural Properties and Electrical Conductivity

    ADVANCED FUNCTIONAL MATERIALS, Issue 8 2009
    Guy Nesher
    Abstract By employing the new methodology of entrapment of organic molecules within metals, we demonstrate the ability to modify the conductivity of a metal by suitable polymer entrapment. Specifically, polyaniline (PANI) in two molecular weights was entrapped in silver at different concentrations and a comprehensive comparison was preformed for a range of the composite properties, characterized by XRD, SEM, BET, TGA, and density measurements. Pressed films were utilized to measure the electrical conductivity of the composites in order to study the PANI-silver interactions at the molecular level and to establish a correlation between the microscopic morphology and the film conduction. Such correlations have been identified, and are interpreted. This work extends the functional applications of the new metallic composites and offers insight on the polymer-metal molecular level interactions. [source]


    Waterborne, Nanocomposite Pressure-Sensitive Adhesives with High Tack Energy, Optical Transparency, and Electrical Conductivity,

    ADVANCED MATERIALS, Issue 20 2006
    T. Wang
    Transparent and conductive pressure-sensitive adhesives are cast from aqueous colloidal dispersions of poly(butyl acrylate) (P(BuA)) and functionalized carbon nanotubes (CNTs). At the percolation threshold for network formation (at only 0.3,wt,% functionalized CNT), the nanotubes remarkably double the amount of strain at adhesive failure and increase the adhesion energy by 85,% (see figure). The tack properties are explained by current models of adhesive debonding. [source]


    Reversible Photoregulation of the Electrical Conductivity of Spiropyran-Doped Polyaniline for Information Recording and Nondestructive Processing ,

    ADVANCED MATERIALS, Issue 7 2004
    X. Guo
    Reversibly photoswitchable proton transfer processes can occur between a three-state molecular switch based on spiropyran (SP) and the "salt form" of polyaniline (see Figure), both in solution and in the solid state. As a result, the electrical conductivity of the thin-film of SP-doped polyaniline can be photoregulated. [source]


    Electrical Conductivity of Submicrometer Gadolinia-Doped Ceria Sintered at 1000°C Using Precipitation-Synthesized Nanocrystalline Powders

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2008
    Pandurangan Muralidharan
    A simple synthetic strategy has been implemented to obtain low-temperature sintered fine grain size gadolinia-doped ceria, Ce0.9Gd0.1O1.95, (CGO) electrolyte pellets with a high density using weakly agglomerated particles of calcined nanopowders synthesized by a homogeneous precipitation process. The precipitants used were diethylamine (DEA process) and ammonium hydroxide in neutral precipitation (NP process). X-ray diffraction patterns revealed the single-phase crystalline CGO of a fluorite-type structure. The crystalline powder was directly synthesized from solution by the DEA process at room temperature, whereas the NP process powder was crystallized upon hydrothermal treatment at an elevated temperature. Transmission electron microscopy images showed homogeneously dispersed spherical-shaped particles of ,5 nm size for nanopowders calcined at 300°C for 4 h. A high densification range from ,96% to 99% of the theoretical was achieved for the nonconventionally low-temperature sintered pellets at 1000°C from weakly bonded particles of CGO nanopowders calcined at 300°C for 4 h without any sintering aid. The dense CGO pellets sintered at 1000°C for 4 h with an average grain size of ,150,300 nm exhibited a promising high electrical conductivity of 2.03 × 10,2 S/cm (DEA process) and 2.17 × 10,2 S/cm (NP process), measured at 650°C, and low activation energy Ea. The electrical conductivities of fine grain size low-temperature sintered CGO pellets are comparable with the literature reports of sintered pellets using sintering aids, and high-temperature sintered CGO pellets above 1300°C with a larger grain size. [source]


    Effect of Porosity on the Electrical Properties of Polycrystalline Sodium Niobate: I, Electrical Conductivity

