Formation of conductive pathways in electrolytic copper filled lignocellulose composites

Ispitivana je električna provodljivost sistema baziranog na lignoceluloznom (LC) biopolimernom matriksu ispunjenog elektrohemijski dobijenim bakarnim prahom. Galvanostatski dobijen bakarni prah sa veoma poroznim, veoma dendritičnim i česticama sa velikom specifičnom površinom je korišćen kao punilac. Zapreminski udeo elektrohemijski dobijenog bakarnog praha je iznosio od 2.0 - 29.8 vol%. Analiza najznačajnijih osobina pripremljenih kompozita je obuhvatala merenja električne provodnosti, impedansnu spektroskopiju (IS) i strukturnu analizu. Značajan porast električne provodnosti se javlja kada udeo bakarnog praha dostigne vrednost perkolacionog praga (PP). Pokazano je da PP zavisi od oblika čestica i spatijalne distribucije. SEM analiza uzoraka je pokazala da čestice sa izraženim granicama zrna igraju veliku ulogu u pojavljivanju provodnih puteva i na elektroprovodljivost kompozita. Efekat pakovanja i izraženi međučestični kontantakti između čestica bakarnog praha sa velikom specifičnom površinom su doveli do pomeranja perkolacionog praga, koji za čestice 45 μm i pritisak od 27 MPa iznosi 7.2% v/v.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