Development of Surface-Coated Polylactic Acid/Polyhydroxyalkanoate (PLA/PHA) Nanocomposites

This work reports on the design and development of nanocomposites based on a polymeric matrix containing biodegradable Polylactic Acid (PLA) and Polyhydroxyalkanoate (PHA) coated with either Graphite NanoPlatelets (GNP) or silver nanoparticles (AgNP). Nanocomposites were obtained by mechanical mixing under mild conditions and low load contents (<0.10 wt %). This favours physical adhesion of the additives onto the polymer surface, while the polymeric bulk matrix remains unaffected. Nanocomposite characterisation was performed via optical and focused ion beam microscopy, proving these nanocomposites are selectively modified only on the surface, leaving bulk polymer unaffected. Processability of these materials was proven by the fabrication of samples via injection moulding and mechanical characterisation. Nanocomposites showed enhanced Young modulus and yield strength, as well as better thermal properties when compared with the unmodified polymer. In the case of AgNP coated nanocomposites, the surface was found to be optically active, as observed in the increase of the resolution of Raman spectra, acquired at least 10 times, proving these nanocomposites are promising candidates as surface enhanced Raman spectroscopy (SERS) substrates

Synthesis and Characterisation of ASA-PEEK Composites for Fused Filament Fabrication

In this paper, a series of polymer composites made from acrylonitrile-styrene-acrylate (ASA) and poly (ether ether ketone) (PEEK) were manufactured. ASA acts as a polymer matrix while PEEK is loaded in the form of micro-particles that act as a reinforcing filler. The composites were compounded by single screw extrusion and then, different specimens were manufactured either via injection moulding (IM) or fused filament fabrication (FFF). Two different types of PEEK (commercial and reused) in different concentrations (3 and 6 wt.%) were tested and their influence in the mechanical, structural, and thermal properties were studied. It was observed that reused PEEK enhanced the stiffness and tensile strength and thermal stability of the composites both, for injected and printed specimens. This evidences the suitability of these composites as potential candidates as novel materials with enhanced properties following an approach of circular economy

Synthesis and Characterisation of Acrylic Resin-Al Powder Composites Suitable for Additive Manufacturing

Stereolithography is an additive manufacturing technology commonly used to build either prototypes or final parts. Nevertheless, the manufacture of structural parts has been ruled out owing to the poor mechanical properties of conventional UV-curable resins. Moreover, the inventory of available commercial resins is still limited and they exhibit low thermal and electrical conductivity values. In this work, some composite materials were designed using Al microparticles dispersed within an SLA commercial resin matrix. These composites overcame the difficulties caused by the light scattering effect during the photopolymerisation process in the SLA technology. Dispersion of the filler was characterised by means of SEM/EDX and AFM. The composites exhibited improved thermal and mechanical behaviour in comparison with the pristine resin. The simplicity of the synthesis method used to prepare the composites provides a convenient starting point to explore new ways of designing composites for SLA with improved mechanical and functional properties

A novel route for catalytic activation of peroxymonosulfate by oxygen vacancies improved bismuth-doped titania for the removal of recalcitrant organic contaminant

In this work, bismuth-doped titania (BixTiO2) with improved oxygen vacancies was synthesized by sol-gel protocol as a novel peroxymonosulfate (PMS, HSO5−) activator. HSO5− and adsorbed oxygen molecules could efficiently be transformed into their respective radicals through defect ionization to attain charge balance after their trapping on oxygen vacancies of the catalyst. XRD study of BixTiO2 with 5 wt% Bi (5BiT) revealed anatase, crystalline nature, and successful doping of Bi into TiO2 crystal lattice. The particle size obtained from BET data and SEM observations was in good agreement. PL spectra showed the formation rates of •OH by 3BiT, 7BiT, 5BiTC, and 5BiT as 0.720, 1.200, 1.489, and 2.153 μmol/h, respectively. 5BiT catalyst with high surface area (216.87 m2 g−1) and high porosity (29.81%) was observed the excellent HSO5− activator. The catalytic performance of 0BiT, 3BiT, 5BiT, and 7BiT when coupled with 2 mM HSO5− for recalcitrant flumequine (FLU) removal under dark was 10, 27, 55, and 37%, respectively. Only 5.4% decrease in catalytic efficiency was observed at the end of seventh cyclic run. Radical scavenging studies indicate that SO4•− is the dominant species that caused 62.0% degradation. Moreover, strong interaction between Bi and TiO2 through Bi-O-Ti bonds prevents Bi leaching (0.081 mg L−1) as shown by AAS. The kinetics, degradation pathways, ecotoxicity, and catalytic mechanism for recalcitrant FLU were also elucidated. Cost-efficient, environment-friendly, and high mineralization recommends this design strategy; BixTiO2/HSO5− system is a promising advanced oxidation process for the aquatic environment remediation

