Thermoplasticization of starch using ionic liquids

Supervisors: Eric Leroy &  Denis Lourdin

 

Abstract

The development of biobased thermoplastic starch materials requires exploring new paths. The path studied in this work is comprised of using ionic liquids as a new family of plasticizers that can modify the transformation of starch during extrusion and the final properties of the resulting material. Unlike classic plasticizers, ionic liquids grant a large variety of properties by tuning the structure of their consisting anions and cations. On the other hand, the latest develoments show that the characterization and the comprehension of the influence of regular starch plasticizers, glycerol for one, was done through a long process, and many questions have yet to be answered. That’s why we chose to proceed with a three-step experimental study:

As a first step, around ten ionic liquids were synthesized by combining the biocompatible cholinium cation with biodegradable anions. A screening of their plasticizing properties on starch was then conducted.

The second step consists of a detailed study on the impact of the chosen ionic liquids on the thermoplasticization mechanism, rheology in the molten state and the properties of the plasticized starch; in particular on re-crystallization and glass transition. Significant differences were noted compared to glycerol.

Lastly, we studied a novel functional property of ionic liquids, they allow biopolymer blends compatibilization, including starch/zein blends.