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2003
    Silvania Lanfredi
    The electrical behavior of NaNbO3 ceramic samples with different relative densities was investigated by ac impedance spectroscopy in a range of 13 MHz to 10,3 Hz between 400° and 800°C in dry air. Measurements were performed during heating and cooling cycles. The Nyquist impedance diagrams of dense sodium niobate exhibit only one semicircle representing the grain contribution with depression angles as small as 1°, indicating a high homogeneity of the specific electrical properties. In the case of porous samples, the data reveal an additional low-frequency semicircle related to microstructure. For all studied samples, the Arrhenius conductivity plots show a change in the activation energy around 640°C, attributed to the tetragonal-cubic phase transition. The electrical conductivity of porous samples appears to be higher than that of dense ones. [source]


    Electrical Conductivity and Lattice Defects in Nanocrystalline Cerium Oxide Thin Films

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2001
    Toshio Suzuki
    The results of the electrical conductivity and Raman scattering measurements of CeO2 thin films obtained by a polymeric precursor spin-coating technique are presented. The electrical conductivity has been studied as a function of temperature and oxygen activity and correlated with the grain size. When compared with microcrystalline samples, nanocrystalline materials show enhanced electronic conductivity. The transition from extrinsic to intrinsic type of conductivity has been observed as the grain size decreases to <100 nm, which appears to be related to a decrease in the enthalpy of oxygen vacancy formation in CeO2. Raman spectroscopy has been used to analyze the crystalline quality as a function of grain size. A direct comparison has been made between the defect concentration calculated from coherence length and nonstoichiometry determined from electrical measurements. [source]


    Electrical Conductivity of the High-Temperature Proton Conductor BaZr0.9Y0.1O2.95

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2000
    Hans G. Bohn
    The impedance of the cubic perovskite BaZr0.9Y0.1O3-, has been systematically investigated in dry and wet atmospheres at high and low oxygen partial pressures. In the grain interior, conductivity contributions from oxygen ions, electron holes, and protons can be identified. Below 300°C, proton conduction dominates and increases linearly with the frozen-in proton concentration. The proton mobility, with an activation energy of 0.44 ± 0.01 eV is among the highest ever reported for a perovskite-type oxide proton conductor. For dry oxygen atmos-pheres, electron hole conduction dominates with an activation energy of ,0.9 eV. At temperatures <500°C, the grain-boundary conductivity can be separated and increases upon incorporation of protons. The high electrical conductivity and chemical stability make acceptor-doped barium zirconate a good choice for application as a high-temperature proton conductor. [source]


    A Novel Concept for Highly Oriented Carbon Nanotube Composite Tapes or Fibres with High Strength and Electrical Conductivity

    MACROMOLECULAR MATERIALS & ENGINEERING, Issue 11 2009
    Hua Deng
    Abstract A new concept is described for the creation of multifunctional polymer nanocomposite tapes (or fibres) that combines high stiffness and strength with good electrical properties and a low percolation threshold of carbon nanotubes (CNTs). The concept is based on a bicomponent tape (or fibre) construction consisting of a highly oriented polymer core and a conductive polymer composite (CPC) skin based on a polymer with a lower melting temperature than the core, enabling thermal annealing of these skins to improve conductivity through a dynamic percolation process while retaining the properties of the core and hence those of the tape (or fibre). The percolation threshold in the CPC skins of the highly drawn conductive bicomponent tapes could be decreased from 5.3 to 1.1,wt.-% after annealing. [source]


    A diminished capacity for chloride exclusion by grapevine rootstocks following long-term saline irrigation in an inland versus a coastal region of Australia

    AUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2006
    J.M. TREGEAGLE
    Abstract Shiraz and Chardonnay grapevines that had been initially assessed for Cl - exclusion in the 1996 and 1997 harvest seasons at both Merbein (inland region of Victoria) and at Padthaway (sub-coastal region of South Australia), were re-evaluated in 2003 and 2004 at those same two locations. Both scion varieties were grown either on their own roots or were grafted to one of the following rootstocks: Ramsey, 1103 Paulsen, 140 Ruggeri, K51-40, Schwarzmann, 101-14, Rupestris St George and 1202 Couderc. Both sites had been irrigated with saline water since 1994. The salinity of irrigation water at Merbein was approximately 2.1 dS/m; at Padthaway irrigation salinity varied between approximately 1.6 dS/m and 2.5 dS/m during the survey period. Changes in the Cl - -excluding ability of all rootstock/scion combinations between 1996, 1997 and 2003, 2004 were based upon analysis of Cl - concentrations in grape juice and in laminae at harvest, as well as Electrical Conductivity (EC), pH and Sodium Adsorption Ratio (SAR) of the 1:5 soil:water extract. Taking juice Cl - as indicative of rootstock effectiveness for Cl - exclusion, and considering data from Merbein, our analyses demonstrated that overall means for Shiraz juice Cl - increased from around 190 to 427 mg/L over the survey period (7 years). In Chardonnay grapevines at Merbein, overall mean concentrations of Cl - in juice increased from around 70 to around 225 mg/L over 7 years. Significant differences between rootstocks were evident, with some rootstocks at Merbein showing a diminished capacity for Cl - exclusion in 2003 and 2004. By contrast, in Padthaway there was no consistent deterioration in Cl - -excluding capacity by rootstocks supporting either Shiraz or Chardonnay as scions. In 2004 there were significant differences between grapevines at Merbein and Padthaway in the concentration of Cl - accumulated, even though the mean soil EC1:5 after harvest for 0,90 cm depth was the same at both sites, namely 0.4 dS/m. Containment of grapevine salinity at Padthaway (relative to Merbein) between 1996/97 and 2003/04 was most likely due to factors such as a lower volume of saline irrigation, double the rainfall and 27% lower pan evaporation. [source]


    ChemInform Abstract: A One-Dimensional Metal Embedded in Salt Matrices: Synthesis, Modulated Crystal Structures, Electrical Conductivity, and Chemical Bonding of ,1[PdBi6] [(Bi,Sn)1-,Br5- ,,].

    CHEMINFORM, Issue 52 2009
    Bernhard Wahl
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    ChemInform Abstract: AA,2Rh6O12: A New Family of Rhodium Oxides Exhibiting High Thermopower Coupled with High Electrical Conductivity.

    CHEMINFORM, Issue 25 2009
    Hiroshi Mizoguchi
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


    Crystal Chemistry and Electrical Conductivity of Ln2Eu2O3F6 (Ln: Nd, La).

    CHEMINFORM, Issue 20 2006
    Masayuki Takashima
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]


    Facile High-Yield Synthesis of Polyaniline Nanosticks with Intrinsic Stability and Electrical Conductivity

    CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008
    Xin-Gui Li Prof.
    Abstract Chemical oxidative polymerization at 15,°C was used for the simple and productive synthesis of polyaniline (PAN) nanosticks. The effect of polymerization media on the yield, size, stability, and electrical conductivity of the PAN nanosticks was studied by changing the concentration and nature of the acid medium and oxidant and by introducing organic solvent. Molecular and supramolecular structure, size, and size distribution of the PAN nanosticks were characterized by UV/Vis and IR spectroscopy, X-ray diffraction, laser particle-size analysis, and transmission electron microscopy. Introduction of organic solvent is advantageous for enhancing the yield of PAN nanosticks but disadvantageous for formation of PAN nanosticks with small size and high conductivity. The concentration and nature of the acid medium have a major influence on the polymerization yield and conductivity of the nanosized PAN. The average diameter and length of PAN nanosticks produced with 2,M HNO3 and 0.5,M H2SO4 as acid media are about 40 and 300,nm, respectively. The PAN nanosticks obtained in an optimal medium (i.e., 2,M HNO3) exhibit the highest conductivity of 2.23,S,cm,1 and the highest yield of 80.7,%. A mechanism of formation of nanosticks instead of nanoparticles is proposed. Nanocomposite films of the PAN nanosticks with poly(vinyl alcohol) show a low percolation threshold of 0.2,wt,%, at which the film retains almost the same transparency and strength as pure poly(vinyl alcohol) but 262,000 times the conductivity of pure poly(vinyl alcohol) film. The present synthesis of PAN nanosticks requires no external stabilizer and provides a facile and direct route for fabrication of PAN nanosticks with high yield, controllable size, intrinsic self-stability, strong redispersibility, high purity, and optimizable conductivity. [source]


