Material extrusion of plant biopolymers: Opportunities & challenges for 3D printing

The current applications of 3D printing by Material Extrusion (ME) to biopolymers other than polylactic acid (PLA) are scarce. The present paper reflects on the benefits and challenges of using plant biopolymers in for ME. The challenges are considered on the basis of (1) a review of additive manufacturing (AM) techniques applicable to biopolymers, (2) the current material specifications required to comply with the ME processing window, and (3) modeling and optimizing the process. In parallel, the potential benefits are discussed in terms of new fields of application (such as food and biomedical) and related reverse engineering possibilities. In both cases, an edible plant protein (zein from maize) is considered as an example. It is used to illustrate the formulation challenges for ME processability, focusing on the role of plasticizers. Finally, a reverse engineering approach is presented that combines algorithms for generating structures and deterministic finite element modeling. This enables the design of ME printable parts with a targeted structure and final properties such as controlled release during mastication for biomedical applications.