Estudio de distintos parámetros radiactivos y medidas de mitigación energéticamente eficientes

[Resumen] El objetivo del presente estudio es la caracterización de distintos parámetros radiactivos y estudio de la influencia de dichos parámetros en la contaminación ambiental, así como posibles causas. Al mismo tiempo, se realiza una evaluación y valoración energética de la actuación de mitigación de radón llevada a cabo en el laboratorio de radiactividad ambiental situado en la Escuela Universitaria Politécnica de la Universidade da Coruña.Traballo fin de mestrado (UDC.EUP). Eficiencia e aproveitamento enerxético. Curso 2017/201

Aprende Física e divírtete: experiencia 2019/2020

Banco de experiencias de Aprendizaxe Servizo. Convocatoria 2019/202

Printability Study of a Conductive Polyaniline/Acrylic Formulation for 3D Printing

[Abstract] There is need for developing novel conductive polymers for Digital Light Processing (DLP) 3D printing. In this work, photorheology, in combination with Jacobs working curves, efficaciously predict the printability of polyaniline (PANI)/acrylate formulations with different contents of PANI and photoinitiator. The adjustment of the layer thickness according to cure depth values (Cd) allows printing of most formulations, except those with the highest gel point times determined by photorheology. In the working conditions, the maximum amount of PANI embedded within the resin was ≃3 wt% with a conductivity of 10−5 S cm−1, three orders of magnitude higher than the pure resin. Higher PANI loadings hinder printing quality without improving electrical conductivity. The optimal photoinitiator concentration was found between 6 and 7 wt%. The mechanical properties of the acrylic matrix are maintained in the composites, confirming the viability of these simple, low-cost, conductive composites for applications in flexible electronic devices.Xunta de Galicia; ED481A-2019/001Xunta de Galicia; ED431C 2019/17Goretti Arias-Ferreiro thanks the financial funding received from the Xunta de Galicia and the European Union (Program to support the predoctoral stage at SUG 2019 (ED481A-2019/001)). The authors would like to thank the financial support from Xunta de Galicia-FEDER (Program of Consolidation and structuring competitive research units (ED431C 2019/17))

3D printing light-curing acrylic resins with electrical properties based on polianiline and lignin

Programa Oficial de Doutoramento en Física Aplicada. 5021V01[Abstract] Advances in 3D printing, key to the new production models of Industry 4.0, require high-performance and environmentally friendly materials. Its application in sensors is especially attractive, allowing, at an affordable cost, the integration of electronics in manufacturing. The aim of this thesis is to develop new photocurable resins with electrical properties for 3D-DLP printing. Flexible resins have been designed based on acrylate monomers and nanofillers: polyaniline (PANI), PANI modified with lignin (PANI/Lignin) or with carbon nanotubes (PANI/MWCNT) and organosolv lignin. Structural characterization of the materials has been performed by TGA, FTIR, rheology, microscopy, and elemental analysis; special attention has been paid to matrix/filler compatibility, the mechanical and electrical (piezocapacitive and piezoresistive) properties. PANI has proven to be a valuable conductive filler for light-curable printable conductive resins. PANI modified with MWCNT improved the electrical conductivity of the resins, at the cost of increased heterogeneity. However, lignin, as part of the filler or additive, improved the homogeneity, surface finish and electrical properties of the composites. Finally, the obtained functional prototypes (printed sensors) validated the reproducibility and precision of the developed materials in real life conditions.[Resumen] El avance en impresión 3D, clave para los nuevos modelos productivos de la Industria 4.0, requiere materiales de altas prestaciones y respetuosos con el medioambiente. Su aplicación en sensores es especialmente atractiva permitiendo, a un coste asequible, la integración de la electrónica en la fabricación. El objetivo de esta tesis es desarrollar nuevas resinas fotocurables con propiedades eléctricas para impresión 3D-DLP. Se han diseñado resinas flexibles basadas en monómeros de acrilato y nanorellenos: polianilina (PANI), PANI modificada con lignina (PANI/Lignina) o con nanotubos de carbono (PANI/MWCNT) y lignina organosolv. La caracterización estructural de los materiales se ha realizado mediante TGA, FTIR, reología, microscopía y análisis elemental; se ha prestado especial atención a la compatibilidad matriz/relleno, las propiedades mecánicas y eléctricas (piezocapacitivas y piezorresistivas). La PANI ha demostrado ser un relleno conductor valioso para resinas conductoras imprimibles fotocurables. La PANI modificada con MWCNT mejoró la conductividad eléctrica de las resinas, a costa de una mayor heterogeneidad. Sin embargo, la lignina, como parte del relleno o aditivo, mejoró la homogeneidad, acabado superficial y propiedades eléctricas de los compuestos. Finalmente, los prototipos funcionales (sensores impresos) obtenidos validaron la reproducibilidad y precisión de los materiales desarrollados en condiciones reales de uso.[Resumo] O avance en impresión 3D, clave para os novos modelos produtivos da Industria 4.0, require materiais de altas prestacións e respectuosos co medio ambiente. A súa aplicación en sensores é especialmente atractiva permitindo, a un custo alcanzable, a integración da electrónica na fabricación. O obxectivo desta tese é desenvolver novas resinas fotocurables con propiedades eléctricas para impresión 3D-DLP. Deseñáronse resinas flexibles baseadas en monómeros de acrilato e nanorecheos; polianilina (PANI), PANI modificada con lignina (PANI/Lignina) ou con nanotubos de carbono (PANI/MWCNT) e lignina organosolv. Realizouse unha caracterización estrutural dos materiais mediante TGA, FTIR, reoloxía, microscopía e análise elemental; prestouse especial atención á compatibilidade matriz/recheo, ás súas propiedades mecánicas e eléctricas (piezocapacitivas e piezorresistivas). A PANI demostrou ser un recheo condutor valioso para resinas condutoras imprimibles fotocurables. A PANI modificada con MWCNT mellorou a condutividade eléctrica das resinas, á conta dunha maior heteroxeneidade. Porén, a lignina, como parte do recheo ou aditivo, mellorou a homoxeneidade, acabado superficial e propiedades eléctricas dos compostos. Finalmente, os prototipos funcionais (sensores impresos) obtidos validaron a reproducibilidade e precisión dos materiais deseñados en condicións reais de uso

