RENE RAMOS DE OLIVEIRA

RENE RAMOS DE OLIVEIRA

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Production and characterization of PBAT reinforced with clay and graphene oxide nanosheets
2020 - COSTA, ROBSON S.; ARAUJO, DANIELLE G.; ANDRADE, MARCIO S. de; OLIVEIRA, RENE R.; RANGARI, VIJAYA; MOURA, ESPERIDIANA A.B.; DIAS, FRANCISCO V.
The poly (butylene adipate-co-terephthalate) (PBAT), a biodegradable polymer, is among the most promising materials to be considered as environmentally friendly high performance biodegradable plastics. However, the mechanical properties of PBAT are not the best for several applications. According to the literature, the properties of the biodegradable polymer can be improved by addition of a small amount of nanofillers, such as clay, silica, and graphene. The objective of this study is to compare the effect of the addition of Cloisite clay and graphene oxide (GO) on the properties of flexible films based on PBAT matrix. The composite films based on PBAT with addition of Cloisite (2.0 wt%) and PBAT composite films with addition of Cloisite and GO (0.1–0.2 wt%) were prepared by extrusion, using a twin-screw extruder and a flat die single extruder. The effects of the addition of Cloisite clay and graphene oxide on mechanical and thermal properties of films were evaluated by mechanical and water absorption tests, FE-SEM, XRD, and Raman analysis.
Mechanical and morphological properties of hybrid composites based on recycled LDPE/EVA blend reinforced with clay and babassu fiber residues
2020 - TAMURA, CAROLINE S.; ARANTES, MARIANA; CARMO, KARINA H.S.; SANTOS, BIANCA S.; OLIVEIRA, RENE R.; MOURA, ESPERIDIANA A.B.
Over the years the consumption of plastic products made of conventional polymers has produced a large amount of waste which has led to disposal problems worldwide. Among the alternatives to minimize these problems are reuse and recycling practices. Then, the recycling of plastic and the use of recycled materials to produce new materials reinforced with nanoparticles from natural resources can be an alternative to reduce inappropriate waste disposal. The objective of this study is to investigate the effects of the addition of clay and non-treated babassu fiber residues on the mechanical and morphological properties of composite based on recycled LDPE/EVA blend. Composite materials containing 1–3 wt% of babassu residues and 1 wt% of clay were prepared using a twin-screw extruder machine and flat die single extrusion process, in order to prepare hybrid composites sheets. The sheets prepared by recycled LDPE/EVA blend and its composites were characterized by tensile tests, XRD, and FE-SEM analysis and the correlation between properties was discussed.
Investigation on mechanical and thermal behaviours of PBAT/PLA blend reinforced with reduced graphene oxide nanosheets
2020 - BARTOLOMEI, MARCIO R.X.; CARMO, KARINA H.S.; SANTOS, BIANCA S.; BARTOLOMEI, SUELLEN S.; OLIVEIRA, RENE R.; MOURA, ESPERIDIANA A.B.
The aim of this study was to process and investigate the changes in the mechanical and morphological properties of the biodegradable nanocomposites based on polybutylene adipate-co-terephthalate (PBAT)/poly(lactic acid) (PLA) blend (PBAT/PLA blend) due to the incorporation of reduced graphene oxide (RGO) nanosheets. The biodegradable polymeric nanocomposites were prepared by melting extrusion process using a twin-screw extruder machine. The influence of the RGO nanosheets incorporation on mechanical and thermal properties of PBAT/PLA blend was investigated by tensile Thermogravimetric (TG), X-Ray diffraction (XRD), differential scanning calorimetry (DSC), and tensile test analysis. Results showed that incorporation of the small amount ofRGO(0.1wt.%) ofRGOnanosheets in the blend matrix of PBAT/PLA resulted in an important gain of mechanical properties of the blend. This result indicates that a very small amount of RGO nanosheets addition in the PBAT/PLA can lead to obtaining materials with superior properties suitable for several industrial applications.
