Polymer compatibility and interfaces in extrusion-based multicomponent additive manufacturing – A mini-review

One of the most widespread versions of additive manufacturing technologies (AM) is fused filament fabrication (FFF) or fused deposition modeling (FDM), using polymer melts to print freeform structures. Due to specific rheological and processing conditions, interlayer adhesion, shrinkage, and warpage problems, standard polymer grades do not always meet all requirements, so more polymers must be combined to achieve the optimum solution. These combinations include traditional blending technologies (with or without compatibilizer additives), reactive extrusion, and mixing incompatible phases with mechanical interlocking. Combining layers of different polymers in laminated structures, improving the interlayer strength of one-component prints, and developing core-shell filaments also require solving compatibility problems. This mini-review shows representative examples from blending engineering polymers, high-performance polymers, multilayer and coextruded structures, and biodegradable polymers and discusses the solutions characterizing the extrusion-based additive manufacturing technologies, which sometimes differ from multicomponent materials used in injection molding.