Green Composites Based on Hedysarum coronarium with Outstanding FDM Printability and Mechanical Performance

Abstract

The addition of natural scraps to biodegradable polymers has gained particular interest in recent years, allowing reducing environmental pollution related to traditional plastic. In this work, new composites were fabricated by adding 10% or 20% of Hedysarum coronarium (HC) flour to Poly (lactic acid) (PLA). The two formulations were first produced by twin screw extrusion and the obtained filaments were then employed for the fabrication of composites, either for compression molding (CM) or by fused deposition modeling (FDM), and characterized from a morphological and mechanical point of view. Through FDM it was possible to achieve dense structures with good wettability of the filler that, on the contrary, cannot be obtained by CM. The results indicate that the filler effectively acts as reinforcement, especially for FDM composites. The most remarkable enhancement was found in the flexural properties (+100% of modulus and ultimate strength), followed by tensile resistance and stiffness (+60%) and impact strength (+50%), whereas a moderate loss in tensile deformability was observed, especially at the highest loading. By adding HC to the polymeric matrix, it was possible to obtain a green, high-performance, and cost-effective composite, which could find applications for the fabrication of panels for furniture or the automotive industry.

Green Composites Based on Mater-Bi® and Solanum lycopersicum Plant Waste for 3D Printing Applications

“…Nozzle temperature was chosen after some trials, aiming to avoid nozzle obstructions and to obtain good printability performance. The other parameters were chosen based on the scientific literature [ 16 , 17 , 24 , 25 , 26 ]. In particular, a 100% infill rate and a rectilinear infill pattern with a 0° or ±45° raster angle were chosen in order to evaluate its influence on the tensile properties of the composites; 45 mm/s printing speed was chosen to maximize the production rate without compromising the mechanical performance.…”

“…PO and in particular PO leaves (POL) have been investigated in several studies, focused on the structure–properties relationships; finding that the mechanical behaviour can be enhanced and, quite interestingly, that the degradability can be accelerated by the presence of POL [ 10 , 12 , 13 ]. HC is very abundant in the Mediterranean area and is known for applications in the agri-food sector [ 14 , 15 ] but has been recently investigated also regarding the formulation and preparation of green composites [ 16 , 17 ].…”

“…More specifically, there are some recent works where lignocellulosic wastes have been used as fillers for green composites and investigated for actual suitability to FDM manufacturing. HC was combined with Mater-Bi ® (MB) [ 16 ] or PLA [ 17 ] and the green composites were prepared via two different routes, i.e., compression moulding (CM) or FDM. It was found [ 16 ] that FDM could be preferable up to 10% HC content, leading to better mechanical properties (in particular, with regard to the elastic modulus) in comparison to CM, likely due to rectilinear infill and fibres orientation; furthermore, it was possible to get more dense structures than by CM [ 17 ], obtaining quite significant improvements of the mechanical properties (especially flexural ones) in comparison to the neat polymer.…”

“…HC was combined with Mater-Bi ® (MB) [ 16 ] or PLA [ 17 ] and the green composites were prepared via two different routes, i.e., compression moulding (CM) or FDM. It was found [ 16 ] that FDM could be preferable up to 10% HC content, leading to better mechanical properties (in particular, with regard to the elastic modulus) in comparison to CM, likely due to rectilinear infill and fibres orientation; furthermore, it was possible to get more dense structures than by CM [ 17 ], obtaining quite significant improvements of the mechanical properties (especially flexural ones) in comparison to the neat polymer. OFI and/or POL were investigated in combination with PLA and processed via FDM, finding that it was possible to replace up to 20% of the polymer matrix [ 24 ], with final samples characterized by good mechanical properties and satisfactory filler dispersion as well as filler–matrix adhesion, with very interesting potential applications in the release of fertilizers [ 25 ].…”

Hybrid biocomposites based on polylactic acid and natural fillers from Chamaerops humilis dwarf palm and Posidonia oceanica leaves

“…Nevertheless, its high production costs currently limit the use of PLA as a commodity [7,15,16]. Moreover, when combined with natural fillers, PLA often shows an undesired decay of tensile strength upon filler content [4][5][6][7]17]. On the other hand, hybrid composites containing two or more fillers are gaining a meaningful interest in the perspective of constructing composites having emerging properties exceeding the sum of those of single constituents [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”