    Electrically Conductive Hydrogen-Bond-Based Supramolecular Polymer with a Tetrathiafulvalene Moiety: Modulation of Electrical Conductivity and Flexibility of Film by External Stimulus

    CHEMISTRY - AN ASIAN JOURNAL, Issue 10 2010
    Seong Jib Choi
    Best supporting role in a film! The 2-deoxyguanosine derivatives having tetrathiafulvalene moieties for a construction of stimuli-responsive supramolecular polymer have been prepared. Owing to a hydrogen-bonding network, the self-supporting film can be fabricated by a simple procedure. The electrical conductivity and flexibility of the film can be modulated by oxidants. The film with TCNQ exhibits electrical conductivity of 3.7×10,2,S,cm,1. [source]


    Preparation, morphology and electrical conductivity of polyaniline/polyoxyalkylene,montmorillonite exfoliated nanocomposites

    POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2008
    N. Salahuddin
    Abstract Polyaniline (PANI)/organoclay exfoliated nanocomposites containing different organoclay contents (14,50,wt%) were prepared. PANI emeraldine base (EB) and oligomeric PANI (o-PANI) were intercalated into montmorillonite (MMT) modified by four types of polyoxyalkylene diamine or triamine (organoclay) using N-methyl pyrolidinone (NMP) as a solvent in the presence of 0.1,M HCl. o-PANI and EB have been synthesized by oxidative polymerization of aniline using ammonium peroxydisulfate (APS). Infrared absorption spectra (IR) confirm the electrostatic interaction between negatively charged surface of MMT and positively charged sites in PANI. X-ray diffraction (XRD) studies disclosed that the d001 spacing between interlamellar surface disappeared at low content of the organoclay. The morphology of these materials was examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Electrical conductivities of the PANI-organoclay and o-PANI-organoclay nanocomposites were 1.5,×,10,3,2,×,10,4 and 9.5,×,10,7,1.8,×,10,9,S/cm, respectively depending on the ratio of PANI. Copyright © 2007 John Wiley & Sons, Ltd. [source]


    Electrical conductivity and crustal structure beneath the central Hellenides around the Gulf of Corinth (Greece) and their relationship with the seismotectonics

    GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 3 2000
    V. N. Pham
    A deep magnetotelluric sounding (MTS) investigation in the western part of the Gulf of Corinth has revealed a complex electrical image of the crustal structure. The geotectonic structure of the Parnassos unit and the Transition zone in the central Hellenides, overthrusting the Pindos zone both towards the west and towards the south, has been clearly identified by its higher resistivity and its intrinsic anisotropy related to the N,S strike of the Hellenides range. Subsequent N,S extension of the Gulf introduced another heterogeneous anisotropy characteristic that corresponds to E,W-trending normal faults on both sides of the Gulf. The 2-D modelling of the MTS results reveals the existence of a relatively conductive layer about 4 km thick at a depth greater than 10 km in the middle crust. It corresponds to a ductile detachment zone suggested by microseismic and seismic studies (King et al. 1985; Rigo et al. 1996; Bernard et al. 1997a). It may be attributed to the phyllite series lying between the allochthonous Hellenic nappes and the autochthonous Plattenkalk basement. Towards the east, under the Pangalos peninsula, approaching the internal Hellenides, the detachment zone could root deeply into the lower crust. Some strong local electrical anomalies are observed, reaching the conductive layer in the middle crust, such as that under the Mamousia fault and under the front of the overthrust of the Transition zone on the Pindos zone. Other anomalies affect only the shallower zones such as that beneath the Helike fault and in the Psaromita peninsula. These shallower anomalies provide complementary information to the study of spatial and temporal variations of the seismic anisotropy in relation to the short- and long-term tectonic activity of the Gulf (Bouin et al. 1996; Gamar et al. 1999). [source]


