###### Abstract
It would be thus highly desirable to substitute or at least to partially replace silica with an alternative filler, maintaining the same composite dynamic mechanical properties and eliminating or at least reducing the mentioned drawbacks. The alternative filler should have functional groups able to establish a chemical bond with the elastomer chains and/or to create a hybrid network with silica. The hybrid network should promote less filler networking than silica and, as a consequence, should favor lower compound viscosity. A lower acidity, with respect to silica, is also desirable to have more efficient vulcanization. The objective of this work was the partial replacement of silica with a nanosized sp\({}^{2}\) carbon allotrope. Nanosized graphite with a high surface area and high shape anisotropy (HSAG) [6] was chosen. The nano size was selected to have a high interfacial area with the polymer matrix and, thus, great efficiency at low filler content. The carbon allotrope was selected as it was expected to substantially reduce the abovementioned drawbacks arising from silica: indeed, it has lower surface activity and acidity. Papers on rubber composites with graphene and related materials (GRM), mainly based on isoprene rubber, are available in the scientific literature [7; 8; 9; 10; 11; 12]. The main objective of these researchers was to achieve an ultimate distribution and dispersion of the GRM. The main outcome of the papers is the rational design of the surface chemistry of the filler [10]. In most cases, latex dispersions were prepared with polar graphitic materials, such as graphene oxide, known as GO [7; 8; 10; 11; 13; 14; 15; 16; 17; 18]. HSAG is characterized by a low number of stacked layers, in a crystalline domain, and by a high crystalline order inside a single basal plane. Studies performed by the authors on HSAG have been reported elsewhere [19; 20; 21; 22; 23; 24; 25; 26]. In order to promote the compatibility with silica and the reactivity with the elastomer chains (through a coupling agent), HSAG was functionalized with OH groups (HSAG-OH). A reaction was performed between HSAG and a pyrrole compound, serinol pyrrole (SP). Some of the authors reported that a pyrrole compound, such as SP, is able to react with the edges of graphene layers [19; 20; 21; 22; 23; 24; 25; 26]. The functionalization reaction is characterized by a high atom efficiency and occurs through a domino mechanism [26]: the pyrrole compound undergoes a carbocatalyzed oxidation in the benzylic position and gives rise to a cycloaddition reaction with the carbon substrate. The OH groups could also be reactive with the silane (e.g., TESPT), and thus, they could promote the chemical bond with the elastomer. HSAG-OH was characterized, determining the thermal stability and the amount of the organic modifier. The efficiency of the functionalization reaction was estimated. Elastomer composites based on poly(styrene-co-butadiene) rubber from anionic solution polymerization (S-SBR) and poly(1,4-cis-isoprene) from _Heeva brasiliensis_ (natural rubber, NR) were prepared. Silica was used as the filler. A minor amount of silica, 15% by volume, was replaced with either HSAG or HSAG-OH, maintaining the same volume fraction of the filler. Crosslinking was performed with a sulphur-based system. Tensile properties were studied through quasistatic measurements. Dynamic mechanical properties were measured both in the shear and in the axial mode. Some of the authors have shown that nanocarbon allotropes, such HSAG and CNTs, in particular, give rise to elastomer composite materials whose properties are directly dependent on the used carbon allotrope. The anisotropic mechanical behavior of the systems was investigated by means of DMAtests, performed on specimens taken from plates in shear-sandwich configuration. The rheological properties were studied by measuring the Mooney viscosity and by means of high pressure capillary viscosimeter (HKV) tests.