Papers by Keyword: Electrical Conductivity

Abstract: To improve the wear resistance of brass substrate while retaining the electrical conductivity, laser cladding was applied to Cu-WC-Ni composite coating on brass using High Power Diode Laser. Microstructures, phase constitution and wear properties are investigated by means of scanning electronic microscopy with energy disperse spectroscopy and X-ray diffraction, as well as microhardness test and speed friction and wear test. The result shows that microhardness and wear resistance of clad coating were improved obviously compared with the brass substrate owing to the addition of WC ceramic phase, when the content of WC is 25%, the hardness of coating is 4 times of substrate, as well the cumulation mass loss is 1/19 of substrate. Electrical conductivity did not change as copper powder had high electrical conductivity.

Abstract: A vulcanized epoxidized natural rubber (ENR) based electrically conductive compound was successfully prepared by using the combination of internal mechanical mixing and open milling devices. This compound was developed based on a formula with at least 73.0 wt % of petro-chemical free ingredients. The vulcanizate of this compound showed good physical properties, high electrical conductivities and also complied with Malaysia Standard 1097 [. As a result, this newly formulated compound can be targeted for making antistatic tire tread of commercial vehicles.

Abstract: Two containing fluorine functional ionic liquids (ILs) (1-aminoethyl-3-methyl imidazolium trifluoroacetic acid salt ([aemim] [CF₃COO]) and 1-aminoethyl-3-methyl imidazolium trifluoromethane sulfonic acid salt ([aemim] [TfO])) were synthesized and the samples were characterized by means of FTIR, ¹HNMR respectively. The densities, viscosities, and electrical conductivities of the two samples were measured over the temperature range T = (303.15-333.15) K at atmospheric pressure. The solubility of CO₂ in the two samples were investigated at temperature from 303.15 to 333.15 K and pressure from 0 to 7.14 MPa. Results showed that the maximum solubility of CO₂ in [aemim] [TfO] was 0.759 (mole fraction) at 7.01 MPa and 323.15K, and the which of [aemim] [CF₃COO] was 0.646 at 6.49 MPa and 313.15 K. The influence of the temperature and CO₂ partial pressure on the process of CO₂ absorption was discussed. The CO₂ solubilities in different ILs were also compared. The Henry's constants and infinite dilution partial molar volumes for the ILs+ CO₂ systems were obtained.

Abstract: Electrostatic charges are potentially generated on a commercial vehicle through several ways, such as friction of its rubber tyres while rolling on the road and also from the rotating of its mechanical components (e.g. bearings shaft). If these accumulated electrostatic charges are not dissipated from the vehicle, interferences of electronic components within the vehicle may occur. Highly accumulated electrostatic charges may also lead to safety hazards (e.g. fires and explosions) for vehicles that transporting highly flammable materials or during the vehicles refueling process.

Abstract: In this work, polystyrene/ graphene nanocomposite foams were prepared using supercritical carbon dioxide. Chemically reduced graphene oxide were incorporated into PS using latex mixing. Subsequently, the nanocomposites were foamed with supercritical CO2, the foaming temperature is varied. The morphology and electrical properties of the foamed samples were discussed. It is suggested that foaming temperature has significant influence on the morphology of foams. For those samples foamed at higher temperature, foams have thin cell wall and low density even when the content of graphene is relatively high, while they possess good electrical conductivity, may be used as light weight functional materials.

