Towards tough and strong thermoplastic polymer blends: exploring the morphology, mechanical reinforcement, and dielectric properties of PA-6/COPE/Graphene nanocomposites

A Nylon 6 (PA-6)/copolyester elastomer (COPE) 85/15 wt. % blend was reinforced with carboxyl-functionalized graphene nanoplatelets (GnP). GnP was prepared using the modified Hummers–Offeman method, and nanocomposites containing 0–1.25 wt. % GnP were prepared by twin-screw melt extrusion followed by injection moulding. GnP enhanced interfacial interaction at low loading with the PA-6 matrix. At 1 wt. % GnP, tensile and flexural moduli increased by approximately 39% and 42%, respectively, compared with the PA-6/COPE blend, while toughness and Izod impact strength increased by approximately 32% and 14.5%, respectively. The glass transition temperature increased from 40°C to 71°C, indicating restricted chain mobility and improved thermo-mechanical stability. Dynamic modulus at −25°C and ambient temperature increased by approximately 32% and 102%, respectively, while the loss modulus showed a marked change in the low-temperature region. Degree of crystallinity increased from 17.90% for the PA-6/COPE blend to 20.20% at 1.25 wt. % GnP, accompanied by increased crystallization temperature, consistent with a heterogeneous nucleating effect. Stiffness-related properties continued to increase up to 1.25 wt. % GnP, whereas 1 wt. % GnP provided the best overall balance of strength, toughness, impact resistance, thermo-mechanical performance, dielectric response, and morphology. Enhanced complex permittivity and dielectric loss indicate potential for future EMI shielding applications.