Thermoplastic Starch (TPS) Obtained from Mango Kernel Flour by Means of Extrusion Process with Different Plasticizers

This work reports on the development of thermoplastic starch materials based on mango kernel flour. Mango kernel has a high starch content, which is why the flour obtained after grinding can be used as raw material to obtain thermoplastic starch (TPS) or rather starch rich thermoplastic materials. For this purpose, a plasticization process is carried out in a twin-screw extruder using different plasticizers, namely glycerol, sorbitol and urea, which are thereafter subjected to an injection-moulding process to obtain tensile test samples. In order to assess the difference in properties depending on the plasticizer used, the rheological, mechanical and morphological properties were characterized and evaluated. Sorbitol and urea plasticized thermoplastic starch showed superior mechanical properties to those of the sample with glycerol, achieving tensile strengths close to 3 MPa and an elongation at break of 50%. This was ascribed to the higher molecular weight of sorbitol and the higher amount of active functionalities in urea and sorbitol, which allow to form stronger bonds with starch during thermoplastification. Morphological images confirmed this fact and showed that MKF particles were also present in the TPS matrix, probably acting as reinforcing agents that enhance the mechanical performance of the materials.