Growing interest in developing sustainable materials that reduce dependence on fossil resources has led to increased development of bio-based elastomers that can compete with traditional materials in terms of performance when reinforced with additives. This study shows that functionalizing graphene oxide with different alkylamine chains (C8, C12, and C16) enables precise, multidimensional modulation of polymyrcene rubber (PMy) composite behavior. The main finding is that there is a critical concentration of ~1.5–2.0 phr and an optimal chain length of C16 that maximizes mechanical strength, elongation, and toughness simultaneously, thus avoiding the classic trade-off between stiffness and extensibility. Additionally, the study reveals biphasic behavior of graphene oxide modified with dodecylamine (GO_A12) on curing kinetics. At low concentrations, GO_A12 slows vulcanization by competing with accelerators, while at higher concentrations, it accelerates vulcanization via Zn–amine–sulfur complexes. This duality is reflected consistently in the crosslink density, Payne effect, and tensile properties, establishing a coherent structure–property correlation. Identifying an optimal crosslinking regime of ~8.5 × 10⁻⁴ mol/cm³ as the common denominator of the best formulations provides a rational design guide for high-performance elastomers based on renewable matrices and graphene-derived reinforcements. The decrease in tan δ observed through mechanical dynamic analysis suggests potential applications in the tire industry due to increased energy dissipation, which would improve fuel efficiency.

The conversion of industrial carbon wastes into functionalized graphene materials represents an attractive strategy for the sustainable production of advanced carbon nanomaterials. In this work, a graphitized coke-like waste generated during metallurgical coke production was evaluated as a precursor for the preparation of graphene oxide (GO) and amine-functionalized graphene oxide, using a commercial synthetic graphite as a reference material. Prior to oxidation, both graphites were subjected to a mild aqueous liquid-phase exfoliation (LPE) treatment employing water as the sole processing medium. Graphene oxides were subsequently prepared using a modified Hummers method and functionalized with n-octylamine through an ultrasound-assisted reaction. X-ray diffraction confirmed the successful conversion of both graphitic precursors into graphene oxide through the appearance of the characteristic (001) reflection at approximately 10–11° (2θ). Structural characterization revealed that the LPE treatment promoted partial delamination of the graphitic crystallites while preserving graphitic crystallinity. FTIR and thermogravimetric analyses indicated that LPE modified the distribution and accessibility of oxygen-containing functionalities generated during oxidation. After amination, the LPE-derived materials exhibited more pronounced spectroscopic and thermal changes, suggesting a greater participation of reactive oxygen-containing groups during functionalization. The results demonstrate that graphitized coke waste can be transformed into graphene oxide and nitrogen-functionalized graphene materials with characteristics comparable to those obtained from commercial graphite, providing a simple and sustainable route for the valorization of industrial carbon residues into value-added graphene-based material.