Fabrication & Characterization of Novel Sargassum-Based Polymer Composite Filaments for 3D Printing

As a direct effect of ocean warming and nutrient enrichment, tones of a brown macroalgae known as Sargassum, have been accumulating on shores throughout the Caribbean region since 2011. These unprecedented annual events have been detrimental to marine ecosystems, human health, and economy of coastal communities. In the search for new applications of Sargassum biomass, the present work aimed to explore the use of this seaweed as a raw material for the fabrication of renewable powder that was incorporated into polylactic acid (PLA) composite filaments to 3D print different specimens. The mechanical properties of the resulting structures were evaluated via tensile tests, while studies of biodegradability were performed using burial tests.

The materials characterization results indicate that the Sargassum processed via ball milling exhibited fine particles with a broad particle size distribution (microns). TEM analysis is required to observe the nanosized particles. This work also demonstrated that it is possible to fabricate filaments with Sargassum powder contents up to 30 wt%. However, the required extrusion temperatures and the brittleness of the filaments increase with the Sargassum content. Also, 3D printing of these composite materials required nozzles with sizes ≥1 mm to avoid clogging.

In terms of the mechanical properties, the elastic modulus and yield strength of the 3D printed specimens exhibited a declining trend as the Sargassum content into the PLA polymer matrix increased from 0 to 20wt%. These results are supported by the SEM analysis that shows that the number of defects and surface roughness increases with the biomass content. These defects are usually associated with poor mechanical behaviors. At higher filler contents (≥ 25 wt%), the variability in the elastic modulus was significant, making it difficult to draw precise conclusions. This variability is supported by the inhomogeneities, and defects observed in the microstructure of specimens with high Sargassum contents. The yield strength results followed a similar trend.

Burial test results indicate that the weight loss (wt%) of the fabricated specimens increases ~4.5 times as the biomass content increased from 0 to 30wt% (after 120 days).