5+1 imrmpt

Abstract

Abstract information

English title:	Enhancement of the mechanical properties of carbon polymer nanocomposites through the simultaneous application of ultrahigh shear rates and very high pressures
Spanish title:	Mejora de las propiedades mec�nicas de nanocomposites polim�ricos de carbono a trav�s de la aplicaci�n de muy altas presiones y cizalladura
English abstract:	In many of the main industrial sectors such as automotive or aerospace, composite materials are meant to be the alternative to metallic materials. Among its benefits, the light-weighting of transportation can reduce considerably the fuel consumption and the emissions. However, its mechanical properties are still far away from the metallic materials. Graphene and its derivatives are emergent materials causing significant impact in numerous research fields. Their excellent mechanical, thermal, optical, and electrical properties make them attractive alternatives for multiple applications, the enhancement of the mechanical properties of materials is among them when used as nanofiller. For instance, from the theoretical point of view, the addition of graphene or graphene oxide to a polymer matrix considerably improves its mechanical properties -stiffness, strength, toughness-. However, from the experimental standpoint, the improvement is, by far, smaller than expected. This phenomenon is generally explained by four causes: the weak interface between the nanofiller and the matrix, the nanofiller misalignment, the non-homogeneous dispersion, and the nanofiller quality (big lateral size implies better mechanical behavior, a small number of layers leads to better performance, an increase of the number of defects and number and nature of free radicals worsen the mechanical properties but at the same time helps epoxy-filler adhesion). Current researches focus on these issues. Chemical functionalization of the polymer is a popular solution, however, the worsen of other mechanical properties of the material, the use of additional chemicals in the process, and high cost are still not solved. In this work, a novel polymer nanocomposite manufacturing technique, which allows for a remarkable enhancement of the mechanical properties has been developed and optimized. The method allows for an improvement of the dispersion level and the nanofiller matrix interfacial adhesion and a reduction of the number of layers at each graphene or graphene oxide flake. The technique is based on the simultaneous application of high pressures and ultra-high shear rates. A considerable number of specimens have been manufactured with different parameter combinations. Young�s modulus, tensile strength, loss factor, and fracture toughness standardized tests were performed. Clear improvements were detected, especially in treated neat epoxy. For understanding the mechanisms that lead to the improvements, specimens were analyzed by different microscopy and spectroscopy techniques. Results show that the length of the polymer chains is substantially increased. In order to quantify the effect of the macro and nanoscale mechanisms leading to the measured improvements, a multiscale tool is also built in this thesis, that individually measures the influence of the nanofiller-matrix interfacial characteristics, as well as the nanofiller properties, dispersion, and orientation state.
Spanish abstract:	En muchos de los principales sectores industriales, automovil�stico y aeron�utico especialmente, los materiales compuestos est�n llamados a ser la alternativa a los materiales met�licos. Entre sus ventajas, destacar las considerables reducciones de peso que conllevan una reducci�n de consumo energ�tico y de emisiones. Sin embargo, sus inferiores propiedades mec�nicas y en algunos casos su alto coste los mantiene a la sombra de materiales como acero o aluminio. En la �ltima d�cada, el grafeno y sus derivados han atra�do una considerable atenci�n. Sus excelentes propiedades mec�nicas, �pticas, t�rmicas y el�ctricas lo convierten en una vers�til alternativa en distintas aplicaciones. Siendo una de las principales su uso como refuerzo (�filler�) de matrices polim�ricas, los materiales compuestos. Considerando el coste actual de este tipo de refuerzos y sus prometedoras propiedades, desde el punto de vista te�rico, peque�as adiciones de materiales graf�nicos a una matriz polim�rica conllevan notables mejoras en las propiedades mec�nicas del mismo. Sin embargo, en la pr�ctica, la mejora es escasa o hasta nula en ciertos casos. Este fen�meno es generalmente debido a cuatro causas principales: la d�bil interfaz matriz-nanofiller, la orientaci�n, la dispersi�n, el tipo de filler y la calidad de este (en especial la secci�n lateral). El conocimiento en profundidad y el control de estos factores implicar�a un acercamiento a los valores te�ricos esperados. Por ello muchas investigaciones actuales est�n centradas en subsanar estas cuestiones. En la literatura presente, los m�todos de funcionalizaci�n del pol�mero destacan como respuesta m�s popular y efectiva. Mediante la modificaci�n de la cadena qu�mica de la matriz, se facilita la adhesi�n y dispersi�n del filler. Sin embargo, la desventaja de estos m�todos es que conllevan el uso de elementos qu�micos, generalmente muy �cidos, que pueden da�ar la cadena polim�rica, son altamente contaminantes, tienen un efecto negativo sobre otras propiedades y un coste asociado. Ante esta problem�tica, en esta investigaci�n se plantea un m�todo de mejora puramente mec�nico basado en la exposici�n del material a altas presiones y esfuerzos de cortadura. A trav�s de este sencillo m�todo, que no modifica ni da�a la cadena polim�rica principal, econ�micamente viable, escalable y medioambientalmente respetuoso se muestran mejoras considerables en las propiedades mec�nicas, especialmente en la energ�a de fractura en los materiales polim�ricos. M�dulo de Young, resistencia a fractura y energ�a de fractura fueron analizados en un n�mero representativo de muestras. Adem�s a nivel microsc�pico se analizaron los cambios en la cadena polim�rica, mostrando alargamientos en la cadena polim�rica del mismo.
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Authors

Name	Institution	Email
Guillermo Fern�ndez Zapico	Triboblend	guillermo.fernandez@triboblend.com

Presentation

Room:	Earth
Date:	2 June 2021
Hour:	08:40 - 09:10

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5+1 IMRMPT
5+1 International Meeting for Researchers in Materials and Plasma Technology

Previous editions:
1st IMRMPT 2011
2nd IMRMPT 2013
3rd IMRMPT 2015
4th IMRMPT 2017
5th IMRMPT 2019

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