Influence of the reduced graphene oxide incorporation on properties of acrylonitrile butadiene styrene (ABS)
2020 - SANTOS, BIANCA S.; INACIO, ANDRE L.N.; BARTOLOMEI, SUELLEN S.; SILVA, TAISE B.S.; CARMO, KARINA L.S.; OLIVEIRA, RENE R.; MOURA, ESPERIDIANA A.B.
The purpose of this study was to evaluate the influence of incorporation of the reduced graphene oxide on properties of acrylonitrile butadiene styrene (ABS). The incorporation of 0.5 and 1.5 wt% of RGO into ABS matrix was carried out by melting extrusion process using a twin-screw extruder and injection molding machine. The properties of ABS/RGO nanocomposite samples were investigated by tensile and impact Izod tests, FE-SEM, and XRD analysis. The results showed that the incorporation of small amount of RGO into ABS matrix led to obtaining of polymeric nanocomposite with superior mechanical properties when compared with original properties of ABS matrix.
Improvement properties of polypropylene by graphene oxide incorporation
2020 - TATEI, TATIANE Y.; FONTES, ERIC H.; MOREIRA, RENAN P.; DIAS, FRANCISCO V.; OLIVEIRA, RENE R.; RANGARI, VIJAYA; MOURA, ESPERIDIANA A.B.
Due to the remarkable properties of graphene oxide (GO) and its possibility of functionalization,GOhas been used in many applications such as nanocomposites. GO nanosheets have been shown to improve the properties of the polypropylene (PP) matrix, for instance, its strength, gas barrier, thermal, and electrical conductivity. As PP has relatively low cost and varied applications, this work aims to study the changes in its thermal, morphological, and mechanical properties, due to the incorporation of GO in the PP matrix. GO was synthesized from graphite by a modified Hummers method. The nanocomposites PP/GO with 0.1, 0.2, and 0.3 wt% of GO in the PP matrix were obtained using a twin-screw extruder and an injection molding machine via a melt blending process. The nanocomposites PP/GO were characterized by FE-SEM and Izod impact test. In addition, the GO nanosheets were also characterized by Raman spectroscopy, ATR-FTIR, FE-SEM, and XRD, therewith correlation between properties was discussed.
Development of biocomposite materials from biodegradable polymer and bio-hydroxyapatite derived from eggshells for biomedical applications
2019 - REIS, PEDRO R.S.; SANTANA, JULYANA G.; OLIVEIRA, RENE R.; RANGARI, VIJAYA K.; LOURENÇO, FELIPE R.; MOURA, ESPERIDIANA A.B.
Nowadays, significant advances have been made in the development of biodegradable polymeric materials for biomedical applications. This study aims to prepare and characterize composite materials based on PLA/PBAT, a biodegradable polymer blend, reinforced with bio-hydroxyapatite (bio-HAp). First, bio-HAp was obtained from eggshell residues by the wet precipitation method. PLA/PBAT blend with 1.5 wt% of bio-HAp was prepared by melt extrusion and injection molding process. Part of composite samples was irradiated with gamma radiation dose of 25 kGy, at room temperature and presence of air. The effects of the bio-HAp addition into the biodegradable blend were investigated by mechanical tests, XRD, DSC, FESEM, and cytotoxicity “in vitro” analysis and the correlation between the properties was discussed. In addition, the microbiological tests were carried out at irradiated and non-irradiated composite samples in order to evaluate the efficiency of the radiation dose of 25 kGy at composite materials sterilization.
Comparative study of the use of rice husk ashes and graphite as fillers in polypropylene matrix composites
2019 - MONTEIRO, ALEX S.; BARREIRA, DAILI A.S.; BARTOLOMEI, SUELLEN S.; OLIVEIRA, RENE R.; MOURA, ESPERIDIANA A.B. de
In recent years, carbonaceous materials have been widely studied for polymer composite applications due to its capability to improve the engineering properties of the polymeric matrix. Among various carbonaceous fillers, carbon nanotube, graphene, and graphite promise to be a suitable reinforcement of polymers. Rice husk ash (RHA), a large residue rich in carbon and silica produced by the burning of rice husk offers also an immense potential as a carbonaceous filler for polymer composites on account of its lowcost, lowdensity, high strength and elastic modulus, no health risks, and renewability. This work aims at studying the effects of RHA and graphite as fillers in polypropylene (PP) matrix composites. The composites PP/RHA and PP/graphite were produced by melting extrusion process. The materials obtained were subjected to mechanical tests, XRD, TG, and FEG-SEM analyses. Comparison studies between neat PP properties and its composites were carried out.
