sp2 carbon allotropes are efficient reinforcing fillers for polymer melt and
elastomers: carbon black (CB) has been used since early 1900’s and nanofillers such
as carbon nanotubes (CNT), graphene and graphene related materials (GRM) have
increased their importance over the last decades. Nanofillers can definitely
establish larger interfacial area with the polymer matrix than CB and great impact
on material properties is thus expected. However, it is widely acknowledged that
they will not be able to completely replace CB. Hence, increasing research efforts
are on hybrid systems based on CB-CNT and CB-GRM [1]. Research objective is to
identify common features and behaviour of nano (CNT, GRM) and nanostructured
(CB) sp2 carbon allotropes.
In this work, initial modulus was determined by means of dynamic-mechanical
shear measurements of composites based on either poly(1,4-cis-isoprene) or
poly(styrene-co-butadiene) as the rubber and either CB or CNT or GRM or hybrid
systems as the reinforcing fillers.
Filler-polymer interfacial area (i.a.), calculated as the product of filler surface
area, density and volume fraction, was used to establish a common correlation
with the composite initial modulus. A sort of master curve was derived, able to fit
all the points up to interfacial area of about 27 μm-1, corresponding to remarkable
filler content.
Much better efficiency was shown by carbon fillers, when composites were
prepared through latex blending. To allow easy dispersion in rubber latex, sp2
carbon allotropes were functionalized with a serinol derivative: 2-(2,5-dimethyl-
1H-pyrrol-1-yl)-1,3-propanediol (serinol pyrrole, SP) [2, 3], shown in Figure 1
