Compósitos biodegradables elaborados a partir de almidón termoplástico y partículas de madera de fresno

Abstract

ResumenSe han incrementado los estudios para desarrollar productos biodegradables elaborados a partir de polímeros naturales, entre ellos el almidón, porque es un material muy prometedor para este propósito. El presente trabajo consistió en elaborar y describir biocompósitos de almidón de maíz reforzado con partículas de madera de fresno, por el método de termo-compresión. Los biocompósitos se elaboraron con tamaños de partícula de 425 µm, 600 µm y 1.4 mm, así como en diferentes proporciones (5, 10 y 20 %) y una matriz termoplástica (0 % partículas) fue utilizada como referencia. Los resultados obtenidos demostraron que es posible elaborar almidón termoplástico por el método de termo-compresión. Las partículas de madera de fresno incorporadas a la matriz termoplástica contribuyeron a mejorar la resistencia a la tracción y el módulo de elasticidad, con una buena interfase (matriz-partícula) observado en imágenes SEM. El tratamiento térmico (annealing) aplicado a las probetas tuvo un gran efecto en los resultados de resistencia a tracción. Los compósitos con 10 % y 20 % de partículas de madera y tamaño de partícula 600 µm presentaron los mayores valores de resistencia mecánica. Los biocompósitos son inflamables pero tienden a auto-extinguirse. Durante el proceso de plastificación ocurre una ligera degradación térmica que origina la aparición de grupos carbonilos. La incorporación de partículas de madera a la matriz termoplástica disminuyó la absorción de humedad.Palabras clave: Biocompósito, ensayo a la flama, puente de hidrógeno, tratamiento térmico, tratamiento húmedo, termo-compresión. AbstractThe number of studies to develop biodegradable products from natural polymers has increased, among which starch is outstanding because it is a promising material for this purpose. The present work describes the production and characterization of biocomposites of corn starch reinforced with wood particles of ash-tree, for the method of thermo-compression. The biocomposites was prepared with particle sizes, 425 µm, 600 µm and 1.4 mm, as well as, in different ratios (5, 10 and 20 %) and a thermoplastic matrix (0 % particles) was used as reference. The obtained results demonstrated that it is possible to elaborate thermoplastic starch by the thermo-compression method. The ash wood particles incorporated into the thermoplastic matrix contributed to improve the tensile strength and elongation modulus, showing a good interface (matrix-particle) observed in the SEM images. The thermal treatment (annealing) applied to the specimens had a great effect in the results of tensile strength. The composites with 10 and 20 % wood particles and of 600 µm particle size presented the major values of mechanical resistance. The biocomposites are flammable but tend to auto-extinguish. During the process of plastification occurs a slight thermal degradation which causes the formation of carbonyl groups. Incorporating wood particles to the thermoplastic matrix decreased moisture absorption.

Evaluation of the use of banana pseudostem with thermoplastic corn starch for the elaboration of biodegradable dishes

“…The maximum value was 2.26 MPa, which corresponded to T7, presenting non-significant differences with most of the treatments. This value was lower than the one reported by Barrios et al (2015), who obtained values between 5 and 6 MPa with ash fibers and TPS. They concluded that increasing the amount of lignocellulosic fiber improves the mechanical performance of the composite material, being confirmed by (Cheng, 2019) that by increasing the amount of TPS, the resistance decreases.…”

“…The T6 and T9 treatments had a higher amount of TPS, so their humidity was higher. Therefore, the humidity of the dishes varied in relation to the amount of TPS added because the greater the plasticizer, the more moisture absorption increases (Almario et al, 2018;Kuciel and Liber-Knec, 2009, as documented by Barrios et al, 2015).…”

“…In addition, a signal of absorbed water was observed at 1630 cm −1 with more pronounced peaks in NS and TPS with respect to T1. This may be due to the formation of intermolecular forces by hydrogen bonding between the starch and the fibers (Barrios et al, 2015).…”

“…The peak attributed to 1795 cm −1 corresponds to stretching vibrations of C=O groups in the plate sample, which unlike NS is not shown. The appearance of this group is given by the thermocompression process that produced a slight decomposition due to the temperature and processing time, without affecting the physicalmechanical properties (Wu, 2005, as cited in Barrios et al, 2015).…”

Characterization and Implementation of Cocoa Pod Husk as a Reinforcing Agent to Obtain Thermoplastic Starches and Bio-Based Composite Materials

“…On the other hand, considering the previous author, FFCH, with a particle size smaller than 53 µm, can contribute to a reduction in water vapor permeability. The above information can be related to research conducted by Barrios Guzmán et al, 2015 [ 38 ], who reported that the particle sizes that recorded higher σ max and E values were between 425 and 600 µm, while a particle size of 1.4 mm provided less effect on reinforcement.…”