    Quality of applesauces processed by pulsed electric fields and HTST pasteurisation,

    INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 4 2009
    Z. T. Jin
    Summary A pilot plant scale continuous flow pulsed electric field (PEF) and high temperature short time (HTST) processing system was integrated with an aseptic packaging machine. Fuji applesauce and blueberry applesauce were processed with PEF followed by HTST pasteurisation (PEF + HTST). PEF + HTST processed Fuji applesauce from fresh Fuji apples demonstrated high and stable sensory scores during 9 months storage at 27 °C, and had comparative sensory quality with Meal Read-to-Eat (MRE) and commercial applesauce products stored at 4 °C. PEF + HTST processed blueberry applesauce from pre-pasteurised materials had lower sensory scores than PEF + HTST processed Fuji applesauce and was significantly less stable during the storage at 27 °C. PEF + HTST processed applesauces had aerobic count and mould and yeast count of <10 cfu mL,1 during storage. Electrical conductivity, pH and °Brix, were not significantly changed throughout storage time (P > 0.05). [source]


    Prediction of the effective dielectric constant in SWNT polyimide nanocomposites using the Bruggemann model

    JOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009
    Ricardo PérezArticle first published online: 27 APR 200
    Abstract The Bruggemann model is used in this work to predict the effective dielectric constant of two kinds of single-wall carbon nanotube (SWNT) polyimide nanocomposites. Electrical conductivity and dielectric constant exhibit a dramatic enhancement at low content of SWNT fillers with a percolation threshold at 0.06 vol %. Results of the Bruggemann model are compared with the experimental values of the dielectric constant in CP2/SWNT and ,CN/SWNT polyimide nanocomposites. A reasonable agreement for SWNT contents under the percolation threshold and a SWNT dielectric constant of 2000 was found between the Bruggeman model modified by Giordano and the experimental values. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source]


    ELECTRICAL CONDUCTIVITY OF HEATED CORNSTARCH,WATER MIXTURES

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2009
    EDUARDO MORALES-SANCHEZ
    ABSTRACT Electrical conductivity (EC) of cornstarch,water mixtures in the range 10:90 to 70:30 (w/w) was studied as a function of temperature. An external resistive heating system equipped with an electronic device capable of monitoring EC in real time was used and EC of the mixtures was measured while heated at a rate of 5C/min. Results showed that EC went through four different temperature-dependent stages (A, B, C and D). Stage B (41C to 64C) showed a lower EC increasing rate when compared with that of Stage A (from 25C to 41C), probably as a result of starch granule swelling. In Stage C (64C to 78C), EC behavior was found to be dependent on water content. When water content was more than 50%, the value for EC increased. On the other side, EC decreased when water content was less than 50%. Stage C was related to starch gelatinization, according to differential scanning calorimetry results obtained in this study. In Stage D (78C to 92C), a steady increase in EC was observed, probably as a result of the total solubilization of starch in water. It was concluded that Stage C in EC graphs corresponded to cornstarch gelatinization, so it might be possible to use EC monitoring as an alternative technique to measure cornstarch thermal characteristics with different contents of water. PRACTICAL APPLICATIONS Electrical conductivity can be used as an adequate technique to monitor gelatinization, granule swelling and phase change of starch as a function of temperature in corn starch,water mixtures with a wide range of water contents. With this technique, it is also possible to calculate important thermal parameters, such as the beginning and end of the gelatinization and the energy activation for the heating process of cornstarch. This can lead to a better design and control of important industrial corn processes such as alkaline cooking. [source]


