Wheat (Triticum) is an annual cereal grain plant in the grassy family, constituting almost 50% of the total grain harvest in Sweden. Within the Vinnova Competence Centre: FibRe, we are devoted to turning wheat straw biomass into thermoformable materials with as little modification as possible. The aim is to gain in-depth understanding of how to create a lignocellulosic fibre feedstock from straw and further make the material thermoformable, based on the unique spatial and compositional structure of the straw tissue. A systematic methodology has been applied for extracting lignocellulosic feedstock from wheat straw in a mild yet efficient process that preserves wheat straw’s cellulose fiber integrity, while minimizing lignin content. Straw has been pulped following a hydrothermal soda treatment. Systematic variations of process parameters were made according to a five-level and three-factor central composite design (CCD). Response surface modeling (RSM) revealed factor-response relationships and synergic effects between time, temperature, and NaOH concentration on the lignocellulosic yield and composition. From these data, the optimal conditions can be predicted regarding yield, lignin content and cellulose content .
Different chemical paths for bringing thermoplastic properties to the wheat pulp fibers have been investigated within the project. However, the heterogeneity of the feedstock presents a challenge to determine at which level the modifications occur. Here, the polymerization of acrylates and itaconates on fibres’ surface is discussed to provide thermoformability and processability to the material. The modified fibers were characterized by FT-IR, TGA, DSC and SEM. Materials have been prepared by hot-pressing and extruding the modified fibers to simulate an application for the packaging industry.