Specific Volume Resistivity Research Articles

CHARACTERISTICS OF ELECTRICALLY CONDUCTING POLYMER-COATED TEXTILES

Intrinsically conducting polymer (ICP)/textile composites were prepared by coating polypyrrole (PPy) or poly (3,4-ethylenedioxythiopene) (PEDOT) on the fabrics through chemical and electrochemical oxidation of pyrrole or EDOT. We investigated the effects of the preparation conditions on the properties of the resulting composite such as ICP content, electrical conductivity, surface morphology, and electromagnetic interference shielding effectiveness (EMI SE). The specific volume resistivity of the composite was as low as 0.3 Ω-cm, giving rise to about 36 dB of EMI SE over the wide range of frequency up to 1.5 GHz. We also prepared the elastic textile composites, exhibiting a monotonic increase of the electrical resistance with the elongation up to 50%. We, therefore, propose the elastic textile composite can be used as a strain sensor for large deformation.

PET fabric/polypyrrole composite with high electrical conductivity for EMI shielding

Polypyrrole (PPy) was polymerized chemically and electrochemically in sequence on a polyester (PET) woven fabric, giving rise to PET fabric/PPy composite with high electrical conductivity. In the chemical polymerization, pyrrole dissolved in an aqueous solution without or with polyvinyl alcohol as a surfactant was first sprayed on the PET fabric and oxidized by spraying an aqueous solution of an oxidant and a dopant. Electrochemical polymerization was carried out in an aqueous electrolyte solution by applying a constant current density to the PET fabric coated with chemically polymerized PPy and a stainless steel plate as the working and the counter electrodes, respectively. We investigated the effects of the chemical or the electrochemical polymerization conditions on the properties of the resulting composite such as surface morphology, electrical conductivity, environmental stability, and electromagnetic interference shielding effectiveness (EMI SE). We found that the composite shielded EMI by absorption as well as reflection and that EMI shielding through reflection increased with the electrical conductivity. The specific volume resistivity of the composite prepared in this study was extremely low as 0.2 Ω cm and EMI SE was in the practically useful range of about 36 dB over a wide frequency range up to 1.5 GHz.

Electrically Conducting Polymer Blends with Thermally Processable Polyaniline

Thermally processable polyaniline (PANI) was synthesized by one-step chemical oxidation of aniline, whose electrical conductivity was in the range of 10−2 to 1 S/cm. Various kinds of thermoplastic polymers were thermally blended with the processable PANI, giving rise to the electrically conducting polymer blends with the specific volume resistivity of 102 to 1010 Ω-cm.

Diffusion of Stable Radicals and Electric Current in Polymeric Composites

Abstract Influence of stable iminoxide radicals on the conductivity of several filled by carbon black polymers has been investigated. It has been shown that sorbtion—desorbtion of stable radicals correlates with the change of specific volume resistance ρ, of these materials. This effect is due to capture of charges by radicals localized in the polymer matrix near conductive channels.

New cloth from basalt fibres

The possibility of production of basalt and glass—basalt cloth for electrical insulation and construction applications was demonstrated. The technological production parameters were developed and the physicomechanical indexes of the cloth were determined. It was found that the specific volume electrical resistance of basalt and glass—basalt fabrics is one order of magnitude higher than the specific volume electrical resistance of glass cloth.

Irradiation change of the specific volume resistivity of magnesium-filled polymer compositions on the base of LDPE

Abstract Examined are metal-filled polymer compositions on the base of low density polyethylene (LDPE) with a differing content of magnesium (10, 20, 30 and 40%). After irradiation with gamma rays (60Co) of a well-defined dose a transition from high to low resistivity is observed for the 30 and 40% Mg composites. The radiation-induced change of specific volume resistivity permits the development of conducting polymer materials on the base of metal-filled composites with a wide range of application in engineering.

Abnormalities in electrical and acoustic properties of thermoplastic polyurethane

The temperature dependence of ultrasonic pulse velocity C and specific volume resistance ρv of crystallizing thermoplastic polyurethane (TPUR) was investigated. It was revealed that under certain conditions TPUR acquired abnormally low ρv values and C values uncharacteristic of polymers. An explanation for the observed abnormalities could be based on the assumption of the presence of ‘hot’ electrons in TPUR.

Polyimides from diamines and dianhydrides

AbstractNovel polyimides have been synthesized by reacting 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride with three diamines having the general structure: magnified imagePolyimide films obtained have been evaluated for their thermal and electrical properties. The dependence of the thermal stability of the polyimides on the structure of the diamine component has been established. The specific volume resistivity has been found to be of the order of 1015 Ω cm for all the polyimides.

Effect of the structure of electrically conducting polymer compositions on their properties. Review

This literature survey covers research on the properties of systems consisting of a polymeric binder and an electrically conducting filler. The conditions are discussed, under which structure is developed in these compositions, in which the specific volume resistance is reduced suddenly by several orders of magnitude and the system becomes capable of carrying an electric current. Theoretical considerations and experimental evidence relating to possible mechanisms of conduction in these systems are discussed.

The effect of gamma-neutron radiation on the electrical conductivity and dipole segmental relaxation of polystyrene

The specific volume resistance ϱ ν , the dielectric and the gel fraction of polystyrene irradiated in a nuclear reactor have been investigated. It was found that dependence of ϱ ν and tan δ maximum on radiation dosage is represented by curves containing extrema. It was found that the constant characterizing the increase in ϱ ν over the dosage range of ∼40–810 Mrad is greater than the value usually obtained for β-irradiation. Some reduction in the relaxation time distribution parameter was noted at 17 and 200 Mrad and the reduction was greater at 806 Mrad.