ANGEL VISENTIM ORTIZ

ANGEL VISENTIM ORTIZ

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Effect study of the incorporation of the Green Lake clay in the polypropylene homopolymer properties
2019 - SALES, J.N.; POVEDA, P.N.S.; ORTIZ, A.; VALENZUELA-DIAZ, F.R.; SILVA, L.A.
The advancement of technology has demanded the development of materials with increasingly lighter and more resistant properties. The development of nanocomposites first started in the mid-80s and contributed for obtaining materials with excellent properties. In this work, Green Lake clay was organophilized and incorporated into a commercial homopolymer polypropylene. The efficiency of organophilization was confirmed by water swelling analysis and, later, by Xray diffraction (XRD) analysis. Composites at 0.5, 1.0 and 2% by weight of clay/polypropylene were prepared by double screw extrusion. The properties of the composite were evaluated by means of Charpy impact resistance, tensile strength at rupture, thermogravimetric analysis (TGA). Crystallinity index was determined by differential scanning calorimetry (DSC). The organophilization processwas efficient, the thermogravimetric analysis showed that there was no decrease in the thermal stability of the composites when compared to pure polypropylene, and the results of the Charpy impact resistance were equivalent when compared to the commercial nucleant composites.
Mechanical, thermal, morphology and barrier properties of flexible film based on polyethylene-ethylene vinyl alcohol blend reinforced with graphene oxide
2017 - SANTANA, JULYANA G.; ORTIZ, ANGEL; OLIVEIRA, RENE R.; RANGARI, VIJAY K.; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B.
Ethylene-vinyl alcohol (EVOH) copolymers are widely used in the food packaging industry as gas barrier properties to oxygen, organic solvents, and food aromas. EVOH is very sensitive to moisture and its gas barrier ability deteriorates in high relative humidity conditions. This work aims to prepare flexible films based on melt-blending high density polyethylene (HDPE) and ethylene-vinyl alcohol (HDPE/EVOH/EVA blend) reinforced with graphene oxide (GO). The HDPE/EVOH/EVA/GO flexible films were prepared by twin-screw extrusion and blown film extrusion processing. The flexible films samples were characterized by tensile tests, TG, DSC and FE-SEM analysis and the correlation between properties was discussed. In addition, the oxygen permeability tests were performed at 23 °C, 0 and 90% relative humidity using an OX-TRAN (MOCON Inc.).
Preparation and characterization of PBT/clay nanocomposite
2012 - SARTORI, MARIANA N.; OLIVEIRA, RENE R.; DIAZ, FRANCISCO R.V.; ORTIZ, ANGEL V.; RANGARI, VIJAYA K.; MOURA, ESPERIDIANA A.B.
This work presents the preparation and characterization of a nanocomposite based on Poly(butylene terephthalate) PBT and Brazilian smectitic clay (bentonite chocolate clay). Before being incorporated as clay nanoparticles in PBT resin, the clay was organically modified by the addition of a quaternary salt and sodium carbonate. PBT/Clay nanocomposite (96.3:3.70 wt %) was obtained by using a twin-screw extruder machine. After extrusion process, the nanocomposite was characterized by tensile, flexural and impact tests, SEM, Vicat, HDT, DSC, TGA and XRD tests. The results showed that the properties of the nanocomposite obtained were superior to those of neat PBT. Concerning the temperature of thermal distortion (HDT) an expressive gain of around 45 % was presented to PBT/Clay nanocomposite compared to PBT evidencing the interaction of nanofiller with the polymeric matrix.
Comparison between HDPE/clay and HDPE/piassava fiber/clay treated by electron beam radiation
2013 - ORTIZ, ANGEL; ESCANHOELA, CORDELIA M.F.; GOMES, MICHELLE; OLIVEIRA, RENE R.; DIAZ, FRANCISCO R.V.; MOURA, ESPERIDIANA A.B.
This work evaluates changes in morphological, mechanical and thermo-mechanical properties of electron-beam irradiated HDPE/nanoclay and HDPE/Piassava fiber/nanoclay. Material samples irradiated with 100 and 200 kGy using a 1.5 MeV electron beam accelerator (room temperature, presence of air) were submitted to tensile, flexural, and HDT tests. MFI, SEM and XRD analyses were carried out. Correlation between properties was discussed. Results showed that incorporation of piassava (Attalea funifera Mart) fiber and nanoclay, followed by irradiation represented significant gain in thermo-mechanical properties. Changes in surface morphology and reduction in MFI were observed. In conclusion, it may be claimed that the incorporation of piassava fiber in small size particles and nanoclay in the HDPE followed by electron-beam irradiation effectively improved the polymer properties and led to materials with superior properties suitable for several industrial applications.
