Development of biocomposite based on cassava starch and eucalyptus fibers modified with silver nanoparticles
Name: LUISA BORGES DOS SANTOS
Publication date: 19/03/2025
Examining board:
Name |
Role |
|---|---|
| ELOI ALVES DA SILVA FILHO | Examinador Interno |
| MARCELO HENRIQUE PRADO DA SILVA | Examinador Externo |
| MARTA ALBUQUERQUE MACHADO | Presidente |
Summary: This study describes the production of a thermoplastic starch-based (ATP) biocomposite reinforced with eucalyptus fibers (FE) chemically treated and modified with silver nanoparticles by thermocompression technique. The fibers were subjected to an alkaline process, followed by bleaching by hydrogen peroxide. To investigate the particle size effect of the reinforcing fibers, biocomposites containing 20 %(w/w) fibers in the particle size ranges of 75–250 m (ATP/FE75), 250–600 m (ATP/FE250) e 600–1800 m (ATP/FE600) were prepared. Then, the effect of the reinforcement load content (5, 10, 20 and 30 %w/w) was evaluated, maintaining the fixed particle size (600–1800 m). Finally, silver nanoparticles were incorporated into the bleached fibers and the biocomposite (ATP/Ag@FE) containing the modified fibers was prepared in order to evaluate the influence of the modification. The treated fibers were analyzed by Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) to evaluate changes in the composition of the fibers and their crystal structure. All biocomposite samples formulated in this study were characterized by scanning light and electron microscopy, tensile tests, moisture absorption, and swelling. The sorption capacity of the biocomposites in petroleum/water emulsion was also evaluated. Micrographs revealed a higher matrix-fiber adhesion for the ATP/FE600 sample, which resulted in a 30% increase in maximum tensile strength, 63 % in tensile modulus and a 27 % reduction in elongation compared to the unreinforced sample. In contrast, tensile tests identified that a higher fraction of reinforcement fibers per volume of the biocomposite can impair adhesion, generating points of failure in the material. Regarding fiber content, the sample containing 10 %(w/w) showed an increase of 226 % in the maximum tensile strength and reduction of 63.9 % in elongation in relation to the sample without reinforcement. Meanwhile, samples containing 20 and 30 %(w/w) of fibers showed lower adhesion between the fiber and matrix, as evidenced by tensile tests and optical and scanning electron micrographs. In addition, surface modification with nanoparticles can improve the storage capacity of the material and can be applied to the treatment of oily emulsions, with a sorption capacity of the material of 53.8 %, and preserving the integrity of the material, slowing down the growth of microorganisms. The control of size and fraction, as well as the possibility of modifying the surface of the reinforcement material emerge as strategies to improve mechanical attributes and mitigate moisture/water absorption tendencies in starch-based biocomposites, contributing to sustainable and high-performance materials.