Lignin as a high-value bioaditive in 3D-DLP printable acrylic resins and polyaniline conductive composite

[Abstract]: With increasing environmental awareness, lignin will play a key role in the transition from the traditional materials industry towards sustainability and Industry 4.0, boosting the development of functional eco-friendly composites for future electronic devices. In this work, a detailed study of the effect of unmodified lignin on 3D printed light-curable acrylic composites was performed up to 4 wt.%. Lignin ratios below 3 wt.% could be easily and reproducibly printed on a digital light processing (DLP) printer, maintaining the flexibility and thermal stability of the pristine resin. These low lignin contents lead to 3D printed composites with smoother surfaces, improved hardness (Shore A increase ~5%), and higher wettability (contact angles decrease ~19.5%). Finally, 1 wt.% lignin was added into 3D printed acrylic resins containing 5 wt.% p-toluensulfonic doped polyaniline (pTSA-PANI). The lignin/pTSA-PANI/acrylic composite showed a clear improvement in the dispersion of the conductive filler, reducing the average surface roughness (Ra) by 61% and increasing the electrical conductivity by an order of magnitude (up to 10-6 S cm-1) compared to lignin free PANI composites. Thus, incorporating organosolv lignin from wood industry wastes as raw material into 3D printed photocurable resins represents a simple, low-cost potential application for the design of novel high-valued, bio-based products.Xunta de Galicia ; ED481A-2019/001Ministerio de Ciencia e Innovación ; PID2020-116976RB-I00Xunta de Galicia ; ED431C 2019/17Xunta de Galicia ; ED431B 2019/4

Polyethylene/ Poly(3-hydroxybutyrate-co-3-hydroxyvalerate /Carbon Nanotube Composites for Eco-Friendly Electronic Applications

Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] The development of new conducting composites, for electric and electronic applications, with lower environmental impact is a relevant issue. Blending poly (3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) with high-density polyethylene (HDPE), 50/50 HDPE/PHBV, and multiwalled carbon nanotubes (MWCNTs) (3.5 and 7.5%), represents a suitable strategy for improving sustainability of conducting polymers while maintaining procesability and functional performance. The study focuses on thermal, mechanical, morphological, rheological, electrical properties and EMI shielding effectiveness. Composites show a morphology in which MWCNTs remains in HDPE phase. Without compatibilizer, only the composite with 7.5% of MWCNTs achieves a conductivity value suitable for reaching 20 dB of electromagnetic shielding. In composites with PE grafted with maleic anhydride (0.5%) the electrical conductivity substantially increased, achieving a suitable EMI shielding level with lower proportion of nanotubes (5 wt%). Summarizing, composites with reduced environmental impact, suitable for EMI shielding applications, have been obtained optimizing the MWCNTs amount and their dispersion.The authors would like to thank the financial support from Ministerio de Ciencia e Innovacion/FEDER (project ref; PID2020-116976RB-I00) and Xunta de Galicia-FEDER (Program of Consolidation and structuring competitive research units (ED431C 2019/17). Furthermore, the authors thank the financial funding received from the Xunta de Galicia and the European Union (Program to support the predoctoral stage at SUG 2019 (ED481A-2019/001)). Finally, the authors thank the Fundação para a Ciência e Tecnologia (FCT) for financial support in the framework of the Strategic Programs UID/FIS/04650/2020 and the grant SFRH/BPD/110914/2015 (PC), as well as to the Basque Government Industry Departments for support under the ELKARTEK programXunta de Galicia; ED431C 2019/17Xunta de Galicia; ED481A-2019/001Portugal. Fundação para a Ciência e a Tecnologia (FCT); UID/FIS/04650/2020Portugal. Fundação para a Ciência e a Tecnologia (FCT); SFRH/BPD/110914/201