Baixa percepção de risco entre adolescentes espanhóis em relação ao consumo de álcool

Según los estudios recientes, los adolescentes españoles muestran una baja percepción del riesgo asociado al consumo de alcohol. El objetivo de la presente investigación es analizar los factores que favorecen esta baja percepción a partir de la opinión de un grupo de 32 profesionales/expertos en adolescencia, familia, escuela, medios de comunicación y políticas locales. Se utilizó una metodología cualitativa, fundamentada en Grounded Theory, a partir de la información obtenida mediante 5 grupos de discusión guiados por entrevistas semiestructuradas. Se identificaron 12 factores o subcategorías agrupados en 4 categorías generales: riesgo a corto plazo, inmediatez y percepción de invulnerabilidad (categoría ¿pensamiento adolescente¿); concepción benévola del alcohol, normalización del consumo y binomio alcohol-diversión (categoría ¿normas sociales¿); consumo habitual en los padres, inconsistencia verbal-no verbal en el modelado parental, consumo sin riesgo en los medios, consumo con resultados positivos en los medios (categoría ¿modelos sociales¿); excesivo contenido sanitario, riesgo a largo plazo (categoría ¿discurso preventivo¿). Tras discutir los resultados en el contexto de la literatura científica actual, se realizan varias propuestas con el objetivo de aumentar la percepción del riesgo en los adolescentes: incidir con mayor fuerza en contenidos sobre los riesgos a corto plazo del alcohol; orientar las estrategias educativas dirigidas al adolescente, también hacia los agentes de socialización, especialmente los padres; incidir en políticas centradas en la sustancia y en reducir la oferta.According to recent studies, Spanish adolescents show low perception of risk in alcohol consumption. The current study aims to analyze the factors that favor this low perception based on the opinion of a group of 32 professional experts on adolescence, family, school, mass media, and local policies. A qualitative methodology was used, based on Grounded Theory, using information from 5 focus groups guided by semi-structured interviews. Twelve factors or subcategories were identified, grouped in 4 general categories: short-term risk, immediacy, and perception of invulnerability (¿adolescent thinking¿ category); benevolent view of alcohol, normalization of consumption, and alcohol-entertainment binomial (¿social norms¿ category); parents¿ habitual consumption, verbal/non-verbal inconsistency in parental model, risk-free consumption depicted in the mass media, consumption with positive results in the media (¿social models¿ category); and excessive health content, long-term risk (¿preventive discourse¿ category). After discussing the results in the context of the current scientific literature, the article offers various proposals for increasing risk perception in adolescents: stronger impact of contents on short-term risks of alcohol; educational strategies targeted to adolescents to include agents of socialization, especially parents; and policies centered on the substance and reduction of supply.De acordo com estudos recentes, os adolescentes espanhóis mostram baixa percepção de risco em relação ao consumo de álcool. O estudo tem como objetivo analisar os fatores associados com a baixa percepção de risco, com base nas opiniões de um grupo de 32 especialistas em adolescência, família, escola, mídia e políticas locais. Foi utilizada uma metodologia qualitativa, baseada na Teoria Fundamentada, usando informações de cinco grupos focais orientados por entrevistas semi-estruturadas. Foram identificados 12 fatores ou subcategorias, agrupados em quatro categorias gerais: risco no curto prazo, imediatismo e percepção de invulnerabilidade (categoria de ¿pensamento adolescente¿); visão benevolente em relação ao álcool, normalização do consumo e binômio álcool-entretenimento (categoria de ¿normas sociais¿); consumo habitual pelos pais, inconsistência na comunicação verbal versus não verbal no modelo representado pelos pais, consumo isento de risco retratado pela mídia, consumo com resultados positivos na mídia (categoria de ¿modelos sociais¿) e excesso de conteúdo relacionado à saúde, risco no longo prazo (categoria de ¿discurso preventivo¿). Depois de discutir os resultados no contexto da literatura científica atual, o artigo oferece várias propostas para aumentar a percepção de risco entre os adolescentes: impacto mais forte de conteúdos sobre os riscos do álcool no curto prazo; estratégias educativas orientadas aos adolescentes para incluir os agentes da socialização, especialmente os pais, além de políticas centradas na substância e na redução da oferta.Departamento de Educación y Psicología SocialVersión del edito

