Estudo da incorporação de nanopartículas de óxido de zinco e pentóxido de nióbio em polietileno linear de baixa densidade
Dantas, Ana Paula Silva
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Linear low-density polyethylene (LLDPE) is one of the most widely used materials in greenhouse covering, due to its low cost and transparency to photosynthetically active radiation up to 80%. However, this polymer also presents high transparency to ultraviolet (UV) and infrared radiation (IR), which is undesirable to the quality of the plants. In this context, the objective of this project was to study the addition of ZnO and Nb2O5 nanoparticles in LLDPE matrix aiming a potential application as greenhouse covering. Firstly, the nanoparticles were synthesized by co-precipitation and hydrothermal (ZnO) and hydrothermal (Nb2O5) synthesis, and their optical and structural characteristics were evaluated. Secondly, the composites were processed in an internal mixer, followed by hot pressing to obtain films, whose structure and optical, thermal and mechanical properties were characterized. The structural characterization showed no phase related to impurities of the nanoparticles, and the optical analysis reviewed that both nanoparticles absorbed UV and IR radiation. The microstructures of the composites showed that both nanoparticles agglomerated in the LLDPE matrix, but only ZnO nanoparticles presented a good distribution. Films containing ZnO had an increase in absorption of UV and IR radiation relative to LLDPE films; however, films containing Nb2O5 did not show a significant increase of these optical properties. The incorporation of nanoparticles also decreased crystallinity, but with an increase in thermal stability. The mechanical properties tended to increase for the composites containing ZnO; however, the addition of Nb2O5 significantly reduced tensile strength and elongation at break due to the presence of agglomerates.