In this study, the effect of the recycling process and copper particle incorporation on virgin and recycled pellet HDPE were investigated by thermo-chemical analysis, mechanical characterization, and antibacterial analysis. Copper particles were added to pellet HDPE, virgin and recycled, using a tabletop single screw extruder. Some copper particles, called copper nano-particles (Cu-NPs), had a spherical morphology and an average particle size near 20 nm. The others had a cubic morphology and an average particle size close to 300 nm, labeled copper nano-cubes (Cu-NCs). The thermo-chemical analysis revealed that the degree of crystallization was not influenced by the recycling process: 55.38 % for virgin HDPE and 56.01% for recycled HDPE. The degree of crystallization decreased with the addition of the copper particles. Possibly due to a modification in the structure, packaging organization, and crystalline ordering, the recycled HDPE reached a degree of crystallization close to 44.78% with 0.5 wt.% copper nano-particles and close to 36.57% for the recycled HDPE modified with 0.7 wt.% Cu-NCs. Tensile tests revealed a slight reduction in the tensile strength related to the recycling process, being close to 26 MPa for the virgin HDPE and 15.99 MPa for the recycled HDPE, which was improved by adding copper particles, which were near 25.39 MPa for 0.7 wt.% copper nano-cubes. Antibacterial analysis showed a reduction in the viability of E. coli in virgin HDPE samples, which was close to 8% for HDPE containing copper nano-particles and lower than 2% for HDPE having copper nano-cubes. In contrast, the recycled HDPE revealed viability close to 95% for HDPE with copper nano-particles and nearly 50% for HDPE with copper nano-cubes. The viability of S. aureus for HDPE was lower than containing copper nano-particles and copper nano-cubes, which increased dramatically close to 80% for recycled HDPE with copper nano-particles 80% and 75% with copper nano-cubes.

Este estudio desarrolla una metodología de aprendizaje colaborativo que permite reutilizar residuos generados en la academia, sin comprometer los objetivos de aprendizaje, y fomentar en los estudiantes una actitud medioambiental responsable. La metodología tiene cinco subsecciones: 1) identificación de cursos que generan residuos físicos en los programas curriculares vigentes; 2) análisis de la factibilidad técnica de la reutilización de los desechos identificados; 3) diseño de la propuesta de intervención; 4) implementación de la metodología; y 5) evaluación de la metodología. Los resultados muestran que el aprendizaje colaborativo permite a los estudiantes de primer año aprender de la experiencia y conocimiento de estudiantes de los últimos años, impulsando una carga cognitiva mayor y más eficaz que el aprendizaje individual. Adicionalmente, se logró reutilizar el 80% de residuos generados en actividades prácticas de docencia. Se concluye que la metodología implementada concientiza a los estudiantes sobre problemáticas medioambientales (residuos) a los que se verán enfrentados cuando ya sean profesionales.

No abstract

Wood is a sustainable and renewable material with a lower carbon footprint than other materials. However, its transformation into engineered products industrially, such as glulam, requires kiln drying, which implies energy consumption and loss of wood resources. Recent research has carried out green gluing, a variant of glulam characterized by a reduction of the drying process. Interest in it has increased as a new method of improving the use of wood that does not meet industry standards. It has been accomplished by developing adhesives for wood with high moisture content, but the variables involved are not yet completely understood. Therefore, conducting further research and analyzing the relevant publications is necessary. Bibliometric analysis was the method used, which included documents stored (from 2000 to 2020) in Scopus (Elsevier), Web of Science (Clarivate Analytics), and SciELO Citation Index (Web of Science—Clarivate Analytics) databases. The bibliometric analysis identified three main areas to develop: glue wood, glue properties, and analysis methods. The studies were concentrated on a few countries and research groups. The main progress has been made in synthetic and natural (or environmentally friendly) glue topics. The improvement of technique could enlarge the opportunities for collaboration and innovation in wood material science.

El principal objetivo de este estudio es reutilizar el hormigón de desecho de prácticas académicas y plásticos reciclados tipo PET (Polietileno Tereftalato) para la conformación de jardineras. Se propuso un diseño innovador de solerillas con pesos que oscilan entre 15 y 25 kg. Se caracterizan las mezclas de hormigón (0, 0,5 y 1,0% PET) y se hace un análisis de los aspectos de sustentabilidad de la solución. Los resultados indican que es posible alcanzar la resistencia mínima a la compresión de 15 MPa para todas las mezclas estudiadas. Con esta solución, se reutilizan 6 toneladas de hormigón al año, promoviendo el reciclado de hasta 40 botellas PET por solerilla, evitando anualmente la emisión de 40,66 kgCO2 y el consumo energético de 1.345,40 kWh. Se concluye que la solución de elementos prefabricados tipo solerilla para la construcción de jardineras es una alternativa para reducir hormigones en estado fresco que se desechan y para reciclar plástico del tipo PET.