Showing papers by "Eduardo Radovanovic published in 2014"

Development of composites based on recycled polyethylene/sugarcane bagasse fibers

Abstract: In this work, sugarcane bagasse fibers were used as filler in composites having recycled high-density polyethylene (PEr) as matrix. Because of the poor interaction between fibers surface and the PEr, the surface of bagasse was chemically modified. This modification consists of washing with water at 80°C, a mercerization process using sodium hydroxide and acetylation reaction with acetic anhydride. The chemical modification was characterized by Fourier transform infrared–horizontal attenuated total reflectance (FTIR-HATR) and 13C nuclear magnetic resonance spectroscopies (NMR), thermogravimetric analysis (TGA), and scanning electronic microscopy (SEM). The composites were prepared from modified and unmodified fibers into PEr matrix, containing 5, 10, and 20% (w/w) of fiber. The samples were processed by extrusion and molds were prepared by injection process in order to perform mechanical tests. These materials were analyzed by SEM, TGA, and the water uptake was evaluated. Also, their mechanical properties were analyzed. Morphological analysis indicated that the chemical modification of sugarcane bagasse increased the compatibility between matrix and reinforcement. Tensile, flexural, and impact tests showed that the mechanical properties of the composite were improved compared to PEr due to the presence of the fibers. POLYM. COMPOS., 35:768–774, 2014. © 2013 Society of Plastics Engineers

Unprecedented high plasmonic sensitivity of substrates based on gold nanoparticles

Abstract: This work focused on the plasmonic sensitivity of a substrate composed of gold nanoparticles (AuNp) and 3-aminopropyltriethoxysilane (APTES)-modified graphene oxide (GO-APTES). The multilayered system fabricated by dip-coating was analyzed by means of FTIR spectroscopy and scanning electron microscopy (SEM). The localized surface plasmon resonance (LSPR) band of AuNp was shifted from ca. 520 nm (monolayer of AuNp) to ca. 600 nm (multilayered with GO), which was a result of the agglomeration of AuNp. SEM micrographies revealed a system containing agglomerated grapheme oxide sheets on the substrate. An unprecedented sensitivity profile, determined in different refractive index (RI) media, was ca. 460 nm/RIU. The bio-sensitivity of the substrate was evaluated by immobilization of BSA on MUA-NHS-treated Au/GO, which presented a shift of 2.07 nm after binding to the protein.

Synthesis of zeolite from multilayer food packing and sugar cane bagasse ash for CO2 adsorption

Abstract: The X/A zeolite crystal mixtures were synthesized using sugar cane bagasse ash (SCBA) as a silicon source and multilayer food packing (MFP) as an aluminum source under hydrothermal conditions at 80 °C for 79–296 hours. The silicon was extracted by alkaline fusion for 40 min at 550 °C with an alkali–SCBA weight ratio of 1:1. The aluminum solution was obtained from MFP using NaOH 1 M (3:1 water–acetone) solution. The synthesized zeolites were analyzed by XRD, FTIR, SEM, and BET. In the XRD results, most of the signals were indexed to zeolite X, and some signals were indexed to zeolite A. The vibration bands in the region 1200–400 cm−1 suggested the presence of the double-six-ring (D6R) zeolite X structure. The crystal morphology is characteristic of the zeolite X, and the specific area found by the BET method was 810.47 m2 g−1. The zeolite with the higher specific area was applied in the CO2 adsorption process until it reached 25 bar by the gravimetric method. The experimentally adsorbed amounts were adjusted with the Langmuir, Freundlich, and Toth models.