José Antonio Silva-Guzmán

Polylactic acid functionalization with maleic anhydride and its use as coupling agent in natural fiber biocomposites: a review

Abstract Due to its renewability and biodegradability, biopolymers have developed interest in order to substitute oil-derived plastics. In particular, polylactic acid (PLA) is a promising biopolymer in terms of mechanical and biodegradable properties that is used for different applications. Nevertheless, PLA has some disadvantages like brittleness and processing instability. In order to overcome these drawbacks, it has been blended with natural fibers, leading to a fully biodegradable biocomposite material with enhanced properties. However, blending a hydrophobic biopolymer with hydrophilic fibers leads to poor interfacial adhesion producing interfacial voids, cavities and defects and consequently low performance properties. In this sense, this article reviews different strategies of biopolymer functionalization to improve compatibility in biocomposite materials. First, the effect of different parameters on biopolymers functionalization via melt and reactive extrusion processes is discussed. Finally, coupling efficiency of functionalized biopolymers is analyzed in terms of mechanical and thermal properties.

Properties of Thermoplastic Corn Starch Based Green Composites Reinforced with Barley (Hordeum vulgare L.) Straw Particles Obtained by Thermal Compression

Currently, greater environmental awareness promotes research and development advances in biodegradable materials; they represent an alternative that decreases the environmental impact caused by traditional synthetic plastics. This study consists of the development and characterization of thermoplastic corn starch-based composites, reinforced with barley straw particles made by thermal compression. The study materials were prepared by using three particle concentrations (5, 10, and 15 %), while the matrix (0 %) was used as a reference. A mechanical evaluation of all samples was carried out, as well as that of their water absorption properties. They were also characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), and flammability tests. The inclusion of straw in the thermoplastic matrix increased water absorption and quickened carbon formation, although it also increased its tensile strength (7 MPa) and the Young’s modulus of activity (MOE) (420 MPa) with a 15 % reinforcement. The FTIR analysis highlights the presence of a carbonyl signal (1720 cm-1) caused by a thermal breakdown (caramelization) linked to barley particles. Moreover, X-ray diffraction demonstrated a VA-type crystallinity pattern (anhydrous) within the biocomposites and an increase of the crystallinity index, through incorporating barley particles in the thermoplastic corn starch-based matrix.

Relationship of the cellular structure of teak wood ( Tectona grandis L. f.) with different ages and growth sites

Introduccion: Las caracteristicas celulares de la madera determinan las condiciones de procesamiento y uso de las especies forestales. Objetivo: Estudiar la variacion de las caracteristicas anatomicas en la parte interna y externa del duramen de Tectona grandis L. f. de diferentes edades y procedencias. Materiales y metodos: Se seleccionaron arboles de Campeche (9 y 15 anos), Tabasco (15 anos) y Chiapas (21 anos). Se hicieron cortes (10 y 20 µm de espesor) de las caras anatomicas (transversal, radial y tangencial) de la madera y se observaron en microscopio de campo claro. Las imagenes se capturaron con el software Matrox PC-VCR version 02.10.10. Los elementos celulares se midieron con el software ArcView GIS 3.2. Resultados y discusion: La madera de teca tuvo de 6 a 8 vasos·mm-². La madera de Campeche (9 y 15 anos) presento el mayor diametro de vasos en la parte interna y externa del duramen; en su parte interna, tuvo el mayor ancho de radios. En ambas partes del duramen, la madera de 9 anos de Campeche tuvo mayor altura de radios; la madera de Chiapas de 21 anos presento mayor longitud y diametro de fibras; y la madera de 15 anos de Tabasco produjo el mayor espesor de pared de fibras. Conclusiones: La edad y procedencia inciden sobre la estructura celular de la madera de teca