Development and characterization of thermoplastic zein biopolymers plasticized with glycerol suitable for injection molding

Resumen

This research focuses on the development of high environmentally efficiency materials based on zein plasticized with glycerol, processed through extrusion and injection molding techniques. The work addresses the study of the influence of glycerol content on the processability of thermoplastic zein (TPZ), as well as its effect on mechanical and thermomechanical properties, thermal transitions, degradation, microstructure, zein-plasticizer interactions, surface appearance, and wettability. The incorporation of glycerol facilitates the processing of thermoplastic zein. To process these materials through extrusion and injection molding, a minimum amount of 15 wt% glycerol is required, while formulations with more than 40 wt% glycerol expel part of the plasticizer through exudation. Through these processing techniques, it is possible to obtain thermoplastic zein with a tensile strength of up to 27.9 MPa, and elongation at break between 5 % and 6 %. The glass transition temperature, Tg, is significantly reduced from 43 ºC to values around 37 ºC, demonstrating the plasticizing efficiency that glycerol can exert on zein. This work demonstrates the feasibility of extrusion and injection molding processes for obtaining glycerol-plasticized thermoplastic zein (TPZ), expanding the possibilities of zein use as a potential substitute of some petroleum-derived commodity plastics.