Preservación de las propiedades mecánicas del WPC frente a la radiación UV mediante el uso de nanotecnología.
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Date
2025
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Universidad de Concepción
Abstract
El incremento en el uso de plásticos de un solo uso y la baja tasa de reciclaje de polipropileno en Chile plantean la necesidad de materiales alternativos sostenibles y de alto desempeño. En este contexto, los compuestos madera–plástico (WPC) constituyen una alternativa viable, aunque presentan limitaciones frente a la degradación por radiación ultravioleta (UV). El objetivo de esta investigación es desarrollar y evaluar un WPC a base de polipropileno reciclado de la industria pesquera y residuos madereros, incorporando nanopartículas de ´oxido de zinc (ZnO) como estabilizante frente a radiación UV.
La metodología contempla la fabricación de pellets de polipropileno reciclado mediante extrusión, su mezcla con 20% de polvo de madera y la incorporación de 2% p/p de nano-ZnO. Posteriormente, se procesaron probetas por inyección y se sometieron a ensayos de tracción (ASTM D638) y a ciclos de envejecimiento acelerado (ASTM G154) hasta 1104 h de exposición.
Los resultados muestran que el aceite mineral al 5% mejora la procesabilidad del polipropileno reciclado, reduciendo obstrucciones en la extrusora. La incorporación de polvo de madera aumenta la rigidez del material, pero reduce en aproximadamente un 70% la deformación máxima respecto al polipropileno base. En cuanto al envejecimiento, el WPC sin aditivo retuvo un 40% de su esfuerzo máximo inicial tras 1104 h, mientras que el WPC+ con 2% de nano-ZnO conservó cerca de un 70%. Asimismo, la degradación cromática (∆E) fue tres veces menor en el WPC+ que en el WPC, lo que confirma la acción protectora del ZnO.
En conclusión, la hipótesis de investigación se cumple parcialmente. El nano-ZnO mejora la resistencia del WPC frente a la radiación UV y reduce significativamente la degradación estética, aunque la ganancia en esfuerzo máximo no alcanza el 30% proyectado. Este trabajo demuestra que la integración de materias primas recicladas con nanotecnología contribuye a prolongar la vida útil y el desempeño de los WPC, aportando a la economía circular y abriendo oportunidades de aplicación a mayor escala.
The increasing use of single-use plastics and the low polypropylene recycling rate in Chile highlight the need for sustainable and high-performance alternative materials. In this con text, wood–plastic composites (WPC) represent a viable option, although they exhibit lim itations when exposed to ultraviolet (UV) radiation. The objective of this research is to develop and evaluate a WPC based on recycled polypropylene and wood residues, incorpo rating zinc oxide (ZnO) nanoparticles as a UV stabilizer. The methodology involved the production of recycled polypropylene pellets through extru sion, their blending with 20% wood flour, and the addition of 2 wt% nano-ZnO. Subsequently, specimens were injection-molded and subjected to tensile testing (ASTM D638) and accel erated weathering cycles (ASTM G154) up to 1104 h of UV exposure. The results show that 5% mineral oil improved the processability of recycled polypropylene, reducing clogging during extrusion. The incorporation of wood flour increased the stiffness of the material but reduced its maximum strain by approximately 70% compared to neat polypropylene. Under accelerated weathering, neat WPC retained only 40% of its initial tensile strength after 1104 h, whereas WPC+ with 2 wt% nano-ZnO preserved about 70%. Likewise, the color degradation (∆E) in WPC+ was three times lower than in neat WPC, confirming the protective effect of ZnO. In conclusion, the research hypothesis is partially validated. The addition of nano-ZnO enhances the UV resistance of WPC and significantly reduces color degradation, although the gain in tensile strength did not reach the projected 30%. This work demonstrates that integrating recycled raw materials with nanotechnology can extend the service life and performance of WPC, contributing to the circular economy and opening opportunities for large-scale applications.
The increasing use of single-use plastics and the low polypropylene recycling rate in Chile highlight the need for sustainable and high-performance alternative materials. In this con text, wood–plastic composites (WPC) represent a viable option, although they exhibit lim itations when exposed to ultraviolet (UV) radiation. The objective of this research is to develop and evaluate a WPC based on recycled polypropylene and wood residues, incorpo rating zinc oxide (ZnO) nanoparticles as a UV stabilizer. The methodology involved the production of recycled polypropylene pellets through extru sion, their blending with 20% wood flour, and the addition of 2 wt% nano-ZnO. Subsequently, specimens were injection-molded and subjected to tensile testing (ASTM D638) and accel erated weathering cycles (ASTM G154) up to 1104 h of UV exposure. The results show that 5% mineral oil improved the processability of recycled polypropylene, reducing clogging during extrusion. The incorporation of wood flour increased the stiffness of the material but reduced its maximum strain by approximately 70% compared to neat polypropylene. Under accelerated weathering, neat WPC retained only 40% of its initial tensile strength after 1104 h, whereas WPC+ with 2 wt% nano-ZnO preserved about 70%. Likewise, the color degradation (∆E) in WPC+ was three times lower than in neat WPC, confirming the protective effect of ZnO. In conclusion, the research hypothesis is partially validated. The addition of nano-ZnO enhances the UV resistance of WPC and significantly reduces color degradation, although the gain in tensile strength did not reach the projected 30%. This work demonstrates that integrating recycled raw materials with nanotechnology can extend the service life and performance of WPC, contributing to the circular economy and opening opportunities for large-scale applications.
Description
Tesis presentada para optar al título de Ingeniero/a Civil Mecánico/a.
Keywords
Polímeros Propiedades mecánicas, Radiación ultravioleta, Nanotecnología Materiales