REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

FORMATION OF THE CONDUCTIVE PATHWAYS AND ELECTRICAL CONDUCTIVITY OF THE COPPER FILLED LIGNOCELLULOSE COMPOSITES

MIROSLAV M. PAVLOVIĆ

University of Belgrade, ICTM-CMM, 11000 Belgrade, Serbia, mpavlovic@tmf.bg.ac.rs

VLADAN ĆOSOVIĆ

University of Belgrade, ICTM-CMM, 11000 Belgrade, Serbia

MILADIN GLIGORIĆ

University of East Sarajevo, Faculty of Technology, Zvornik, Republic of Srpska, BiH

VASO BOJANIĆ

University of Banja Luka, Agrifaculty, Banja Luka, Republic of Srpska, BiH

MIOMIR G. PAVLOVIĆ

University of East Sarajevo, Faculty of Technology, Zvornik, Republic of Srpska, BiH

Abstract: The electrical conductivity of the composite system based on lignocellulose (LC) biopolymer matrix electrodeposited copper powder filler has been studied. Highly porous, highly dendritic galvanostatically produced copper powder was used as filler since these particles have high values of specific area. Volume fraction of the electrodeposited copper powder was varied from 1.9 - 29.4 vol%. Analysis of the most significant properties of prepared composites and its components included impedance spectroscopy (IS) behavior, measurements of electrical conductivity, scanning electron microscopy (SEM) and structural analysis. The significant increase of the electrical conductivity could be observed as the copper powder content reaches the percolation threshold (PT). It was shown that PT depends on both particle shape and type of spatial distribution. IS measurements and SEM analysis have shown that particles having pronounced grain boundaries have great effect on appearance of electric conductive pathways thus on the composite conductivity. The packaging effect and more pronounced interpartical contact with copper powder particles lead to “movement” of PT, which for the particles <45 μm and highest processing pressure of 27 MPa was 7.2% (v/v). IS response of the composites showed existence of electrical conductive layers, each having different resistivity which increases towards interior of the composite.

Keywords: electrolytic copper powder, impedance spectroscopy, lignocellulose, composite.