Photocurable printed piezocapacitive pressure sensor based on an acrylic resin modified with polyaniline and lignin

The design of suitable materials for the manufacture of pressure sensors with high sensitivity and flexibility in wearable electronics is still a challenge. In this study, a flexible and portable pressure sensor has been developed based on a photopolymeric formulation of polyaniline (PANI) /Lignin/acrylate. The amount of photoinitiator and the presence of lignin within the filler were investigated in order to obtain the best printability and capacitive response. Low PANI contents drastically increased the dielectric constant and 4 wt.% photoinitiator improved the signal and sensitivity. A sensitivity of 0.012 kPa-1 was achieved in a linear range (0 to 10 kPa) with only 3.5 wt.% PANI. Lignin improved both the dispersion of the filler within the matrix and the printability of the resin, due to lower absorptivity at the UV wavelength of the 3D printer. Thus, the PANI-Lignin filler was selected for the fabrication of a piezocapacitive prototype transducer. The pressure transducer demonstrated its practical application by responding to a human footfall and transmitting its corresponding electrical signal. This study shows the enhanced properties of lignin modified PANI acrylate composites. Based on lignin, an abundant natural waste, a sustainable photocurable cost-effective polymer is proposed for the fabrication of printable, wearable electronicsG.A.-F. would like to thank the financial funding received from the Xunta de Galicia and the European Union (Program to support the predoctoral stage at SUG 2019 (ED481A-2019/001)) and the Iacobus program (Candidature n degrees 35, 2020/2021 edition). The authors would like to thank the financial support from Ministerio de Ciencia e Innovacion/FEDER (project ref; PID2020-116976RB-I00) and Xunta de Galicia-FEDER (Program of Consolidation and structuring competitive research units (ED431C 2019/17 and ED431B 2019/44)). Furthermore, the authors thank FCT - Portuguese Foundation for Science and Technology for funding under Strategic Funding UIDB/00319/2021 and grant SFRH/BPD/110914/2015 (P.C.). Financial support from the Basque Government Industry under the ELKARTEK program is also acknowledged. Funding for open access charge: Universidade da Coruna/CISUG

Flexible 3D printed acrylic composites based on polyaniline/multiwalled carbon nanotubes for piezoresistive pressure sensors

The development of tunable UV-curable polymeric composites for functional applications, taking into consideration environmental issues and additive manufacturing technologies, is a research topic with relevant challenges yet to be solved. Herein, acrylic composites filled with 0–3 wt.%. polyaniline/ multiwalled carbon nanotubes (PANI/MWCNT) are prepared by Digital Light Processing (DLP) in order to tailor morphology, thermal, mechanical, and electromechanical properties. Viscosity, real-time infrared spectroscopy, and cure depth tests allow optimizing resin composition for suitable DLP printing. 2 wt.% is the maximum filler content reproducibly embedded in the polymer matrix. The advantages of PANI/MWCNT (50/50 wt.%) compared with single-component composites include safety issues, enhanced printability, increased electrical conductivity and thermal stability, and lower electrical percolation threshold (0.83 wt.%). Above this threshold the composites display excellent piezoresistive response, no hysteresis, and stability for over 400 compression cycles. The pressure sensibility (PS) of 2 wt.% composites decreases with applied pressure from PS ≈ 15 to 0.8 Mpa−1 for maximum pressures of 0.02 and 0.57 MPa, respectively. A proof-of-concept of the functionality of the novel materials is developed in the form of a tactile sensor, demonstrating their potential for pressure sensing applications as cost-effective, sustainable, and flexible materials for printed electronics.Goretti Arias-Ferreiro would like to thank the financial funding received from the Xunta de Galicia and the European Union (ED481A-2019/001). The authors would like to thank the financial support from Ministerio de Ciencia e Innovacion/FEDER (reLiCom3D project ref PID2020-116976RB-I00) and Xunta de GaliciaFEDER (ED431C 2019/17). Furthermore, the authors thank FCT - Portuguese Foundation for Science and Technology for funding under Strategic Funding UIDB/00319/2021 and grant SFRH/BPD/110914/2015 (P.C.). Financial support from the Basque Government Industry under the ELKARTEK program is also acknowledged. Funding for open access charge: Universidade da Coruña/CISUG