Effect of melt‐processing conditions on the electrical conductivity and microwave absorbing properties of composites based on clean scrap poly(vinylidene fluoride/ethylene vinyl acetate copolymer and graphene nanoplatelets

Abstract Clean scrap polyvinylidene fluoride (rPVDF) from industrial reject was compounded with ethylene vinyl acetate (EVA) copolymer and graphene nanoplatelets (GNP) to produce low cost and scalable conductive composites. The effect of the melt processing conditions (temperature, time, and rotor speed) on the electrical conductivity and microwave absorbing (MWA) properties was investigated. All systems presented co‐continuous morphology indicated by scanning electron microscopy (SEM) and selective extraction experiments. The preferential localization of GNP in the EVA phase was evidenced by selective extraction and thermogravimetric analysis (TGA). Higher conductivity value was observed for the composite processed at 210°C for 3 min at a rotor speed of 200 rpm. The MWA performance of monolayer and bilayer composite structures with 2 mm thickness was investigated in terms of minimum reflection loss (RL) and effective absorption bandwidth (EAB). The bilayer system provided the best MWA response with RL = − 43.1 dB (>99.99% of EM attenuation) when prepared at 190°C for 3 min at a rotor speed of 200 rpm. The ecological and environmental importance of finding new applications for plastic waste, and the low cost of the materials and processing make this composite an interesting candidate for MWA purpose. Highlights Promising application of clean scrap polyvinylidene fluoride (PVDF) in microwave absorbing materials; Conductivity and absorbing performance are affected by processing conditions; Co‐continuous structure of rPVDF/EVA blend influenced by graphene nanoplatelets (GNP); Selective localization of GNP in EVA phase; Outstanding microwave absorption properties achieved with bi‐layer structure.