Syntactic foams are widely used in submarines like James Cameron's Deepsea Challenger and the next-generation Alvin deep-sea explorer because of their remarkable buoyancy and strength.

In two papers published in the Journal of the Minerals, Metals & Materials Society, Nikhil Gupta, an associate professor of mechanical and aerospace engineering, student researchers in his Composite Materials and Mechanics Lab at NYU Tandon's Mechanical Engineering Department, and collaborators in India informed that they have developed syntactic-foam filaments and processes to 3D print them using commercial printers.

The researchers developed filaments of high-density polyethylene plastic, a material used to manufacture industrial-grade components, and microspheres made of recycled fly ash. He mentioned that the process required the team to minimize crushing of the fragile hollow particles during mixing with the HDPE resin so that the resulting filament could have low density.

"The results show that the properties of 3D printed syntactic-foam components are at par with the widely used traditional injection-molded parts of the same material," Ashish Kumar Singh, a doctoral student, stated.

The research team will now focus on improving the material properties for numerous applications, like underwater vehicles capable of functioning at specific depths.