Segregated networks of carbon black in poly(vinyl acetate) latex: Influence of clay on electrical and mechanical behavior

Films were prepared from mixtures of PVAc latex, CB, and natural sodium montmorillonite clay. In the absence of clay, these composites exhibit a percolation threshold of 1.2 vol.-% CB, which is nearly an order of magnitude lower than that observed for composites prepared using PVAc solution. SEM images reveal a segregated CB network that is the result of excluded volume created by the much larger polymer particles in the latex. With the addition of 0.2 wt.-% clay, the
percolation threshold is reduced to 0.9 vol.-% carbon black due to clay-induced networking. The storage modulus is also enhanced by the presence of clay, although higher clay concentration appears to adversely affect electrical and mechanical behavior of these composites.