3D printing of polymer composites: Materials, processes, and applications

Progress and potential The development of polymers is always closely linked with the advancement of polymer manufacturing and processing. Since the origination of additive manufacturing (AM) in the 1980s, there has been rapid development with increasing interest in AM technologies for polymers and their composite due to the advantages of high efficiency, resolution, and customization. However, AM requires certain conditions of polymers and composites (e.g., shape, physical, and rheological properties), and it offers limited application of AM in diverse industries. This paper provides directions to overcome these challenges by introducing the working principles of AM techniques for polymers and polymer composites and suggesting how to design and select polymers and filling materials for structural and functional applications. Finally, we share our perspective of potential problems and challenges in printing polymer composites as a guideline for the future development of polymer materials/chemistry and AM technologies. SUMMARY Additive manufacturing (AM) (also known as 3D printing) has enabled the customized fabrication of objects with complex geometries and functionalities in mechanical and electrical properties. AM technologies commonly use polymers and composites and have been advancing in a variety of industrial and emerging applications. Despite recent progress in 3D printing of polymer composites, many challenges, such as the suboptimal quality of manufactured products and limited material available for 3D printing, need to be addressed for the broad adoption of additively manufactured polymer composites. This review first provides a brief history of AM technologies along with 3D printing polymers. Subsequently, we discuss the state-of-the-art for the design of polymers and filling materials, the principles of AM processes, and emerging applications of 3D printed polymer and composites. Finally, we share our outlook of potential problems and challenges presented in AM of polymer composites, which might lead to future research directions.