Structuring and electric conductivity of polymer composites pyrolysed at high temperatures

Abstract

On the basis of mixes of phenolformaldehide and epoxy resins at the presence of some silicon organic compounds and fiber glasses annealed in vacuum and hydrogen media the new conductive monolithic materials have been created. Conductive, magnetic and some other properties of these materials were investigated. It was established experimentally that the obtained products are characterized by semiconductive properties, the level of conductivity and conductive type of which are regulated by selection of technological methods. The density and mobility of carriers increase at increasing of annealing temperature up to definite levels. The temperature dependence of the electrical conductivity and charge mobility were described by Mott formulas. The magnetic properties of the annealed materials were investigated by ESR method. It was established that at annealing free radicals and other paramagnetic centers are formed. On the basis of the obtained results it was proposed that formation of conducting clusters and the charge transport between them is provided by mechanism of charge jumping with alternative longevity of the jump.

Gradiently Anisotropic Conducting and Magnetic Polymer Composites

“…4 shows that the maximum heights of the local resistances depend on the value of stretching. This result is in good agreement with the known conception on the mechanism of conductive polymer composites conductivity [3]. Investigation of obtained films using the metallographic microscope shows that the average optical density of penetrated light through the film nearly exponentially depends on the ordinates of the elementary squares.…”

“…If the polymer is filled with different dispersive fillers, particularly with electric conductive and magnetic materials (graphite, carbon black, metal powders), the particles distribution of the latter ones interacting with macromolecules transforms from the chaotic state to the orientation one. The change of polymer microstructure significantly defines the material electric and magnetic properties [3,4].…”

Polymer Composites on the Basis of Epoxy Resin with Mineral Fillers Modified by Tetraetoxysilane

“…Therefore the attention of the scientists is attracted to substances which would eliminate the mentioned leaks. It is known that silicon organic substances (both low and high molecular) display hydrophobic properties, high elasticity and durability in a wide range of fillings and temperatures [6,7].…”

Organic semiconductors for device applications: current trends and future prospects

“…The additive concentration at which this transition occurs is termed as the "percolation threshold" when the electrical conductivity sharply increases by several orders of magnitude due to the formation of continuous electron conducting pathways. Prior to this transition, electron pathways are not there and the matrix material dominates the electrical properties while above the transition, and multiple electron pathways facilitate conduction, which finally ends up in saturation [191,197,198].…”

“…In conventional conducting additives, micron-sized metal/carbonaceous materials, such as carbon black (CB), exfoliated graphite, and carbon fibers were used in high concentrations from 10 to 50 wt% [191,[197][198][199][200], resulting in poor mechanical strength. In contrast to these, the blending of CNTs into polymer minimized such problems by forming conducting pathways in the insulating polymer by converting them into conducting composites at very low additive concentrations.…”