A literature survey on structural integrity of 3D printed virgin and recycled ABS and PP compounds

Plastics are used in a wide range of engineering applications in different industrial sectors like electronics, automotive, construction, packaging, white goods. Thanks to a combination of low-cost, ease of manufacturing and processing, excellent physical and chemical properties combined with adequate mechanical properties for structural applications, a tremendous and continuous increase in the consumption of polymer materials has occurred worldwide. However, the flip side of this ever-increasing consumption is the huge amount of waste, leading to deleterious environmental, health and economic impacts. Besides the use of recycled plastics, another important factor contributes to a material-efficient approach in the manufacturing industry; it is the mechanical design for 3D printing (or additive manufacturing), where minimum material usage complying with lightweight stiffness and strength requirements is pursued by topology optimization. In this technical and economical international scenario, the present paper presents a bibliographic survey concerning the structural durability of additively manufactured recycled plastics and compounds. In particular, the paper is aimed at investigating the structural durability of three “families” of recycled plastics (rPlastic), i.e. rABS, rPP and rPP/glass fiber compound. Therefore, a literature survey regarding the considered materials will be presented by focusing on the influence of the 3D-printing process parameters on their mechanical and fatigue properties. Finally, a comparison between the results found in the literature of 3D-printed and traditionally manufactured polymers will be reported.