    THE INFLUENCE of FIELD STRENGTH, SUGAR and SOLID CONTENT ON ELECTRICAL CONDUCTIVITY of STRAWBERRY PRODUCTS

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2003
    I. CASTRO
    ABSTRACT The effects of field strength, soluble solids (from 14 to 59.5 °Brix) and particle size (using two size distributions) on electrical conductivity were investigated. Electrical conductivity increased with temperature for all the products and conditions tested following linear or quadratic relations. Electrical conductivity was found to vary greatly between strawberry-based products. an increase of electrical conductivity with field strength was obvious for fresh strawberries and strawberry jelly but not for strawberry pulp, probably due to the presence of texturizing agents. This parameter decreases with the increase of solids and sugar content. For some of the formulations tested (solid content over 20% w/w and over 40 °Brix) a different design of ohmic heater may be necessary because of the low values of electrical conductivity. [source]


    Poly(vinyltriethoxysilane) modified MWCNT/polyimide nanocomposites,Preparation, morphological, mechanical, and electrical properties

    JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2008
    Siu-Ming Yuen
    Abstract Multi-walled carbon nanotube (MWCNT) modified by vinyltriethoxysilane (VTES) via free radical reaction has been prepared (poly (vinyltriethoxysilane) modified MWCNTs, PVTES-MWCNT). Precursor of polyimide, polyamic acid has been synthesized by reacting 4,4,-oxydianiline with 3,3,,4,4,-benzophenone tetracarboxylic dianhydride. PVTES-MWCNT were then mixed with polyamic acid and heated to 300 °C to form CNT/polyimide composite. During the imidization processes, the silanes on CNT surface reacted with each other and may be connected together by covalent bond (SiOSi). The PVTES-MWCNT was analyzed by Fourier transform infrared and X-ray photoelectron spectroscopy. The PVTES-MWCNT/polyimide composites were analyzed by CP/MAS solid state 29Si nuclear magnetic resonance (NMR) spectroscopy. Morphological properties of the PVTES-MWCNT/polyimide composites were investigated by scanning electron microscope and transmission electron microscope. Electrical conductivity increased dramatically comparing to the unmodified MWCNT/polyimide composites. Mechanical properties of nanocomposite were enhanced significantly by PVTES-MWCNT. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 803,816, 2008 [source]


    Electrical Properties of Gadolinium,Europium Zirconate Ceramics

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2010
    Xiao-Liang Xia
    (Gd1,xEux)2Zr2O7 (0,x,1.0) ceramics are prepared via a solid-state reaction process at 1973 K for 10 h in air. (Gd1,xEux)2Zr2O7 (0.2,x,1.0) ceramics exhibit an ordered pyrochlore-type structure; however, Gd2Zr2O7 has a disordered defect fluorite-type structure. Raman spectroscopy analysis indicates that the degree of structural ordering increases with the increase of Eu content. The electrical properties of (Gd1,xEux)2Zr2O7 ceramics are investigated using complex impedance spectroscopy over a frequency range of 0.1 Hz to 20 MHz from 623 to 923 K. Electrical conductivity obeys the Arrhenius equation. Both the activation energy and the preexponential factor for grain conductivity decrease with increasing europium content from Gd2Zr2O7 (x=0) to Eu2Zr2O7 (x=1.0). The measured electrical conductivity of (Gd1,xEux)2Zr2O7 ceramics increases with increasing Eu content and temperature. Electrical conductivity of the pyrochlore-type materials is higher than that of the defect fluorite-type material in (Gd1,xEux)2Zr2O7 solid solution systems. The electrical conductivity of (Gd0.4Eu0.6)2Zr2O7 is almost independent of oxygen partial pressure from 1.0 × 10,4 to 1.0 atm. The high ionic transference number of (Gd0.4Eu0.6)2Zr2O7 ceramic at different temperatures proves that conduction is purely ionic with negligible electronic contribution. [source]


