The study demonstrates how the pep interactions between two
seemingly incompatible filler materials e lignin and carbon black e
can be used to create novel hybrid filler particles for rubber compounds.
The study shows that the surface characteristics and the
morphology of the hybrid particles can be controlled by the ratio of
the two materials in the hybrid filler. It is seen that both kraft lignin
and lignosulfonate molecules are capable of forming coating layers
on CB particle aggregates and that the coating layers maintain the
fractal nature of CB particles. Raman spectroscopy analysis and
solid state NMR confirmed that the interactions between lignin and
CB occur due to p stacking over length scales of several nanometers.
These results are further confirmed by zeta potential
measurements.
The hybridization of lignin and carbon black is shown to be
advantageous on a number of accounts. First, it alleviates the
concerns associated with the detrimental effects of large particle
size of lignin on mechanical properties of rubber compounds;
the hybridization process renders lignin as coatings on CB particles
and that lignin does not appear as separate particles in
rubber compounds. Second, the process subdues networking of
carbon black in rubber compounds by the dual action of lignin
coating layers and the filling of the space between carbon black
primary particles; both these effects make the hybrid particle
aggregates stiffer. Accordingly, the hybrid particles do not undergo
as much flocculation as CB. This is reflected in the lowering
of loss tangent values of rubber compounds of hybrid fillers for
rubber networks of a given crosslink density. The study provides
data in support of partial replacement (up to 10 wt%) of CB in
rubber formulations with bio-derived, energy efficient, and less