An investigation of mechanical and thermal properties of polypropylene reinforced with different clays
2019 - MONTEIRO, ALEX S.; BARREIRA, DAILI A.S.; SILVA, JAQUELINE S.; OLIVEIRA, RENE R.; VALENZUELA-DIAZ, FRANCISCO R.; MOURA, ESPERIDIANA A.B.
Nowadays, environmental awareness and an increasing concern with the greenhouse effect have increased the interest in composite materials containing at least one of the components from natural origin. Natural clays seem to be a good alternative because they are environmentally acceptable, naturally abundant minerals, and due to their ability to intercalate and exfoliate in the polymer matrix led to an improvement in mechanical, thermal and barrier properties, compared to the neat polymer. This work presents an investigation of the effects of incorporation of two different clays on mechanical and thermal properties of polypropylene (PP) matrix. PP with 1.5–3.0 wt% of the Cloisite® (commercial clay), and light green clay (noncommercial Brazilian clay), was prepared by melt extrusion process. The neat PP and its nanocomposites were characterized by mechanical tests, SEM, DSC, TGA and XRD analyses. In addition, clay characterization by XRD has also been carried out.
Study of flexible films prepared from PLA/PBAT blend and PLA E-beam irradiated as compatibilizing agent
2017 - CARDOSO, ELIZABETH C.L.; OLIVEIRA, RENE R.; MACHADO, GLAUSON A.F.; MOURA, ESPERIDIANA A.B.
Plastics global annual production exceeds 250 million tons and more than 40% of the total plastic production is used as packaging materials. In recent years polymeric materials derived from biomass have received great attention due to scarce petroleum resources and environmental concerns. PLA is one of the most extensively studied bio-based and bio-compostable aliphatic polyesters; nevertheless, high brittleness and low toughness limits its application. Blending PLA with PBAT (Poly(butylene adipate-co-terephthalate)), an aliphatic-aromatic copolyester, was the solution found due to its high toughness and biodegradability. Differences between PLA and PBAT solubility parameter values lead to the formation of immiscible blends as well as reduction in their mechanical performance besides a poor morphology; so, 5% of pre-irradiated PLA and a previous compatibilized PLA/PBAT (EcovioTM) were added to PLA/PBAT blends in order to improve miscibility phases. Investigations were accomplished on phase morphology (SEM), mechanical properties, thermal behavior and X-ray diffractions (XRD).
Polymer blend based on recycled polyethylene and ethylene vinyl acetate copolymers reinforced with natural fibers from agricultural wastes
2017 - COIADO, RENATA D.S.; LAZO, GISELE D.; OLIVEIRA, RENE R.; RODRIGUES, RITA C.L.B.; MOURA, ESPERIDIANA A.B.
Agricultural residues, which are produced with large quantities annually throughout the world, may be used as reinforcement plastic to replace the wood and produce particleboard for application in the development of low cost construction elements and reduced environmental impact. The main aims of this study was to investigate the effects of agricultural wastes and glass residues addition on the properties of recycled-HDPE/EVA blend for use in particleboard manufacture. The recycled-HDPE/EVA blend reinforced with corncob fiber (15 wt%), coffee parchment (15 wt%) and glass residues (1 wt%) were processed by melt extrusion, using a twin screw extruder and injection molding machine to obtain specimen test samples. The samples were characterized by mechanical test, XRD, TG, DSC, and FE-SEM analysis to understand the nature of interaction between the fillers reinforcement and recycled-HDPE/EVA blend matrix and their properties were discussed.