Insights into flexural and impact properties of polymer based materials printed through fused filament fabrication: Progress in the last decade

The Fused Filament Fabrication is an economic 3D printing process to produce lightweight polymers-based structures. Therefore, it is drawing a consistently increasing interest from industry and researchers. Flexural and impact properties are two of the critical performance measures for gauging the integrity of the printed structures. Since 2014, numerous studies have been carried out on this topic, however, their holistic overview with a focus on the flexural and impact properties has been barely presented in the literature. The current article reviews the relationship between the process parameters, both operating and geometrical, and these properties in detail. The cause-effect relationship is thoroughly examined considering material effect. This allows the identification of the complex interactive effects and conducive ranges of the important parameters to effectively control the process for achieving the desired mechanical properties. The review establishes that the crystallinity of post-printed polymers is a crucial factor in controlling the mechanical properties, and filled polymers generally offer better properties than unfilled ones if the right filler given the desired properties is chosen. Topology optimization, recyclability of polymers through FFF, and retention of polymer properties after printing are also discussed as innovative trends. Finally, limitations and research gaps are identified, and the latest ideas are proposed as a way forward for further development of the FFF technology.