Increment of specific heat capacity of solar salt with SiO2 nanoparticles

Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable.Universitat Jaume I (project P1-1B2013-43

Towards Competencies os Sustainability in Engineering Degrees: Project based service-learning experiences

Comunicació presentada al 13th International Conference on Society & Materials, SAM13 (Pisa, 20-21 May 2019)In the present work, a series of collaborative service-learning (SL) experiences carried out in the Universitat Jaume I de Castelló and University of the Basque Country will be presented. These experiences have been developed with in undergraduate courses,bachelor thesis and master thesis. The work points out how these experiences can serve as a toolf or teaching coordination at various levels: horizontal coordination with in a year in one degree, coordination between different degrees orinter-university coordination. The potential of these experiences makes them a very powerful methodological tool that can help not, only the students and the extra curricular agents involved, but also the teaching itself

Aprendizaje servicio+aprendizaje basado en proyectos: un binomio de éxito para trabajar el compromiso social y la ciencia de materiales en estudios universitarios de ingeniería

El aprendizaje basado en proyectos (ABP) ha demostrado ser una metodología eficaz para la adquisición de conocimientos y competencias clave en el ámbito universitario, del mismo modo las experiencias Service Learning (SL) permiten trabajar la Responsabilidad Social Universitaria (USR). Sin embargo, el nivel de adquisición de competencias depende en gran medida de la metodología docente empleada. En este trabajo se muestra la implementación y el desarrollo de una experiencia ABP de aprendizaje-servicio, en una asignatura de grado de ingeniería y en el ámbito de ciencia de los materiales. Se presentarán también los resultados obtenidos, así como las principales conclusiones a las que se ha llegad

Tailoring barrier properties of thermoplastic corn starch-based films (TPCS) by means of a multilayer design

This work compares the effect of adding different biopolyester electrospun coatings made of polycaprolactone (PCL), polylactic acid (PLA) and polyhydroxybutyrate (PHB) on oxygen and water vapour barrier properties of a thermoplastic corn starch (TPCS) film. The morphology of the developed multilayer structures was also examined by Scanning Electron Microscopy (SEM). Results showed a positive linear relationship between the amount of the electrospun coatings deposited onto both sides of the TPCS film and the thickness of the coating. Interestingly, the addition of electrospun biopolyester coatings led to an exponential oxygen and water vapour permeability drop as the amount of the electrospun coating increased. This study demonstrated the versatility of the technology here proposed to tailor the barrier properties of food packaging materials according to the final intended use.The authors acknowledge financial support from Spanish Ministry of Economy and Competitivity MINECO (AGL2015-63855-C2-1). M. J. Fabra is recipient of a Ramon y Cajal contract (RYC-2014-158) from MINECO

University Social Responsibility towards Engineering Undergraduates: The Effect of Methodology on a Service-Learning Experience

Service-Learning (SL) experiences enable University Social Responsibility (USR) to be worked on in engineering studies as a core of education for Sustainability. The combined use of such experiences with active student-centered teaching methodologies fosters the acquisition of general and specific competences. On the basis of students’ perception, this study investigated and sought evidence of empirical foundations to understand whether and how Project Based Learning (PBL) affects the acquisition of USR-related competences when SL experience was implemented as the regular exercise in core courses in engineering studies. This research studied 100 second year undergraduate students in Industrial Design Engineering and Product Development. The students were divided into two groups, one of which experienced Service-Learning only in one class activity while the other group carried out a PBL activity. A survey consisting of 28 items was delivered to all these students and their answers were analyzed from a descriptive statistics viewpoint to understand how the students perceived their degree of attainment of USR competences. The findings suggest a clear difference between the methodologies used, which shows that PBL methodology may lead to a greater acquisition of USR competences than SL activity

Biodegradable poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/thermoplastic polyurethane blends with improved mechanical and barrier performance

Papers presented at 5th International Conference on Bio-based and Biodegradable Polymers (BIOPOL-2015)Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) polymers pose a green alternative to fossil-fuel derived polymers, as they exhibit good biocompatibility, biodegradability and outstanding barrier performance compared to other biopolyesters. However, their excessive brittleness has not yet been overcome without compromising barrier performance. In this work, a native ester-based thermoplastic polyurethane (TPU) not stabilised against hydrolysis, has been thoroughly assessed for the first time as an additive in melt blends with PHBV. Phase segregation in scanning electron microscopy (SEM) confirmed the immiscibility of the two polymers, however a degree of interaction has been found. Wide-angle X-ray scattering and differential scanning calorimetry revealed no major effect of the TPU on the crystallinity of the PHBV phase. The onset and kinetics of thermal degradation was not altered by the presence of the TPU up to 50 wt% content. Blends with increasing TPU contents showed a gradual decrease in the modulus of elasticity and tensile strength, while a substantial increase in elongation at break has been found for contents of TPU above 20 wt%, which resulted an improvement in the overall toughness of the blends. The excellent barrier performance of the PHBV against water vapour and aroma compounds was shown to be unaffected by TPU loads of ≤30 wt%. Full decomposition of neat PHBV and PHBV/TPU blends below 50 wt% TPU content was achieved after 40 days according to biodisintegration standards (ISO 20200). The study puts forward the potential use of TPU to improve the mechanical performance of these natural biopolyesters without compromising the barrier properties or the biodisintegratibility of the melt blends.The authors wish to thank the European project ECOBIOCAP and the Ministry of Economy and Competitiveness under project MAT2012-38947-C02 for financial support. Jennifer Gonzalez-Ausejo gratefully acknowledges financial support under grant “Pla de promoció de la investigació en la Universitat Jaume I” Predoc/2012/32

