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In this work, Additive Manufacturing by Material Extrusion (AM-ME) was applied for the manufacture of a material based on a corn storage protein, zein, which is a by-product of starch production.

During the process, the molten material is extruded as a filament deposited layer by layer. Cohesion between layers requires the spreading of the extruded filament and the interdiffusion of polymers in the contact areas between the layers. For this purpose, the study of the fusion-bonding properties of this protein was carried out. Zein, plasticized by glycerol, is extruded as cylindrical filaments. An experimental device, based on the AM-ME process, was set up to monitor the fusion-bonding of zein-based filaments placed in an instrumented oven. The evolution of the fusion-bonding front was followed by image acquisition and analysis.

We were able to determine the optimal conditions (zein/glycerol amount, temperatures, time) that allow us to obtain filaments presenting properties close to those of standard synthetic materials (ABS, for example). Extruded zein-based filaments showed efficient fusion-bonding behavior and can thus be considered for the 3D printing of edible or bioresorbable parts with targeted porosity, in order to control the release of active ingredients in the formulation of pharmaceutical products.