Estudio de la modificación superficial en fibras de carbono recicladas y su influencia en la interfaz fibra-matriz sobre las propiedades mecánicas de materiales de altas prestaciones.
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Date
2023
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Universidad de Concepción.
Abstract
Con el paso de los años, el uso de fibra de carbono en las industrias automovilística, aeroespacial y de energía ha generado un incremento en la demanda global de estos materiales, con una demanda esperada de 194 kt para el año 2022 y un valor de marcado global de $48.7 billones de USD. Sin embargo, existen problemas con el manejo de los residuos de estos materiales, ya que su manufactura produce un 30% de residuos y a esto se debe sumar todos los componentes dados de baja luego de cumplir su vida útil. Por este motivo es importante abordar una estrategia de reciclaje que permita reincorporar estos desechos a las diferentes industrias. El principal problema de las fibras recicladas es la disminución de sus propiedades mecánicas, específicamente su resistencia a la tracción, restringiendo el uso de estos materiales en aplicaciones de alta exigencia mecánica. Uno de los factores que influye en esta disminución de propiedades corresponde a la eliminación del sizing que recubre estas fibras, mecanismo de unión entre la fibra y la matriz. Otro factor corresponde a la estructura química y morfológica de la superficie de las fibras, las cuales se pueden degradar debido al uso de estos materiales (provocando microgrietas, por ejemplo). Considerando lo anterior, este proyecto tiene como objetivo estudiar la estructura y morfología de fibras de carbono recicladas por pirólisis que permita seleccionar un tratamiento superficial sencillo, mejorando las propiedades de adhesión fibra-matriz incorporando nanopartículas en un material compuesto reforzado con fibra de carbono reciclada. Se realiza un estudio de la estructura química y morfológica de las fibras de carbono recicladas, de tal forma de minimizar los daños en la superficie. Luego se investigan métodos para mejorar la interfaz fibra matriz, considerando el nivel de daño de la superficie de la fibra y las propiedades micromecánicas del material compuesto, de esta forma se pretende reparar y modificar la estructura superficial obteniendo una mejora en las propiedades de la interfaz y por consiguiente del comportamiento mecánico macroscópico de los materiales compuestos reciclados. Los métodos de reciclaje por pirólisis en dos pasos y pirólisis microondas permiten recuperar fibras de carbono en forma de tejidos a partir de materiales compuestos, el primero mantiene la integridad estructural y el segundo presenta mayor cantidad de grupos funcionales en la superficie de las fibras. Una vez nanoreforzados se observa que las nanopartículas de SiO2 favorecen las propiedades de adhesión fibra-matriz y los nanorods de ZnO mejoran las propiedades en tracción, sin embargo sólo es posible recuperar cerca del 70% de las propiedades originales de la fibra de carbono.
Over the years, the use of carbon fiber in the automotive, aerospace, and energy industries has generated an increase in global demand for these materials, with an expected demand of 194 kt by 2022 and a market value of USD 48.7 billion. However, there are problems with the management of waste from these materials since their manufacturing produces 30% waste, and due to this, all the components are discarded after reaching their useful life. For this reason, it is crucial to address a recycling strategy that allows these wastes to be reincorporated into different industries. The main problem with recycled fibers is the decrease in their mechanical properties, precisely their tensile strength, restricting the use of these materials in applications with high mechanical demands. One factor that influences this decrease in properties corresponds to the elimination of the sizing that covers these fibers, a binding mechanism between the fiber and the matrix. Another factor corresponds to the chemical and morphological structure of the surface of the fibers, which can degrade due to the use of these materials (causing microcracks, for example). Considering the above, this project aims to study the structure and morphology of carbon fibers recycled by pyrolysis. This allows for selecting a simple surface treatment, improving the fiber-matrix adhesion properties by incorporating nanoparticles in a composite material reinforced with recycled carbon fiber. A study of the recycled carbon fibers’ chemical and morphological structure is carried out to minimize surface damage. Methods are then investigated to improve the fiber-matrix interface, considering the level of damage to the fiber surface and the micromechanical properties of the composite material. In this way, it is intended to repair and modify the surface structure, improving the interface’s properties. Furthermore, consequently, the macroscopic mechanical behavior of the recycled composite materials. Recycling methods by two-step pyrolysis and microwave pyrolysis allow the recovery of carbon fibers in the form of fabrics from composite materials, the first maintaining structural integrity and the second presenting a more significant number of functional groups on the surface of the fibers. Once nanoreinforced, it is observed that the SiO2 nanoparticles favor the fiber-matrix adhesion properties, and the ZnO nanorods improve the tensile properties; however, it is only possible to recover about 70% of the original properties of the carbon fiber.
Over the years, the use of carbon fiber in the automotive, aerospace, and energy industries has generated an increase in global demand for these materials, with an expected demand of 194 kt by 2022 and a market value of USD 48.7 billion. However, there are problems with the management of waste from these materials since their manufacturing produces 30% waste, and due to this, all the components are discarded after reaching their useful life. For this reason, it is crucial to address a recycling strategy that allows these wastes to be reincorporated into different industries. The main problem with recycled fibers is the decrease in their mechanical properties, precisely their tensile strength, restricting the use of these materials in applications with high mechanical demands. One factor that influences this decrease in properties corresponds to the elimination of the sizing that covers these fibers, a binding mechanism between the fiber and the matrix. Another factor corresponds to the chemical and morphological structure of the surface of the fibers, which can degrade due to the use of these materials (causing microcracks, for example). Considering the above, this project aims to study the structure and morphology of carbon fibers recycled by pyrolysis. This allows for selecting a simple surface treatment, improving the fiber-matrix adhesion properties by incorporating nanoparticles in a composite material reinforced with recycled carbon fiber. A study of the recycled carbon fibers’ chemical and morphological structure is carried out to minimize surface damage. Methods are then investigated to improve the fiber-matrix interface, considering the level of damage to the fiber surface and the micromechanical properties of the composite material. In this way, it is intended to repair and modify the surface structure, improving the interface’s properties. Furthermore, consequently, the macroscopic mechanical behavior of the recycled composite materials. Recycling methods by two-step pyrolysis and microwave pyrolysis allow the recovery of carbon fibers in the form of fabrics from composite materials, the first maintaining structural integrity and the second presenting a more significant number of functional groups on the surface of the fibers. Once nanoreinforced, it is observed that the SiO2 nanoparticles favor the fiber-matrix adhesion properties, and the ZnO nanorods improve the tensile properties; however, it is only possible to recover about 70% of the original properties of the carbon fiber.
Description
Tesis para optar al grado de Doctor en Ciencia e Ingeniería de Materiales.