17 research outputs found
Impact of Eucalyptus nitens and Pinus radiata fiber properties on the production process of lignocellulose nanofibrils
[EN] The physical and chemical properties of the plant cells that make up the raw material are diverse and affect the properties of lignocellulose nanofibrils (LCNFs). Due to their chemical differences, understanding the effect that the physical properties of the raw material confer on LCNFs is complex. This study aims at comprehending the impact that the physical properties and the chemical composition of the raw materials from Pinus radiata D. Don and Eucalyptus nitens Maiden have on the mechanical processes of fibrillation and the final properties of LCNFs. The anatomical, physical, and component differences of the fibers in the different fractions and species showed a non-effect on the longitudinal disintegration during the mechanical processes of fibrillation. In addition, the LCNFs produced from smaller fibers showed a smaller average width, with Eucalyptus nitens being the species that had smaller and more homogeneous nanofibrils. Nevertheless, the organization of the components (hemicellulose) from Pinus radiata on the surface of the fibrils, generates very hydrated and large fibrils and flocs, increasing the viscosities of the LCNF suspensions. A model was established between the intrinsic viscosity ( [ eta]) and aspect ratio ( p) of LCNFs ( rho[ eta] = 0.15p(1.68)) and delignified CNFs ( rho[ eta] = 0.031p(1.94)) that are independent of the pretreatments and the flexibility of the fibrils. Finally, the glass transition temperatures of lignin were not affected by physical changes in the raw material.This work was funded by the Agencia Nacional de Investigacion y Desarrollo (ANID)/Doctorado Nacional/2018-21181080, and projects FONDECYT No 1201042 and INNOMAT-H2 (MFA/2022/041) (Conselleria d'Innovacio, Universitats, Ciencia i Societat Digital).Albornoz-Palma, G.; Henríquez-Gallegos, S.; Ortega-Sanhueza, I.; Teruel-Juanes, R.; Ribes-Greus, A.; Pereira, M. (2023). Impact of Eucalyptus nitens and Pinus radiata fiber properties on the production process of lignocellulose nanofibrils. Cellulose. 30(8):4983-4999. https://doi.org/10.1007/s10570-023-05185-w4983499930
Estudio del efecto de la sulfonación y adición de óxido de grafeno a membranas de PVA para uso en pilas de combustible de metanol directo
Las membranas comerciales de Nafion son los electrolitos de referencia en las pilas de combustible de
membrana de intercambio protónico (PEMFC). Sin embargo, su elevado coste y su baja
conductividad, cuando la humedad no está controlada, limitan su aplicación a gran escala. En la
búsqueda de nuevos materiales, las membranas de alcohol polivinílico (PVA) entrecruzadas con ácido
sulfosuccínico (SSA) constituyen una alternativa económicamente viable, si se mejoran sus
propiedades de conductividad y su estabilidad mecánica. Con este fin se han preparado, por el método
de disolución-vertido, membranas de alcohol polivinílico entrecruzadas con SSA al 15% y 30%. El
PVA se modificó previamente por sulfonación, obteniéndose así las membranas (SPVA-82/SSA-18,
SPVA-70/SSA-30). También se le incorporó a la matriz polimérica de PVA, óxido de grafeno (GO) al
1% obteniéndose las membranas (PVA-81/GO-1/SSA-18, PVA-69/GO-1/SSA-30). Estas membranas
se caracterizaron en una monocelda de pila de combustible y se obtuvieron sus curvas de potencia. Se
ha observado que las membranas de alcohol polivinílico entrecruzadas con un 30% SSA y aditivadas
con óxido de grafeno presentan mejores resultados que las membranas comerciales. En el punto de
máxima potencia (MPP), las membranas podrían ordenarse de la siguiente forma: PVA-69/GO-
1/SSA-30 > SPVA-82/SSA-18 > SPVA-70/SSA-30 > PVA-81/GO-1/SSA-18 > PVA-83/SSA-17. Al
analizar la capacidad de intercambio iónico (IEC) se observa que ésta disminuye según el siguiente
orden: SPVA-70/SSA-30 > PVA-69/SSA-31 > PVA-69/GO-1/SSA-30 > SPVA-82/SSA-18 > PVA-
81/GO-1/SSA-18 > PVA-83/SSA-17. Los valores obtenidos indican que la sulfonación previa del
PVA aumenta la capacidad de intercambio protónico, al aumentar el número de puntos activos en la
membrana. Además, la adición de GO, por su singular estructura y su gran área superficial, favorece la
formación de canales transportadores de protones, especialmente en las membranas más entrecruzadas
y por tanto con mayor estabilidad mecánica. Estos resultados perfilan una metodología de diseño y
preparación de nuevos electrolitos con propiedades mejoradas, aplicables a las pilas de combustible de
intercambio protónico.Los autores quieren agradecer la ayuda aportada por la Generalitat Valenciana con la Beca Santiago
Grisolía, GRISOLIA/2013/03; al Ministerio de Economía y Competitividad por el programa de
investigación DOMEPOL, ENE2011-28735-C02-01, y la beca predoctoral FPI-BES-2012-055316
(EEBB-I-2014-08119)
Understanding the effect of lignin on the production process and characteristics of lignocellulose nanofibrils from Eucalyptus nitens