Thermal and morphological behavior of EVOH/piassava fiber composites
2012 - NOGUEIRA, BEATRIZ R.; CHINELLATO, ANNE; ORTIZ, ANGEL V.; PARVEEN, ARIFA; RANGARI, VIJAYA K.; MOURA, ESPERIDIANA A.B.
Composite consisting of ethylene vinyl alcohol (EVOH) with short piassava fibers were prepared by extrusion process and their thermal and morphological behavior were investigated. The EVOH reinforced with 5 and 10 % of piassava {Attaleafimifera Mart) fiber particle, based on the percentage weight ratio (wt %), untreated and treated with a commercial silane coupling agent, were prepared and the influence of fiber loading and the effect of chemical treatment on their thermal and morphological behavior were evaluated by SEM, DSC and TG analyses. Melt flow index (MFI) of the composites have been determined to evaluate the effects of fiber reinforcement on dynamic viscoelastic melt of the EVOH. In addition, piassava fibers characterization by SEM, FTIR, and organic and inorganic composition have also been carried out. The SEM results of the composites showed surface micrographs without microvoids and a good distribution, dispersion and compatibility between the fillers and the EVOH matrix. Concerning the piassava fibers characterization, the results showed that piassava has higher lignin content than cellulose and hemicelluloses, and around 0.7 % of ash with 52 % of silica (Si02). This high concentration of silica is consistent with the SEM analysis of the fiber that showed a large amount of "silica rings" encrusted on their surface.
Desenvolvimento de processo de obtenção de nanopartículas de sílica a partir de resíduo de fonte renovável e incorporação em polímero termoplástico para a fabricação de nanocompósito
2016 - ORTIZ, ANGEL V.
A tecnologia de nanocompósitos é aplicável a uma vasta gama de polímeros termoplásticos e termofixos. A utilização de subprodutos da cana de açúcar tem sido extensivamente estudada como fonte de reforços para os nanocompósitos. O bagaço da cana é largamente utilizado na cogeração de energia e, como resultado da queima deste material, são produzidas milhões de toneladas de cinzas. Para este trabalho, sílica contida nas cinzas do bagaço da cana de açúcar foi extraída por método químico e método térmico. O método térmico se mostrou mais eficiente levando a uma pureza de mais de 93 % em sílica, enquanto o método químico gerou sílica bastante contaminada com cloro e sódio provenientes dos reagentes da extração. As partículas de sílica obtidas foram avaliadas por espalhamento de luz dinâmico (DSL) e apresentaram tamanho médio de 12 μm. Estas partículas foram submetidas à moagem em moinho de bolas e na sequência a tratamento sonoquímico em meio líquido. As partículas de sílica tratadas no processo sonoquímico a 20 kHz, potência de 500 W e 90 minutos tiveram suas dimensões reduzidas a escala nanométrica da ordem de dezenas de nanômetros. A nanossílica obtida foi então incorporada como reforço em polietileno de alta densidade (HDPE). Ensaios mecânicos e termo-mecânicos mostram ganhos de propriedades mecânicas, com exceção da propriedade de resistência ao impacto. O ensaio de deflexão térmica (HDT) mostrou que a incorporação deste reforço no HDPE levou a um pequeno aumento nesta propriedade relação ao HDPE puro. A cristalinidade dos nanocompósitos gerados foi avaliada por meio de calorimetria exploratória diferencial (DSC) e observou-se um decréscimo de cristalinidade do material quando a incorporação de reforço foi de 3%. O material irradiado a 250 kGy com feixe de elétrons mostra ganhos acentuados na principais propriedades do mesmo, principalmente devido ao alto nível de reticulação do HDPE irradiado.
Effects of bio-CaCO3 nanoparticles and graphene nanosheets on properties of PBAT/PLA flexible films treated by ionizing radiation
2016 - REIS, PEDRO R.S.; CARDOSO, ELIZABETH C.L.; LOURENÇO, FELIPE R.; ORTIZ, ANGEL V.; RANGARI, VIJAY K.; MOURA, ESPERIDIANA A.B.
