3D and 4D printing: A review of virgin polymers used in fused deposition modeling

Recent advancements in additive manufacturing (AM), which includes both three-dimensional (3D) and four-dimensional (4D) printing, have revolutionized manufacturing processes across the board. Fused deposition modeling (FDM) is one of the most widespread 3D printing technique that enables the use of a wide range of virgin polymers and polymer-based composites to meet the demand for high-performance, intelligent, and self-assembling structures. Although polymer-based composites offer a variety of multifunctional properties, it is essential to comprehend the mechanical and microstructural properties of parts printed with virgin polymers to analyze and design the additives and reinforcements required to achieve the optimal desired functionalities. Overall, this review focuses on the adoption and applications of virgin FDM polymers and highlights different virgin polymers and equipment used in 3D and 4D printing. A comparative study on the mechanical and microstructural properties of various FDM polymers is also performed. In addition, this work also covers the state-of-the-art approaches and practices used for 4D printing of polymer-based systems and future directions for this field.