Toughness Enhancement of Commercial Poly (Hydroxybutyrate-co-Valerate) (PHBV) by Blending with a Thermoplastic Polyurethane (TPU)

Poly(hydroxyl butyrate-co-valerate) (PHBV) is a biopolymer synthesized by microorganisms that is fully biodegradable with improved thermal and tensile properties with respect to some commodity plastics. However, it presents an intrinsic brittleness that limits its potential application in replacing plastics in packaging applications. Films made of blends of PHBV with different contents of thermoplastic polyurethane (TPU) were prepared by single screw extruder and their fracture toughness behavior was assessed by means of the essential work of fracture (EWF) Method. As the crack propagation was not always stable, a partition method has been used to compare all formulations and to relate results with the morphology of the blends. Indeed, fully characterization of the different PHBV/TPU blends showed that PHBV was incompatible with TPU. The blends showed an improvement of the toughness fracture, finding a maximum with intermediate TPU contents.Financial support for this research from Ministerio de Economía y Competitivi dad (project AGL2015-63855-C2-2-R (MINECO/FEDER) and Pla de Promoció de la Investigació de la Universitat Jaume I (PREDOC/2012/32 and E-2015-22) is gratefully acknowledged

On the relationship between the specific heat enhancement of salt-based nanofluids and the ionic exchange capacity of nanoparticles

Nanoparticles have been used in thermal applications to increase the specific heat of the molten salts used in Concentrated Solar Power plants for thermal energy storage. Although several mechanisms for abnormal enhancement have been proposed, they are still being investigated and more research is necessary. However, this nanoparticle-salt interaction can also be found in chemical applications in which nanoparticles have proved suitable to be used as an adsorbent for nitrate removal given their high specific surface, reactivity and ionic exchange capacity. In this work, the ionic exchange capacity mechanism for the nanoparticles functionalization phenomenon was evaluated. The ionic exchange capacity of silica and alumina nanoparticles dispersed in lithium, sodium and potassium nitrates was measured. Fourier-transform infrared spectroscopy tests confirmed the adsorption of nitrate ions on the nanoparticle surface. A relationship between the ionic exchange capacity of nanoparticles and the specific heat enhancement of doped molten salts was proposed for the first time

Mejora de la termoconformabilidad del PHBV mediante mezclas biodegradables con poliuretano

Actas del Congreso publicadas por ed. Compobell. ISBN 978-84-942655-8-7Mezclas de poli (3-hidroxibutirato-co-3-hidroxivalerato) (PHBV) y poliuretano termoplástico (TPU) se obtuvieron mediante extrusión con el objetivo de mejorar la procesabilidad del PHBV. La morfología, las propiedades mecánicas y la termoconformabilidad del PHBV se han evaluado observándose un aumento en la elongación a rotura y una mejora en el termoconformado del PHBV.A number of samples of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and thermoplastic polyurethane (TPU) were obtained through extrusion, with the aim of improving the processability of PHBV. The relevant assessment of PHBV’s morphology, mechanic properties, and thermoformability has been carried out, observing an increase in elongation at break and an improvement in the thermoforming of PHBV.Ministerio de Economía y Competitividad (proyecto MAT2012-38947-C02-01), Generalitat Valenciana (GV/2014/123) y Pla de Promoció de la Investigació de la Universitat Jaume I (PREDOC/2012/32)

Multilayer structures based on annealed electrospun biopolymer coatings of interest in water and aroma barrier fiber-based food packaging applications

In this research work, for the first time, a fiber-based packaging material was coated by annealed electrospun ultrathin fibers of poly(3-hydroxybutyrate), poly(vinyl alcohol), and polylactide. The resultant mono- and multilayer structures self-adhered to the paper substrate and were characterized in terms of morphology, optical, and barrier properties. Additionally, the use of a static flat plate and rotating mandrel collector as well as the application of different electrospinning deposition times were analyzed. The thermally treated electrospun biopolymers yielded totally transparent films while, due to the opaque nature of the uncoated paper substrate, the developed packaging materials were also opaque but with a glossier surface finish provided by the bioplastic coating. The annealed films obtained from random electrospun fibers, that is, the mats of ultrathin fibers collected on the static plate, presented higher transparency and thickness and also enhanced barrier performance. On the overall, the developed annealed electrospun biopolymer coatings resulted in a significant improvement of the paper barrier properties to water and limonene vapors, being the paper/poly(vinyl alcohol)/poly(3-hydroxybutyrate) film the best performing multilayer packaging structure