Overcoming Challenges in <scp>3D</scp> Printing of Polyolefins and Their Composites: A Review on Strategies for Improved Printability and Performance

ABSTRACT Polyolefins such as polyethylene and polypropylene are among the most widely produced thermoplastics globally due to their low cost, chemical resistance, and favorable mechanical properties. Despite their industrial importance, these polymers pose significant challenges in additive manufacturing, particularly in extrusion‐based techniques like fused deposition modeling and fused granulate fabrication. Their semi‐crystalline nature leads to shrinkage and warpage during cooling, while their low surface energy results in poor interlayer and bed adhesion. This review provides a comprehensive overview of the molecular structure, crystallinity, and catalyst systems of polyolefins, highlighting how these factors influence printability and performance. Strategies for mitigating shrinkage and warpage are critically examined, including thermal control, polymer blending, and the use of nucleating agents and fillers. Adhesion improvement methods such as the addition of compatibilizers, surface treatments, crosslinking, and thermal processing are also discussed. This review evaluates the use of recycled polyolefins and proposes material and process modifications aimed at overcoming challenges with degradation and inconsistency. Furthermore, the role of functional fillers, including talc, calcium carbonate, biocarbon, and nanoclays, is explored in the context of enhancing mechanical strength, dimensional stability, and sustainability. Through the integration of materials science, process engineering, and sustainable design, this review offers practical insights to advance the application of polyolefins in high‐performance additive manufacturing.