Modification of Nafion Membranes with Polyaniline to Reduce Methanol Permeability

The modification of Nafion membranes with polyaniline (PAni) has been studied as an alternative for reducing methanol crossover in direct methanol fuel cells (DMFC). The modification has been performed by directly polymerizing the PAni following two different routes: immersion (Naf-S-Y, where S mean surface and Y the number of hours exposition) and crossover (Naf-C-Y, where C means crossover). The former consist of exposing the membranes to a reactive solution containing the aniline, oxidant and catalyst; while in the latter the aniline and a solution with the oxidant and the catalyst are in different chambers separated by the membrane, thus forcing them to react inside it. The effect of the modification mechanism and the reaction times has been studied. The resulting membranes were extensively characterized by means of Fourier Transform Infrared (FTIR), ionic exchange capacity (IEC), water uptake (WU), methanol permeability and single direct methanol fuel cell performance. Chemical characterization revealed that the oxidation state of the polyaniline was in all cases emeraldine and the amount of PAni for an equivalent exposure time was bigger for the crossover route. The crossover route has proven to be more effective in decreasing the apparent methanol permeability of Nafion modified membranes up to 48% for the crossover sample with higher modification time when the polymerization is due inside the membrane such is the case of the composite Naf-C-Y membranes. The Direct Methanol Fuel Cells performances of membrane-electrode assemblies prepared with pristine Nafion and Nafion-PAni membranes were tested at 40, 60 and 80 degrees C under 2 M methanol concentration. The results are compared with those found for Nafion pristine membranes which power densities were 90, 65, 60 and 50 mW/cm(2) at 80 degrees C for Nafion, Naf-S-1, Naf-S-5 and Naf-C-2, membranes respectively.This research is in the frame of Support Program for Research and Development of the Polytechnic University of Valencia and the Ministry of Science and Innovation for funding provided through the projects: SP-ENE-20120718 and 24761, respectively.Gonzalez-Ausejo, J.; Cabedo Mas, L.; Gámez-Pérez, J.; Mollá Romano, S.; Giménez Torres, E.; Compañ Moreno, V. (2015). Modification of Nafion Membranes with Polyaniline to Reduce Methanol Permeability. Journal of The Electrochemical Society. 162(14):E325-E333. doi:10.1149/2.0521514jesSE325E3331621

Óptimo aprovechamiento de las sesiones de laboratorio

[EN] This paper shows the teaching experience applied to the laboratory sessions of the subject of Science and Technology of Materials that is taught in the second year of the degrees of Electrical Engineering, Mechanical Engineering and Industrial Technologies Engineering in the Universitat Jaume I. The purpose of this experience is to facilitate the learning of the basic theoretical knowledge related to laboratory practice to develop and to make the students aware of the importance of preparing the practice prior to its development. This has been done by developing and using means or transmission formats of the contents to know before the practice which are more attractive and visual than the existing practice script[ES] En este trabajo se muestra la experiencia docente aplicada a las sesiones de laboratorio de la asignatura de Ciencia y Tecnología de Materiales que se imparte en segundo curso de los grados de Ingeniería Eléctrica, Mecánica y en Tecnologías Industriales en la Universitat Jaume I. El propósito de esta experiencia es facilitar el aprendizaje de los conocimientos teóricos básicos relacionados con la práctica de laboratorio a desarrollar y sensibilizar a los alumnos sobre la importancia de preparar la práctica previamente a su desarrollo. Esto se ha realizado mediante el desarrollo y uso de medios o formatos de trasmisión de los contenidos a conocer previamente a la práctica que sean más atractivos y visuales que el guion de prácticas existente actualmente.Gonzalez Ausejo, J.; Oliver Valls, R.; Gámez Pérez, J.; Cabedo Mas, L. (2017). Óptimo aprovechamiento de las sesiones de laboratorio. En In-Red 2017. III Congreso Nacional de innovación educativa y de docencia en red. Editorial Universitat Politècnica de València. 157-165. https://doi.org/10.4995/INRED2017.2017.6823OCS15716

Three-dimensional printing of PLA and PLA/PHA dumbbell-shaped specimens of crisscross and transverse patterns as promising materials in emerging application areas: Prediction study

This is an accepted manuscript of an article published by Elsevier in Polymer degradation and stability on 18/08/2018, available online: https://doi.org/10.1016/j.polymdegradstab.2018.08.008 The accepted version of the publication may differ from the final published version.This paper presents ex-ante examination of advanced polymer materials to detect defects and define and minimize the potential failure of novel polymer products before they arise. The effect of build directions on the properties of dumbbell-shaped specimens obtained by three-dimensional printing from polylactide and polylactide/polyhydroxyalkanoate commercial filaments was investigated, as well as the hydrolytic degradation of these specimens at 50 ºC and 70 ºC. Taking into account previous studies, we have found further dependences of the properties of 3D printed species before and during abiotic degradation from the orientation of printing. The initial assumption that only the contact time with the 3D printer platform leads to an increase in the crystalline phase during printing turned out to be insufficient. Further investigations of individual parts of the dumbbell-shaped specimens showed that the size of the specimens’ surface in contact with the platform also affected the structural ordering of the material

A comparative study of three-dimensional printing directions: The degradation and toxicological profile of a PLA/PHA blend

The use of biobased plastics is of great importance for many applications. Blending thermoplastic polylactide (PLA) with polyhydroxyalkanoate (PHA) enables the formulation of a more mechanically powerful material and this enables tailored biodegradation properties. In this study we demonstrate the 3D printing of a PLA/PHA blend as a potential candidate for biocompatible material applications. The filament for 3D printing consisted of PHA, which contains predominantly 3-hydroxybutyrate units and a small amount of 3-hydroxyvalerate units, as revealed by multistage mass spectrometry (ESI-MSn). This research found that the properties of 3D printed species before and during abiotic degradation are dependent on printing orientation. Furthermore, the 3D printed specimens exhibited good biocompatibility with HEK293 cells, indicating real promise as biological scaffolds for tissue engineering applications

Pilot study describing the design process of an oil sump for a competition vehicle by combining additive manufacturing and carbon fibre layers

Formula Student is an international competition governed by the Society of Automotive Engineers (SAE) which challenges university students to design and build a racing car that will subsequently be compared against other cars from universities around the world on homologated racing circuits by non-professional drivers. This study focuses on the design, analysis and manufacturing process of a new oil sump for a Formula Student car - which involves combining a main ABS-plastic core created by an additive manufacturing (AM) printing process and a manual lay-up process with carbon fibre - in order to reduce the sloshing effect due to the movement of the oil during racing. The new oil sump and the original sump were modelled with computer-aided design (CAD) software and five computational fluid dynamics (CFD) simulations were performed to compare the sloshing effect in both designs in three driving scenarios: acceleration, braking and changing direction. The simulations showed that acceleration is not a critical situation since the new internal design of the sump was capable of delaying the immersion time of the oil pick-up pipe from 0.75 seconds to 2 seconds during braking and from 0.4 seconds to 0.8 seconds during lateral acceleration. The new design was physically manufactured and subsequently integrated into an internal combustion engine for testing for 45 minutes. During this test, the engine was started and put at 9600 RPM, so the oil worked under realistic temperature conditions (80 degrees C). It did not present any oil leak. After testing, it was disassembled and visually inspected. No failure in the inner surfaces of the oil sump was observed due to temperature. According to these results, the present research argues that the combination of AM technology (i.e., fused deposition modelling) and layers of carbon fibre is a real alternative to conventional manufacturing processes in order to create geometrically complex oil sumps that minimise the sloshing effect in competition automobiles