A review of 3D and 4D printing of natural fibre biocomposites. (September 2020) - Le Duigou, Antoine
Abstract: To date, the literature has focused on synthetic fibre-reinforced composites, but it has not adequately addressed the unique properties that differentiate natural from synthetic fibres, such as their natural variation in microstructure and composition across species. This review paper proposes a critical overview of the current state of 3D printing of natural fibre-reinforced composites or biocomposites for mechanical purposes, as well as an overview of their role in 4D printing for stimuli-responsive applications. The paper is structured as follows: after the first part recalling the specificities of natural fibres and their associated composites, the two main sections are each divided into two parts presenting an analysis of the available data to provide fundamental understandings and a discussion and outlook for the future. Natural discontinuous fibre-reinforced polymers exhibit moderate mechanical properties compared to composites manufactured by conventional processes due to specific factors of the 3D printing process, such as high porosity, low fibre content, and a very low fibre-aspect ratio (L/d). Hygromorph BioComposites (HBC) are categorized into a new class of smart materials that could be used for 4D printing of shape-changing mechanisms. Fibre content, fibre orientation control, and fibre continuity are outlined in relation to known challenges in actuation performance. Graphical abstract: Unlabelled Image Highlights: The current state of the art on 3D and 4D printing of biocomposites based on natural fibres was achieved. The 3D printing data was delivered from the production of the filaments to the tensile properties of the printed biocomposite. The 4D printing data of biocomposites were analyzed in terms of actuation characterization. The relationship between slicing/printing parameters, microstructure and mechanical or actuation performance was analyzed. The future prospects on 3D/4D printing of biocomposites based on natural fibres were discussed.