Conducting polymer composites of zinc‐filled urea–formaldehyde

Abstract

This article is concerned with the preparation and characterization of composite materials prepared by the compression molding of mixtures of zinc powder and urea-formaldehyde embedded in cellulose powder. The morphologies of the constituent, filler, and matrix were investigated by optical microscopy. The elaborated composites were characterized by density, which was compared with calculated values, and the porosity rate was deduced. Further, the hardness of samples remained almost constant with increasing metal concentration. The electrical conductivity of the composites was less than 10 Ϫ11 S/cm unless the metal content reached the percolation threshold at a volume fraction of 18.9%, beyond which the conductivity increased markedly, by as much as eight orders of magnitude. The obtained results interpreted well with the statistical percolation theory. The deduced critical parameters, such as the threshold of percolation, the critical exponent t, and the packing density coefficient were in good accord with earlier studies.

Non‐linear electrical conductivity of urea‐formaldehyde‐cellulose loaded with powders of different carbon fillers

“…(3)) was tested in our case without success. Equation (4), on the other hand, was used with success in earlier similar studies to interpret the experimental results, 26,28,29,31 and it provides a good result here. Therefore, the fit, above the percolation threshold of electrical conductivity, as a function of volume fraction of fillers is given in Figure 10.…”

“…The electrical conductivity was determined from the resistance values that were measured using a twopoint arrangement as described elsewhere. 26,29 Three specimens of each composition were tested, taking four data points on each sample. To decrease the contact resistance, the sample surfaces were coated with silver paint.…”

The effect of filler morphology on thermal characteristics of lignocellulose and metal powders composites

“…U literaturi se poslednjih godina mogu naći brojne informacije o mogućnostima primene polimera koji sadrže dispergovane provodne punioce, kao i različite metode za proizvodnju takvih materijala [5][6][7][8][9][10][11][12]. Termosetovi sa jednokomponentnim epoksidima su izrazito povoljni za dobijanje blendi polimera *Autor za korespondenciju: Miroslav Pavlović E-mail:mpavlovic@tmf.bg.ac.rs Rad primljen: 21.…”

Recent Progress in Kinetics of Thermal Degradation Mechanisms in Polymer Composites

“…They may either be insulating or conducting, though both of them are equally useful. Insulating composites are applicable as thermal greases, thermal interface materials, and electric cable insulations, while conductive composites are exploited in thermo electrical and thermo mechanical applications, and organic electronics [1,[2][3][4][5][6]. However, in order to continue satisfying the global demands (particularly of energy), there are certain issues which need to be addressed regarding the polymer composites [7].…”