GrafCoat - Graphene based extrusion coating for paperboard

Purpose and goal:

Thermoplastic biopolymer-graphene composites that could be hot-pressed into thin films were developed in the project (Goal 1). The water vapor barrier (WVTR) of the biopolymer (thermo plastic starch, TPS) was substantially improved (Goal 2). The initial plan also included adhesion studies of the films to paperboard (Goal 3).

This was not conducted as time was allocated to fulfill Goal 1. Also, a selection of a suitable composition of the composite for pilot trials was planned (Goal 4) but the project did not reach this far. Expected results and effects:

Biopolymers (starch and nanocellulose) were used to disperse graphene in water and enhancing the compatibility with the hydrophilic biopolymer matrix (TPS). TPS-graphene composites were produced by mixing the dispersions with TPS powder and plasticizer followed by evaporation of the water. By optimizing mixing time and conditions composites of the right thermoplastic properties were obtained, allowing the material to be hot-pressed into thin and larger area films. The barrier properties (WVTR) were improved by the graphene addition, at the most by 98%.

Approach and implementation:

Holmen and 2D fab supplied RISE with nanocellulose and graphene, respectively. RISE dispersed the graphene in water with nanocellulose or starch, according to previously developed protocols. RISE blended the composites, hot-pressed them into films and evaluated barrier properties. Holmen performed extractive studies on the films, solvent extraction (acetone) and volatile emission at 100°C.