Preparation of graphene-based compounds with improved dispersion by a two-stage production process

Abstract

Abstract Graphene can be used as a functional filler in thermoplastics in order to improve the mechanical and electrical properties, among other things. In the case of high exfoliation and dispersion state, disproportionate increases in compound properties can be achieved even with the lowest filler content. Accordingly, dispersion plays a decisive role here. Up to now, it has not been possible to achieve sufficient dispersion under near-industrial conditions on a twin-screw extruder due to the achievable shear energy input and short residence times. Therefore, this study presents a two-stage compounding process with the aim of improving graphene dispersion. First of all, a predispersion step is carried out in a solvent with the aid of ultrasonic treatment. The predispersed graphene solution is then added to the twin-screw extruder for incorporation. The solvent is removed by a multi-stage degassing process. The results show an improved dispersion compared to conventional addition of the graphene in powder form. In particular, the elongation at break of graphene-based composites can be increased from 13.6% to 57.1% by the increased dispersion.