Effect of Carbon Black on the Morphology, Mechanical Properties and Electrical Conductivity of Porous Composites based on Natural Polymers

This study investigates the effect of carbon black (CB) in structural, conductive and mechanical properties of highly porous composite materials based on chitosan and cellulose diacetate (CDA) obtained by lyophilization. It has been established that the structure of materials strongly depends on the polymer-solvent system. So, composites chitosan /CB have a lamellar structure, while CDA/CB have a lattice structure. Using BET and SEM methods, it was shown that the addition of a large number of CB particles leads to the formation of dendriform type branches and displacement of filler agglomerates outside the walls, which leads to an increase in the specific surface area (SSA) and a decrease in porosity. A difference in the apparent elastic modulus of composites has been established; the maximum values are reached at a concentration of 9 wt % (chitosan/CB) and 38 wt % (CDA/CB). When studying the conductive properties, it was found that composites exhibit the classical “conductor-insulator” behavior, and analysis using the two-exponential phenomenological percolation equation (TEPPE) showed that the systems CDA/CB have a percolation threshold below (13 vol %) and higher conductivity than chitosan/CB (32 vol %). This fact is due to polymer-filler interactions that affect the process of freezing and dispersion of CB, and hence the structure and functional properties of materials. Thus, the use of different polymer matrices with the addition of the same filler leads to the production of composite materials that differ in their characteristics.