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Lignocellulosic waste materials are among the most abundant raw materials on Earth, and they have been widely studied as natural additives in materials, especially for polymer composites, with interesting results when it comes to improving physiochemical properties. The main components of these materials are cellulose, hemicellulose, and lignin, as well as small amounts of other polysaccharides, proteins, and other extractives. Several kinds of lignocellulosic materials, mainly fibers, have been evaluated in polymer matrices, and recently, the use of particles has increased due to their high surface area. Garlic is a spice seed that generates a waste husk that does not have applications, and there are no reports of industrial use of this kind of lignocellulosic material. Additive manufacturing, also known as 3D printing, is a polymer processing technique that allows for obtaining complex shapes that are hard to obtain with ordinary techniques. The use of composites based on synthetic polymers and lignocellulosic materials is a growing field of research. In the present work, the elaboration and evaluation of 3D-printed polypropylene–garlic husk particle (PP-GHP) composites are reported. First, the process of obtaining a filament by means of a single extrusion was carried out, using different GHP contents in the composites. Once the filament was obtained, it was taken to a 3D printer to obtain probes that were characterized using differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) was performed with the aim of evaluating the thermal behavior of the 3D-printed PP-GHP composites. According to the obtained results, the crystallization process and thermal stability of the PP-GHP composites were modified with the presence of GHP compared with pristine PP. Dynamic mechanical analysis (DMA) showed that the addition of GHP decreased the storage modulus of the printed composites and that the Tan δ peak width increased, which was associated with an increase in toughness and a more complex structure of the 3D-printed composites. X-ray diffraction (XRD) showed that the addition of GHP favored the presence of the β-phase of PP in the printed composites. [ABSTRACT FROM AUTHOR]

In recent years, the use of waste materials from agricultural sources has attracted interest as a research field. Several kinds of waste particles have been studied as additives for asphalt modification, and good results in terms of rheological and physical properties have been discussed in recent literature. In the present work, two types of seed shell particles were evaluated as asphalt modifiers. The shells of Jatropha curcas and pistachio are considered waste materials with no further industrial applications; therefore, in this study, they were incorporated into asphalt at different concentrations in order to evaluate their effect on the binder's properties. Modified asphalt mixtures were prepared through the hot mix method, and the physical, rheological, and thermal properties of the modified samples were measured and compared to those of the unmodified binder. According to the results of softening point, viscosity, and rheological characterization, the particles obtained from Jatropha curcas and pistachio shells can be used as efficient additives for asphalt modification. Pistachio shell particles act as an asphalt modifier, while Jatropha curcas behaves more like a filler agent since using it at high concentrations causes an inverse effect on the modified performance and properties of the asphalt. Finally, the results obtained showed that both shell particles were useful for improving the binder's resistance to rutting and permanent deformations, compared to the pure asphalt's original behavior. [ABSTRACT FROM AUTHOR]