José H. Mina

Influence of Incorporation of Natural Fibers on the Physical, Mechanical, and Thermal Properties of Composites LDPE-Al Reinforced with Fique Fibers

This study shows the effect of the incorporation of natural fique fibers in a matrix formed by low-density polyethylene and aluminum (LDPE-Al) obtained in the recycling process of long-life Tetra Pak packaging. The reinforcement content was 10, 20, and 30% fibers, manufactured by hot-press compression molding of composite boards (LDPE-Al/fique). From the thermogravimetric analysis (TGA) it was determined that the proportions of the LDPE-Al were 75 : 25 w/w. Likewise, it was found that the aluminum particles increased the rigidity of the LDPE-Al, reducing the impact strength compared to LDPE recycled from Tetra Pak without aluminum; besides this, the crystallinity in the LDPE-Al increased with the presence of aluminum, which was observed by differential scanning calorimetry (DSC). The maximum strength and Young’s modulus to tensile and flexural properties increased with the incorporation of the fibers, this increase being a direct function of the amount of reinforcement contained in the material. Finally, a reduction in the density of the compound by the generation of voids at the interface between the LDPE-Al and fique fibers was identified, and there was also a greater water absorption due to weak interphase fiber-matrix and the hydrophilic fibers contained in the material.

Synthesis and Application of Scaffolds of Chitosan-Graphene Oxide by the Freeze-Drying Method for Tissue Regeneration

Several biomaterials, including natural polymers, are used to increase cellular interactions as an effective way to treat bone injuries. Chitosan (CS) is one of the most studied biocompatible natural polymers. Graphene oxide (GO) is a carbon-based nanomaterial capable of imparting desired properties to the scaffolds. In the present study, CS and GO were used for scaffold preparation. CS was extracted from the mycelium of the fungus Aspergillus niger. On the other hand, GO was synthesized using an improved Hummers-Offemann method and was characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, atomic force microscopy (AFM), X-ray diffraction (XRD), and dynamic light scattering (DLS). Subsequently, three formulations (GO 0%, 0.5%, and 1%) were used to prepare the scaffolds by the freeze-drying technique. The scaffolds were characterized by FTIR, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), to determine their thermal stability and pore size, demonstrating that their stability increased with the increase of GO amount. Finally, the scaffolds were implanted, recollected 30 days later, and studied with an optical microscope, which evidenced the recovery of the tissue architecture and excellent biocompatibility. Hence, these results strongly suggested the inherent nature of chitosan/graphene oxide (CS/GO) scaffolds for their application in bone tissue regeneration.