Steady state viscosity and dynamic viscoelastic properties for the suspensions of carbon black at various surface treating stages were measured using cone and plate type rheometer. The surface modification of carbon black was performed by silane coupling agents. The relations between the degree of modification and rheological properties of the suspensions were mainly discussed by considering the alteration of flocculated network structure formed by dispersed particles.
With increasing surface treating level of the particles, the apparent viscosity of the suspension decreases and shear thinning behavior is gradually diminished. The values of storage modulus decrease and the frequency dependence of them increases with surface treating. These phenomena are associated with the reducing of aggregated structures formed by dispersed particles. With proceeding the surface treating by silane coupling agent phenyl group covers the particle surface to prevent the inter-particle aggregation and fills in the nano-pore on the particle surface. Consequently, flocculated network structure is gradually reduced and the specific surface area is also reduced with increasing surface treating agent. However excess silane coupling causes inter-particle bonding and structural formation and consequently the relation between surface treating time and viscoelastic behavior becomes vague.
View full abstract