Chemical modification of starch in order to get thermoplastic properties

Abstract: There are numerous advantages of replacing traditional non-biodegradable synthetic plastics with bio-based plastics. Starch is globally available, cheap, renewable, and biodegradable. However, starch has a poor product performance and is relatively difficult to process, as conventional melt processing techniques cannot be used. By introducing thermoplastic properties to starch, the mechanical properties and processability can be enhanced. The aim of the project was to modify starch and give it thermoplastic properties. The implementation of this included various experiments, where aromatic, cyclic and aliphatic side groups were added to the biopolymer. The effect of the different side groups provided valuable insight into how the material properties changed. Subsequently, the thermoplastic properties of the modified starch were analyzed by different analytical methods, including Fourier-transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). In conclusion, the TGA showed lower thermal stability in the functionalized starch compared to native starch. Some indications of thermoplastic behavior were observed from the DSC. Trade-off between functionality and thermostability needs to be overlooked when aiming to increase thermoplastic behavior and future work should explore TEMPO oxidation, to obtain better results from the TGA.