3D Printing of Polymer Matrix Composites. A Review and Prospective

3D printing, also known as additive manufacturing (AM), rapid prototyping (RP) or free-form solids manufacturing, refers to "a process in which materials are assembled, usually layer by layer, to make an object that conforms to the 3D data that models it". It was first described in 1986 by Charles Hull. This technology involves creating objects by depositing the material(s) within the contours defined by the 3D model. This reduces waste, since the geometric precision obtained is sufficiently precise to avoid the need for finishing the part to eliminate excess thickness and other burrs. The process begins with a 3D computer mesh, which can be created from image analysis data or structures defined from computer-aided design (CAD) software. This usually results in an STL (Surface Tessellation Language) file. The mesh data is then sliced to define a 2D layer configuration file that drives the 3D printer.

Thermoplastic polymer materials such as acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polyamide (PA) and polycarbonate (PC), as well as thermoset polymer materials such as epoxy resins, can be used in 3D printing. Epoxy resins are reactive materials that require thermal or UV-assisted cross-linking to complete the polymerization process. They initially have a low viscosity, which increases as curing progresses, and are therefore suitable for such a process. Depending on the choice of materials, polymer 3D printing has found possible applications in the aerospace industry for the creation of complex lightweight structures, architecture for the production of models, the art or education sectors, and the medical fields for the printing of tissues, organs or prostheses. However, most products made with polymer 3D printing are still used as conceptual prototypes rather than functional components, as their properties are still insufficient as functional and structural parts. Such drawbacks limit the use of 3D printed polymer parts for industrial applications.

3D printing of polymer composites seeks to solve these problems by combining matrix and reinforcements to achieve structural or functional properties that cannot be achieved by either component alone. The incorporation of particle, fiber or nanomaterial reinforcements enables the manufacture of polymer matrix composites featuring enhanced mechanical performance and excellent functionality. Conventional manufacturing techniques for composite materials, such as molding and casting, do not allow the creation of products with complex geometries. Machining, on the other hand, does. Although these manufacturing processes and the performance of composites made by these methods are well mastered, the ability to control the complex internal structure of the material is limited. 3D printing is capable of manufacturing...