3.5 Effect of ultrasonication on plasticizer incorporation into lignocellulose matrix

Polymeric materials are essential in today’s modern society but they also have their disadvantages like often being fossil-based and difficult to recycle or degrade. Cellulose is an abundant biopolymer already widely used, while also being bio-degradable and recyclable. The downside is that cellulose materials are not thermo-processable like most conventional thermoplastics. Our approach, inspired by plasticization of gluten1, is to incorporate a small amount of plasticizer into the lignocellulose matrix. Our hypothesis is that the small plasticizing molecules will reduce the strong intermolecular interactions within cellulose and enhance the molecular mobility. Successful implementation will increase the lignocellulose’s thermo-processability and yield a material which can be processed through conventional thermo-processing such as extrusion. A step on the way has been the incorporation of different bio-based plasticizers through ultrasonication as a mean to open up the fibres, aiding the sorption of glycerol, urea and citric acid. The solution is thereafter filtrated to form sheets that are dried at elevated temperature. The formed materials have been evaluated in regard to plasticizer content, thermal behaviour, degree of crystallinity and interaction with water. In this work, the primary focus was to understand the effect of ultrasonication on plasticizer adsorption and its correlation to the highly improved physical properties of the formed sheets.