Segregated Networks of Carbon Black in Poly(vinyl acetate) Latex: Influence of Clay on the 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.