[EN] Cellulose, hemicellulose, and lignin are the main constituents of lignocellulose nanofibrils (LCNFs). The content and modification of lignin in the pulps affect the production process and characteristics of LCNFs, showing changes in their morphology, surface, rheological, and dielectric behaviors. Due to controversy and relevance in applications, these changes still need to be explained. This work seeks to understand the effect of lignin content and its oxidation on the production process and the characteristics of LCNFs. It was possible to produce pulps with fibers of similar physical characteristics and carbohydrate content after delignification, allowing the identification of the isolated effects of in situ lignin. A lower amount of lignin facilitated the LCNF production process, generating fibrils with smaller widths (up to similar to 48%) but more considerable apparent lengths (up to similar to 73%). In addition, the viscosity of the suspensions increased for LCNFs with lower lignin content (up to similar to 3.5 times to 0.5% (w/v)), due to increased flexibility, specific surface area, and surface charge of the fibrils. Finally, the LCNFs showed four dipolar relaxations, where the glass transition temperature of lignin decreased with oxidation and increased with increasing condensed structures and decreasing S/G ratio.This work was funded by the Agencia Nacional de Investigacion y Desarrollo (ANID)/Doctorado Nacional/2018-21181080, and projects FONDECYT N degrees 1201042, CORFO Grant no. 13CEI2-21839, and INNOMAT-H2 (MFA/2022/041) (Conselleria d'Innovacio, Universitats, Ciencia i Societat Digital).Albornoz-Palma, GPH.; Ortega-Sanhueza, I.; Teruel-Juanes, R.; Henríquez-Gallegos, S.; Ribes-Greus, A.; Pereira, M. (2023). Understanding the effect of lignin on the production process and characteristics of lignocellulose nanofibrils from Eucalyptus nitens. Cellulose. 30(11):6811-6831. https://doi.org/10.1007/s10570-023-05299-168116831301
Ionically conducting and photoresponsive liquid crystalline terpolymers : towards multifunctional polymer electrolytes
ARG and AMF thank the financial support of the Generalitat Valenciana, through the Grisolia and Forteza programs, and the Spanish Ministry of Science and Innovation, through the Research Projects ENE2007-67584-C03 and UPOVCE-3E-013 and the awarding of two FPI and FPU pre-doctoral grants. AMF and NFKA would like to thank the Royal Academy of Engineering for the award of the Newton Research Collaboration Programme grant NRCP1516/4/61. AMF acknowledges the School of Engineering of the University of Aberdeen for financial support.Peer reviewedPostprin
Estrategias Docentes Colaborativas para el Desarrollo de la Competencia Transversal de Innovación, Creatividad y Emprendimiento [Collaborative Teaching Strategies to Develop Skills in Innovation, Creativity and Entrepreneurship]
Una de las competencias transversales que entraña mayor grado de dificultad en su implementación, adquisición a todos los niveles, y evaluación es la de “Innovación, creatividad y emprendimiento”. La innovación se entiende como la capacidad de dar respuesta satisfactoria a las necesidades personales, organizativas y sociales, modificando procesos y/o resultados para generar nuevo valor. La innovación necesita ir acompañada de la creatividad para generar ideas y del emprendimiento para transformar las ideas en un producto de valor. En este trabajo se describe el diseño de estrategias docentes integradas en el marco de la corriente de educación emprendedora, centradas en el aprendizaje basado en problemas y colaborativo, para desarrollar dicha competencia. La acción se lleva a cabo en diferentes asignaturas de primer curso en distintos títulos de Grado en la Universitat Politècnica de València. Se describen las acciones realizadas, se analizan los resultados obtenidos y se valora la transferibilidad a otros contextos, tras la implementación del plan de trabajo para cada asignatura. Se concluye que las acciones llevadas a cabo han contribuido a desarrollar la competencia indicada y a que los estudiantes experimenten el valor del aprendizaje activo y del trabajo colaborativo.
[One of the most difficult transversal competences to implement, acquire at all levels and evaluate, is that of "Innovation, creativity and entrepreneurship". Innovation is understood as the ability to satisfy personal, organizational and social needs, modifying processes and/or results to generate new value. Innovation needs to be accompanied by creativity to generate ideas and by entrepreneurship to transform ideas into a valuable product. This paper describes the design of teaching strategies integrated within the framework of entrepreneurship education, focused on problem-based and collaborative learning, to develop this competence. The experiences are carried out in different first year subjects from different degrees offered by the Universitat Politècncia de València. After the implementation of the work plan for each subject, actions performed are described and results obtained are analysed in order to assess the transferability to other contexts. It is concluded that the actions carried out contributed to develop the indicated skill and allowed students to experience the value of active learning and collaborative work.
