Additive Manufacturing of Syntactic Foams: Part 1: Development, Properties, and Recycling Potential of Filaments
This work focuses on developing filaments of high-density polyethylene (HDPE) and their hollow particle-filled syntactic foams for commercial three-dimensional (3D) printers based on fused filament fabrication technology. Hollow fly-ash cenospheres were blended by 40 wt.% in a HDPE matrix to produce syntactic foam (HDPE40) filaments. Further, the recycling potential was studied by pelletizing the filaments again to extrude twice (2×) and three times (3×). The filaments were tensile tested at 10−4 s−1, 10−3 s−1, and 10−2 s−1 strain rates. HDPE40 filaments show an increasing trend in modulus and strength with the strain rate. Higher density and modulus were noticed for 2× filaments compared to 1× filaments because of the crushing of some cenospheres in the extrusion cycle. However, 2× and 3× filament densities are nearly the same, showing potential for recycling them. The filaments show better properties than the same materials processed by conventional injection molding. Micro-CT scans show a uniform dispersion of cenospheres in all filaments.
Mrityunjay Doddamani acknowledges the Department of Science and Technology, India, Grant DST/TSG/AMT/2015/394/G, and Visiting Scientist Fellowship Grant VSP 17-7-001 by the US Office of Naval research—Global (Program manager: Dr. Ramesh Kolar) to visit NYU for this work. Nikhil Gupta acknowledges the Office of Naval Research Grant N00014-10-1-0988. The views expressed in this article are those of authors, not of funding agencies.
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