Mechanical, thermal and barrier properties of EVOH/GRAPHENE oxide flexible films treated by electron beam radiation
2016 - SANTANA, JULYANA G.; ORTIZ, ANGEL; AKBULUT, MESHUDE; RANGARI, VIJAY K.; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B.
Ethylene vinyl alcohol (EVOH) copolymers are semicrystalline random copolymers of ethylene and vinyl alcohol that are widely used in the food packaging industry owing to their excellent chemical resistance, high transparency as well as excellent gas barrier properties to oxygen, organic solvents, and food aromas. However, EVOH is very sensitive to moisture and its gas barrier ability deteriorates in high relative humidity conditions. This study presents the preparation of EVOH/Graphene oxide films by twin-screw extrusion and blown film extrusion processing. The preparation of EVOH/Graphene oxide (EVOH/GO) films was carried out in two steps: EVOH with Graphene oxide powder (0-0.5 wt. %) was fed into a co-rotating twin-screw extruder, then the EVOH/GO nanocomposite was transformed into thin films using an extrusion blown film, single screw machine with 25 mm diameter and specimens test samples were obtained. Part of EVOH/GO flexible films were submitted to electron-beam irradiation at 150 and 200 kGy, using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated samples were characterized by mechanical tests, XRD, TG, DSC, FE-SEM and TEM analysis and the correlation between properties was discussed. In addition, the oxygen permeability tests were performed at 23 C, 0 % and 90 % relative humidity using an OX-TRAN (MOCON Inc.). The free volume hole radius of both crystalline (0.201 nm) and amorphous parts (0.258 nm) of EVOH only and EVOH-GO samples were measured by Positron Annihilation Life-Time Spectroscopy. According to the results of the optical transparency measured, the EVOH/GO retaining good transparency films for all graphene oxide percentage added. The EVOH matrix with 0.1-0.4 wt. % graphene oxide content presented better oxygen barrier properties at 0 % relative humidity when compared with neat EVOH flexible films. After irradiation treatment, both, mechanical and oxygen barrier properties were drastically improved. Upon introduction of GO into EVOH matrix a reduction in the free volume hole radius in both parts have been observed indicating the formation of a more compact structure in EVOH/GO nanocomposites. Formation of hydrogen bonding between OH groups of EVOH and polar groups on graphene is assumed to be responsible for the reduction in free volume.
Morphology, optical transparency and oxygen barrier of EVOH/graphene oxide films
2016 - ORTIZ, ANGEL; AKBULUT, MESHUDE; SANTANA, JULYANA G.; RANGARI, VIJAY K.; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA
Food packaging materials require high gas and moisture barrier in other to preserve the quality of the products during storage and handling. Polyolefin materials have been widely used due to their water vapor resistance. Ethylene–vinyl alcohol copolymer (EVOH) is used as a gas barrier layer in packaging products that require high gas barrier. However, EVOH is very sensitive to moisture and its gas barrier ability deteriorates in high relative humidity conditions. In order to overcome the adverse effects of moisture on EVOH film this paper studies the incorporation of small amount of graphene oxide in EVOH by melt processing and evaluates their effects on morphology, optical transparency and oxygen barrier of EVOH film. The EVOH/Graphene oxide (EVOH/GO) film were processed by twin-screw extrusion and extrusion blown film processing. The films was characterized by XRD, FEG-SEM, and UV/VIS analysis. In addition, the oxygen transmission rate (OTR) were performed at 23 C, 0 % and 90 % relative humidity using an OX-TRAN (MOCON Inc.). According to the results of the optical transparency measured, the EVOH/GO retaining good transparency films for all graphene oxide percentage added. The graphene oxide at only 0.1 wt. % into the EVOH matrix drastically improved the oxygen barrier properties of EVOH/GO flexible film in both, 0 % and 90 % of the relative humidity test conditions.
Electron beam irradiation effects on the resistance of packaging materials in the perforation by Lasioderma serricorne
2008 - ALVES, J.N.; ARTHUR, V.; MOURA, E.A.B.; OLIVEIRA, V.M.; ORTIZ, A.V.; POTENZA, M.R.

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