La Responsabilidad Social Corporativa : un ámbito profesional propicio para el trabajo social

El desarrollo sostenible basa su conceptualización en torno a tres pilares fundamentales: económico, ecológico y social. Desde que saliera a la luz el Informe Brundtland, desarrollado por las Naciones Unidas en 1987, se han realizado considerables esfuerzos económicos y organizativos para incorporar estas tres dimensiones en las esferas política, legislativa, social, administrativa y empresarial. La materialización de estos tres pilares en el ámbito empresarial ha precisado de un método evaluativo que estructure y oriente las acciones corporativas hacia el desarrollo sostenible. Este proceso de revisión ha dado en llamarse Responsabilidad Social Corporativa (RSC). No obstante, hasta la actualidad, podría decirse que el ámbito social no ha tenido relevancia en la evaluación de la RSC de la empresa, adquiriendo mayor importancia los otros pilares, en especial, el ecológico, que ha sido acompañado de importantes políticas y medidas de mejora ambiental de las empresas. En los últimos años, por el contrario, se está otorgando más relevancia al factor social. Cada vez con mayor asiduidad, las empresas buscan un desarrollo que minimice los impactos sociales negativos y garantice prácticas acordes con los derechos humanos y respetuosas con las características de la población en la que están insertas. El proceso de evaluación de la RSC, implica el desarrollo de metodologías y técnicas propias del trabajo social, sin embargo, otras disciplinas como la psicología y las ciencias empresariales están tomando ventaja en la realización y ejecución de estas evaluaciones, distorsionando, por tanto, las posibilidades de desarrollo de un nuevo ámbito teórico, ejecutivo y laboral del trabajo social. Se hace necesaria, así, la movilización de todos los sectores del trabajo social para la inclusión de la RSC como ámbito emergente de la profesión, desarrollando nuevos métodos y técnicas capaces de evaluar y garantizar el compromiso empresarial con un desarrollo social sostenible

Synthesis and Characterisation of ASA-PEEK Composites for Fused Filament Fabrication

In this paper, a series of polymer composites made from acrylonitrile-styrene-acrylate (ASA) and poly (ether ether ketone) (PEEK) were manufactured. ASA acts as a polymer matrix while PEEK is loaded in the form of micro-particles that act as a reinforcing filler. The composites were compounded by single screw extrusion and then, different specimens were manufactured either via injection moulding (IM) or fused filament fabrication (FFF). Two different types of PEEK (commercial and reused) in different concentrations (3 and 6 wt.%) were tested and their influence in the mechanical, structural, and thermal properties were studied. It was observed that reused PEEK enhanced the stiffness and tensile strength and thermal stability of the composites both, for injected and printed specimens. This evidences the suitability of these composites as potential candidates as novel materials with enhanced properties following an approach of circular economy

Development of polymeric composite materials and prototypes with cork for large format additive manufacturing

The ADICORK project is associated with an agreement between the Ministry of Agriculture, Livestock, Fisheries and Sustainable Development of the Junta de Andaluc&iacute;a and the INNANOMAT research group of the University of C&aacute;diz. It is oriented to the development of industrial applications with polymer-based composite materials based on cork, which allow the manufacture of innovative value-added products, using the technology of Large Format Additive Manufacturing. This technology makes it possible to manufacture high-volume industrial products, compared to the usual additive manufacturing technologies. Some of the polymer bases studied to develop the composite materials presented in this communication, within the framework of the indicated project, are ABS, PET-G, PLA and ASA. The incorporation of cork in the form of a microparticulate powder, properly processed, has made it possible to achieve improvements in certain properties of the composite materials and, in some cases, after carrying out a screening, in the particle size. Among the properties that have been improved, the mechanical and thermal ones stand out. With the methodology developed, it has been possible to obtain recyclable and more sustainable composite materials than the starting polymeric material. This type of technology has made it possible to obtain attractive and differentiated products of complex geometries, based on and inspired by the territorial and natural origin of cork and its collection, which by other types of manufacturing processes could be impossible or very expensive to create. The sectors in which these developments make sense are varied and in this communication we will focus on the presentation of prototypes developed with the composite materials developed for the furniture, lighting and habitat sectors