Viscoelastic behavior of carbon black and its relationship with the aggregate size

The viscoelastic behavior of binderless carbon black compacts under dynamic compression (0.2–10.0 Hz, static strain 1.0–2.5%, deformation amplitude 9.4–16 lm and packing density 0.18–0.45 g/cm) is governed by the solid part of the compact, with the elastic character dominating the viscous character. The viscous character increases with increasing aggregate size, while the elastic character decreases. The interparticle movement in an aggregate contributes to the viscous deformation, while the connectivity among the aggregates contributes to the stiffness. The loss tangent of the solid part increases with increasing aggregate size up to 300 nm, which is optimum for viscoelasticity. A larger specific surface area weakly correlates with a lower storage/loss modulus of the solid part. The particle size does not correlate with the viscoelastic behavior. Both viscous and elastic characters increase with increasing static strain, due to the tightening of the solid part. The loss tangent of the solid part is up to 1.2, compared to 21 and 0.67 for exfoliated graphite and rubber respectively. The storage and loss moduli of the solid part (up to 21 and 180 kPa respectively) are below those of rubber, but are above or comparable to those of exfoliated graphite. Possible applications relate to mechanical isolation. 2013 Elsevier Ltd. All rights reserved.