## 4 Conclusions  
This work reports a simple and sustainable way of improving the ultimate and fracture properties of a nanocomposite based on natural rubber and a graphitic material. The nanocomposite is characterized by the ultimate dispersion of a nanosized high surface area graphite, achieved by modifying the chemical nature of the carbon allotrope, thus without using an extra amount of mechanical energy. The polarity of HSAG was increased, thanks to functionalization with serinol pyrrole; a masterbatch of HSAG-SP in NR was prepared by coagulating the HSAG-SP dispersion in NR latex. The functionalization with the pyrrole compound, with respect to the traditional approach based on GO, has the following main features: it does not require a reduction step (either thermal or chemical) and the use of hazardous chemicals and harsh reaction conditions, and it leaves the bulk structure of the graphitic substrate substantially unaltered. The polar HSAG-SP does not act as GO, as a crosslinking agent for the polymer chains, but promotes the ultimate dispersion of the graphene layers. Composites, with either pristine HSAG or HSAG-SP, were then prepared with melt blending, using traditional equipment and energy. Good dispersion of the graphene layers appears to be responsible for better ultimate and fracture properties of the sulphur-crosslinked HSAG-SP composites. These results were obtained by using HSAG with a low amount of SP and by preparing the dispersion of HSAG-SP in water and then in NR latex by means of magnetic stirring. Recent studies [34; 91] have demonstrated that the shear rate of order of magnitude of \(10^{4}\) s\({}^{-1}\) can lead to extensive exfoliation of the graphitic aggregates and that the affinity of graphite for the solvent (obtained through functionalization) is highly beneficial. The perspective of the present research proceeds by obtaining a larger exfoliation of graphitic adducts with SP by using appropriate technology, also in view of a scale up, which appears feasible. Through tailor-made functionalization of the graphitic material, with the appropriate pyrrole compound, composites based on different elastomers will be prepared, with evenly dispersed graphene layers and hybrid filler systems, aimed at reproducing the improvements of the properties shown in the present work.  
Conceptualization, M.G., S.A. and G.P.; methodology, M.G., S.A.; formal analysis, G.P., S.A. and W.B.; investigation, G.P., S.A., W.B. and L.C.; resources, M.G., S.A., L.C. and B.S.; data curation, G.P., S.A. and W.B.; writing--original draft preparation, M.G., G.P., S.A., L.C., W.B. and B.S.; writing--review and editing, M.G., G.P.; supervision, M.G., B.S.; project administration, M.G. All authors have read and agreed to the published version of the manuscript.  
This research was funded under two of the projects (grant number: 854178, grant number: 21647053) by the Austrian Research Promotion Agency (FFG).  
Pirelli Tyre S.p.A. is gratefully acknowledged for supporting the PhD activity of [PERSON]. Part of this research work was performed at the Polymer Competence Center Loebn GmbH (PCCL, Austria) and within the COMET-modul \"Polymers4 Hydrogen\" within the framework of the COMET-program of the Federal Ministry for Transport, Innovation and Technology and Federal Ministry for Economy, Family and Youth, with contributions by the Department of Polymer Engineering and Science (Montanuniversitaet Leoben). The PCCL is funded by the Austrian Government and the State Governments of Styria, Lower Austria and Upper Austria.  
The authors declare no conflict of interest.