    Electrically Conducting Gels Formed From Polyaniline/Ethylcellulose/m -Cresol Ternary Solutions

    MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 10 2004
    Ignacio González
    Abstract Summary: Polyaniline doped with camphorsulfonic acid (PANI-CSA) and ethylcellulose (EC), constitutes the basis of the investigated binary PANI(CSA)0.5/m -cresol and ternary PANI(CSA)0.5/EC/m -cresol solutions. Ternary solutions give rise to gels with a lower elastic modulus and electrical conductivity than binary PANI(CSA)0.5/m -cresol gels. However, the dimensional stability is considerably improved, since warping observed in binary gels is eliminated or lessened. These results are explained considering the role played by ethylcellulose, which interacts with the hydroxyl group of m -cresol, skimping PANI(CSA)0.5/m -cresol specific interactions and retarding solvent evaporation. Electrical conductivity of binary (,) and ternary (,) gels as a function of m -cresol content. The arrow indicates that warping is observed below this solvent level. [source]


    Influence of Stabilizer Concentration on Transport Behavior and Thermopower of CNT-Filled Latex-Based Composites

    MACROMOLECULAR MATERIALS & ENGINEERING, Issue 5 2010
    Yeon Seok Kim
    Abstract The influence of the stabilizer/SWNT ratio on the transport behavior of latex-based polymer nanocomposites is examined in an effort to improve electrical conductivity while maintaining or improving the Seebeck coefficient (i.e., thermopower). Results show that phonon and electron transport are significantly affected by tube/tube junctions, and the carrier transport across the junctions can be manipulated by altering the stabilizer concentration. Electrical conductivity of composites containing 10,wt.-% SWNT nearly doubles, becoming greater than 900,S,·,m,1, by changing the SWNT:GA ratio from 1:3 to 10:1, while thermal conductivity and Seebeck coefficient remain relatively constant (near 0.25,W,·,m-K,1 and 40,µV,·,K,1, respectively). [source]


    Electrical conductivity of vanadium dioxide switching channel

    PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 9 2010
    A. Pergament
    Abstract The electrical conductivity of the switching channel of vanadium dioxide thin-film sandwich structures is studied over a wide temperature range (15,300,K). It is shown that the electrical resistance of the channel varies with temperature as R,,,exp(aT,,,b/T) in the high-temperature region (above 70,K). The experimental results are discussed from the viewpoint of the small polaron hopping conduction theory which takes into account the influence of thermal lattice vibrations onto the resonance integral. [source]


    Electrical conductivity and optical properties of poly(3-thiophene boronic acid) organic semiconductor

    POLYMER ENGINEERING & SCIENCE, Issue 4 2009
    Fahrettin Yakuphanoglu
    Electrical conductivity and optical properties of the poly(3-thiophene boronic acid) have been investigated. The room temperature electrical conductivity and activation energy of the poly(3-thiophene boronic acid) were 2.0 × 10,9 S/cm and 0.17 eV, respectively. In the semiconductor region of the polymer, the charge transport mechanism is taking place by the hopping process in the localized states. The direct optical band gap value of the poly(3-thiophene boronic acid) was found to be 1.92 eV via optical absorption method. The width of localized states for the polymer was determined to be 0.36 eV. The refractive index dispersion curve of the polymer obeys the single oscillator model. The refractive index dispersion parameter Eo/So for the poly(3-thiophene boronic acid) was determined to be 9.82 × 1012 eV m2. The optical dielectric constants of the polymer were determined. The real part of the dielectric constant of the polymer is higher than that of imaginary part of the dielectric constant. The imaginary part shows a peak corresponding to the absorption edge. It is evaluated that the electrical and optical results of the poly(3-thiophene boronic acid) indicate that it is an organic semiconductor with electrical and optical parameters. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers [source]