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Electrically conductive composites of poly(urea‐formaldehyde) and cellulose filled with aluminum
Author(s) -
Pinto Gabriel,
Maaroufi AbdelKarim
Publication year - 2012
Publication title -
polymer composites
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.577
H-Index - 82
eISSN - 1548-0569
pISSN - 0272-8397
DOI - 10.1002/pc.22361
Subject(s) - materials science , composite material , percolation threshold , volume fraction , thermosetting polymer , porosity , composite number , electrical resistivity and conductivity , percolation (cognitive psychology) , conductivity , homogeneity (statistics) , chemistry , statistics , mathematics , neuroscience , electrical engineering , biology , engineering
Abstract This article addresses the preparation and characterization of composite materials obtained with compression molding of mixtures of aluminum powder and a commercial grade thermosetting resin of poly(urea‐formaldehyde) filled with α‐cellulose in powder form. The homogeneity of these composites was checked by the morphologies of the constituents (filler and matrix) by optical microscopy. The density of the composites was measured and compared with values calculated by assuming different void levels within the samples, to discuss the porosity effect, in connection with optical microscopy observations. Then, the dependence of electrical conductivity of the composites on volume fraction of the metal filler was investigated. The conductivity of the composites is <10 −12 S/cm unless the metal content reaches the percolation threshold at a volume fraction of V c = 38.6 vol%, beyond which the conductivity increases markedly by as much as nine orders of magnitude, indicating an insulator–conductor phase transition. The obtained results on electrical conductivity have been well interpreted with the statistical percolation theory. The deduced critical parameters, such as the threshold of percolation, V c , the critical exponent, t , and the packing density coefficient, F , were in good accord with earlier studies. In addition, the hardness of samples remained almost constant with the increase of metal concentration. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers