Purpose: This paper aims to summarize the up-to-date research performed on combinations of various biofibers and resin systems used in different three-dimensional (3D) printing technologies, including powder-based, material extrusion, solid-sheet and liquid-based systems. Detailed information about each process, including materials used and process design, are described, with the resultant products’ mechanical properties compared with those of 3D-printed parts produced from pure resin or different material combinations. In most processes introduced in this paper, biofibers are beneficial in improving the mechanical properties of 3D-printed parts and the biodegradability of the parts made using these green materials is also greatly improved. However, research on 3D printing of biofiber-reinforced composites is still far from complete, and there are still many further studies and research areas that could be explored in the future.Design/methodology/approach: The paper starts with an overview of the current scenario of the composite manufacturing industry and then the problems of advanced composite materials are pointed out, followed by an introduction of biocomposites. The main body of the paper covers literature reviews of recently emerged 3D printing technologies that were applied to biofiber-reinforced composite materials. This part is classified into subsections based on the form of the starting materials used in the 3D printing process. A comprehensive conclusion is drawn at the end of the paper summarizing the findings by the authors.Findings: Most of the biofiber-reinforced 3D-printed products exhibited improved mechanical properties than products printed using pure resin, indicating that biofibers are good replacements for synthetic ones. However, synthetic fibers are far from being completely replaced by biofibers due to several of their disadvantages including higher moisture absorbance, lower thermal stability and mechanical properties. Many studies are being performed to solve these problems, yet there are still some 3D printing technologies in which research concerning biofiber-reinforced composite parts is quite limited. This paper unveils potential research directions that would further develop 3D printing in a sustainable manner.Originality/value: This paper is a summary of attempts to use biofibers as reinforcements together with different resin systems as the starting material for 3D printing processes, and most of the currently available 3D printing techniques are included herein. All of these attempts are solutions to some principal problems with current 3D printing processes such as the limit in the variety of materials and the poor mechanical performance of 3D printed parts. Various types of biofibers are involved in these studies. This paper unveils potential research directions that would further widen the use of biofibers in 3D printing in a sustainable manner.

The manufacture of natural fiber and core preforms for biocomposite sandwich structures that bound together with fungal mycelium-based polymer is investigated. The complete manufacturing process involves: (1) cutting individual textile plies; (2) impregnating multi-ply layups with natural glue conducive to mycelium growth; (3) simultaneously forming, sterilizing and setting impregnated skins; (4) filling formed skins with mycelium-laden agri-waste; (5) allowing mycelium to colonize and bind together core substrate and skins into a unitized preform; (6) high temperature drying that also inactivates fungus; and (7) infusing skins with bioresin using resin transfer molding. Aspects of steps 3–6 related to the preform shells and sandwich structure are the main focus of this paper. Three-point bending tests are performed on dry, natural glue-bonded, four-ply specimens in a full-factorial experimental design, and test results are analyzed by analysis of variance (ANOVA) to assess process parameter effects and sensitivities along with environmental condition effects. New specimens are then made using the optimized process and tested for beam bending in creep within an environmental chamber that mimics the actual mycelium growth environment for three days. Two- and six-ply specimens loaded to provide identical maximum tensile stress in flexure are tested, and useful conclusions are drawn based on all creep test results. Finally, preforms in the shape of a viable commercial product are filled with mycelium-inoculated substrate, grown and dried, and part quality is evaluated based on the amount of skin ingrowth and deviation between the measured and desired shapes.

The mechanical properties of woven jute fiber-reinforced PLA polymer laminates additively manufactured through Laminated Object Manufacturing (LOM) technology are simulated using the finite element method in this work. Woven jute fiber reinforcements are used to strengthen bio-thermoplastic PLA polymers in creating highly biodegradable composite structures that can serve as one of the environmentally friendly alternatives for synthetic composites. A LOM 3D printer prototype was designed and built by the authors. All woven jute/PLA biocomposite laminated specimens made using the built prototype in this study had their tensile and flexural properties measured using ASTM test standards. These laminated structures were modeled using the ANSYS Mechanical Composite PrepPost (ACP) module, and then both testing processes were simulated using the experimentally measured input values. The FEA simulation results indicated a close match with experimental results, with a maximum difference of 9.18%. This study served as an exemplary case study using the FEA method to predict the mechanical behaviors of biocomposite laminate materials made through a novel manufacturing process.