Abstract: Sr, Ca and Fe doped cathode materials Ln_0.7Sr_0.2Ca_0.1Co_0.7Fe_0.3O_2.85 (LnSCCF, Ln=La, Pr and Nd; abbreviated as L-72173, P-72173 and N-72173) were synthesized by microwave sintering (MWS) techniques. The formation process, phase structure and composition were characterized using TG/DTA, XRD and EDS. The thermal expansion behavior of the samples was analyzed in the range of 20-950 °C by thermal dilatometer. The electrical conductivity of the samples was measured with DC four-terminal method from 25 to 900 °C. The X-ray diffraction shows that the samples exhibit a single phase with rhombohedral or cubic perovskite structure after sintered at 1200 °C for 20 min. The electrical conductivity of the samples increases with temperature up to a maximum, and then decreases gradually at higher temperature owing to the creation of oxygen vacancies. The small polaron hopping is regarded as the conducting mechanism (T 550 °C). L-72173 has higher mixed conductivity ( >300 S·cm^-1) in 550-800 °C. The average TECs of L-72173, P-72173 and N-72173 are 1.389× 10^-5 K^-1, 1.417 × 10^-5 K^-1 and 1.416 × 10^-5 K^-1 in the range of 25-800 °C, respectively. They are thermally matched to the GDC better than the YSZ and SDC.

Abstract: The electrical conductivity of network polytetraphenylcalix [resorcinarene (I) and sulfonated polytetraphenylcalix [resorcinarene (II) in the form of Н⁺, Na⁺ , Li⁺, Ag⁺, Ba²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ cations was measured. It was found that the specific conductivity of the polymers in the form of doubly-charged metal cations was 0.2-0.4 S/m. It increased to 1-1.5 S/m when the polymer was in the form of singly-charged metal cations. The specific conductivity of the H-form polymer II became as high as 20 S/m. The self-diffusion coefficients and activation energies of metal cation diffusion in the polymer phase were calculated over the temperature range 298333 K.

Abstract: The nature of doping acid play important role on the stability of conductive polyaniline (PANI). Many recent investigations have focused on different organic acids. Most organic acids are expensive and difficult to synthesize. According to industrial application, it is important to quantify the stability of conductive polyaniline doped with common acids. Herein, three common industrial acids (hydrochloric acid (HCl), sulfuric acid (SA), methanesulfonic acid (MSA)) doped conductive polyaniline was reported. The degradation performance of polyaniline was investigated by XRD and thermogravimetric analysis (TGA). The mechanism of degradation of PANI was discussed. The result indicated that the stability of PANI-HCl was better than that of other two samples. The optimization processing temperature of PANI-HCl is 100°C~150°C.

Abstract: The doping acid will obviously effect on the properties of polyaniline. In order to investigate the industrial acids influence the electrical conductivity stability of polyaniline, the hydrochloric acid (HCl), sulfuric acid (SA) and methanesulfonic acid (MSA) in industrial degree were chosen as doping acids to synthesize polyaniline. The stability of electrical conductivity was measured by in situ temperature. The mechanism of temperature dependence of electrical conductivity was discussed. The results revealed that the stability of polyaniline doped by hydrochloric acid (HCl) was better than that of polyaniline doped by other acids. The variable-range hopping (VRH) model could explain the temperature dependence of electrical conductivity of polyaniline.

Abstract: In this study conductive polymer composites of polyurethane (PU)/polyaniline (PANI) below the percolation threshold were prepared by using solution casting. The dispersion of the conductive PANI fillers within the PU matrix was investigated by scanning electron microscopy (SEM). The SEM results showed a relatively homogeneous dispersion of the PANI fillers within the polymeric matrix. The effects of filler concentration on the dielectric and electrical conductivity depend upon the interface between conductive filler and matrix. Dielectric properties and ac conductivity of polymer composites have been investigated at different frequencies (10² - 10⁵ Hz). The results show that the dielectric constant, dielectric loss and the electrical conductivity are strongly dependent on the frequency. The dielectric constant and dielectric loss decreased, whereas electrical conductivity increased with increasing frequency. In addition, the dielectric constant and conductivity increase when concentration of PANI increased. Differential scanning calorimetry (DSC) presented an enhanced the glass transition temperature (Tg) of the polymer composite with increasing PANI fillers. A correlation of Tg and the interface polarization between the PANI fillers and PU matrix on dielectric properties was proposed.