Browsing by Author "Cament, Alejandro"
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Item Mechanical and Antimicrobial Polyethylene Composites with CaO Nanoparticles(2020) Silva, Cristián; Bobillier, Felipe; Canales, Daniel; Sepúlveda, Francesca Antonella; Cament, Alejandro; Amigo, Nicolás; Rivas, Lina; Ulloa, María T.; Reyes, Pablo; Ortiz, J. Andrés; Gómez, Tatiana; Loyo, Carlos; Zapata, Paula ALow-density polyethylene composites containing different sizes of calcium oxide (CaO) nanoparticles were obtained by melt mixing. The CaO nanoparticles were synthesized by either the sol-gel or sonication methods, obtaining two different sizes: ca. 55 nm and 25 nm. These nanoparticles were used either as-synthesized or were modified organically on the surface with oleic acid (Mod-CaO), at concentrations of 3, 5, and 10 wt% in the polymer. The Mod-CaO nanoparticles of 25 nm can act as nucleating agents, increasing the polymer’s crystallinity. The Young’s Modulus increased with the Mod-CaO nanoparticles, rendering higher reinforcement effects with an increase as high as 36%. The reduction in Escherichia coli bacteria in the nanocomposites increased with the amount of CaO nanoparticles, the size reduction, and the surface modification. The highest antimicrobial behavior was found in the composites with a Mod-CaO of 25 nm, presenting a reduction of 99.99%. This strong antimicrobial effect can be associated with the release of the Ca2+ from the composites, as studied for the composite with 10 wt% nanoparticles. The ion release was dependent on the size of the nanoparticles and their surface modification. These findings show that CaO nanoparticles are an excellent alternative as an antimicrobial filler in polymer nanocomposites to be applied for food packaging or medical devices.Publication Mechanical and antimicrobial properties of low-density-polyethylene/MgO nanocomposites(2022) Cament, Alejandro; Moreno-Serna, Viviana; Loyo, Carlos; Quintana, Pabla; Seura, Pablo; Vallejos Baier, Raúl; Benavente, Rosario; Ulloa, María Teresa; Rivas, Lina; Pino, Eduardo; Gómez, Tatiana; Zapata, Paula A.Low-density polyethylene (LDPE) nanocomposites containing magnesium oxide (MgO) nanoparticles are obtained by melt mixing. MgO nanoparticles ca. 29 ± 2 nm are synthesized by sol–gel and organically modified on the surface with oleic acid (Mod-MgO), whose final concentration in the polymers is 3, 5, and 10 wt%. The presence of these nanoparticles did not affect the crystallization process of LDPE. However, Young's modulus increases with 10 wt% of Mod-MgO nanoparticles, rendering higher reinforcement effects with an increase as high as 48%. This affects the elongation at break, which decreases ca. 57% compared to neat LDPE. The storage and loss modulus of the LDPE/MgO and LDPE/Mod-MgO nanocomposites increases at room temperature and low temperatures ( 150 to 50C) compared to neat LDPE. SEM analysis showed that the organic modification of MgO nanoparticles improved their dispersion within the polymer matrix. Nanocomposites present antimicrobial properties against Escherichia coli, reaching an efficiency ca. 53%.