Assessing the influence of cotton fibers on the degradation in soil of a thermoplastic starch-based biopolymer
Biocomposites consisting of cotton fibers and a commercial starch-based thermoplastic were subjected to accelerated soil burial test. Fourier transform infrared (FTIR) spectrometry analysis was carried out to provide chemical-structural information of the polymeric matrix and its reinforced biocomposites. The effects that take place as a consequence of the degradation in soil of both materials were studied by FTIR-ATR, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). When the polymeric matrix and the reinforced biocomposite are submitted to soil burial test, the infrared studies display a decrease in the CO band associated to the ester group of the synthetic component as a consequence of its degradation. The crystalline index of both materials decreased as a function of the degradation process, where the crystalline structure of the reinforced biocomposite was the most affected. In accordance, the degraded reinforced biocomposite micrographs displayed a more damaged morphology and fracture surface than the degraded polymeric matrix micrographs. On the other hand, the same thermal decomposition regions were assessed for both materials, regardless of the degradation time. Kissinger, Criado, and Coats-Redfern methods were applied to analyze the thermogravimetric results. The kinetic triplet of each thermal decomposition process was determined for monitoring the degradation test. The thermal study confirms that starch was the most biodegradable polymeric matrix component in soil. However, the presence of cotton fiber modified the degradation rate of both matrix components; the degradability in soil of the synthetic component was slightly enhanced, whereas the biodegradation rate of the starch slowed down as a function of the soil exposure tim
Desarrollo de competencias mediante trabajos de investigación presentados y defendidos en entornos simulados dentro de las aulas
La Adaptación al Espacio Europeo de Educación Superior (EEES) exige recrear nuevos escenarios en las aulas, enfocados a vincular el mundo académico con el profesional. En esta comunicación se describe una estrategia docente basada en el descubrimiento guiado y diseñada específicamente para una asignatura de carácter experimental. Ésta se ha planteado siguiendo el esquema de un proceso de investigación, el cual anima a los alumnos a buscar, explorar, analizar y procesar de otro modo la información. El último peldaño es la divulgación de los resultados en un congreso científico simulado. Esta estrategia docente permite al alumno ser gestor de su aprendizaje y adquirir capacidades transversales útiles para su vida profesiona
Thermal characterisation of photo-oxidized HDPE/Mater-Bi and LDPE/Mater-Bi blends buried in soil
Blends of high and low density polyethylene with a commercial biodegradable material (Mater-Bi) were subjected to an accelerated soil burial test. A set of samples was previously photo-oxidized to evaluate the effects of UV-irradiation on the degradation in soil process of these blends. Thermogravimetric as well as calorimetric analysis were performed to study the biodegradation, photo-degradation and their synergetic effects. Differential scanning calorimetry was carried out to analyze the morphological changes as a consequence of the photo-oxidation process. UV-irradiation slightly modifies the crystalline content of HDPE/Mater-Bi blends, increasing the heterogeneity of this blend. Criado master curves were plotted to analyses the degradation kinetic model. Broido and Coats-Redfern methods have been used for calculating the Ea of the thermal decomposition mechanisms. Thermogravimetric results reveal that noncomplexed starch is more affected by biodegradation than the polyethylene matrix and the starch/ EVOH complexes chains from Mater-Bi. However, the effects of both photo-oxidation and biodegradation processes on the thermal decomposition of Mater-Bi is influenced by the polymeric matrix used. Previous photo-oxidation finds to slow down the degradative effects caused by the soil burial test on the HDPE/Mater-Bi blends
Dielectric analysis of photocrosslinked and post-sulfonated styrene-ethylene-butylene-styrene block copolymer based membranes
A series of UV photocrosslinked and post-sulfonated membranes based on blends of styrene-ethylene-butylene-styrene triblock copolymer (SEBS) and divinylbenzene (DVB) were considered for the preparation of electrolytes for proton exchange membrane fuel cell (PEMFC) applications. Macromolecular dynamics of SEBS and SEBS-DVB membranes below and above the T, were analysed using dielectric thermal analysis (DETA). A sub-Tg intramolecular non-cooperative dielectric relaxation and two main relaxations, corresponding to the glass transitions of ethylene-butylene (EB) and styrene (S) blocks, were identified in the dielectric relaxation spectrum. The photocrosslinking and post-sulfonation processes affect to the entire dielectric relaxation spectrum, the apparent activation energy and the fragilities of both styrene (S) and ethylene-butylene (EB) blocks. Understanding the restrictions on the segmental mobility at low and high scale caused by both photocrosslinking and subsequent sulfonation is basic to provide an approach to ionic diffusivities. A correlation between relaxations processes and the performance of these membranes in H/O – PEM single cells allows to estimate the behaviour of these membranes and to reengineer them, depending on the modification of the desired cell performance.The authors would like to thank the support of the European Union
is through the European Regional Development Funds (ERDF) and the
Spanish Ministry of Economy, Industry and Competitiveness, for the
research projects POLYDECARBOCELL (ENE2017-86711-C3-1-R),
REPICOMES (ENE2017-90932-REDT) and UPV- (PAID -10-19) SUB-1
grant for R. Teruel