RENE RAMOS DE OLIVEIRA

RENE RAMOS DE OLIVEIRA

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Effectiveness of modified lignin on poly(butylene adipateco-terephthalate)/poly(lactic acid) mulch film performance
2023 - BARROS, JANETTY J.P.; OLIVEIRA, RENE R.; LUNA, CARLOS B.B.; WELLEN, RENATE M.R.; MOURA, ESPERIDIANA A.B.
In this work, the biodegradable poly(butylene adipate-co-terephthalate) (PBAT)/ poly(lactic acid) (PLA) blend (ECOVIO®) and lignin, a renewable and biodegradable natural polymer with high UV absorption and modified by gamma radiation were used to produce agriculture mulch films. Lignin was gammairradiated at 30 and 60 kGy. The irradiated and non-irradiated lignin content of 2 wt% was incorporated into PBAT/PLA blend matrix using a twin-screw extruder and extrusion blown film to prepare flexible films. PBAT/PLA/LIGNIN films were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), tensile tests, contact angle, and UV–Vis analysis. FTIR spectra showed partial miscibility between PBAT/PLA and lignin, being intensified in irradiated lignin compounds. The DSC and XRD results confirmed that the degree of crystallinity of the blends was not significantly influenced by lignin addition. FE-SEM images showed better dispersion and miscibility in PBAT/PLA/Irradiated lignin. Miscibility improvement provided by irradiated lignin promoted better mechanical properties, mainly with lignin irradiated at 60 kGy. PBAT/PLA/LIGNIN films containing 2 wt% showed excellent UV-barrier property and greater hydrophobicity. Summing up, incorporation of low contents of irradiated lignin could be an interesting alternative to produce biodegradable UV-blocking agriculture mulch films.
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.
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.
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.
Comparative study of the effects of cellulose nanowhiskers and microcrystalline cellulose addition as reinforcement in flexible films based on biopolymer blends
2016 - PAIVA, DOUGLAS A.; OLIVEIRA, RENE R.; MAIA, WILSON da S.; AUAD, MARIA L.; RANGARI, VIJAYA K.; MOURA, ESPERIDIANA A.B.
The objective of this study is to compare the effects of the addition of cellulose nanowhiskers and microcrystalline cellulose on properties of flexible films based on biodegradablepolymer blends. Composite films containing 1 wt. % of microcrystalline cellulose and 1-2 wt.% of cellulose nanowhiskers were prepared by melt extrusion, using a twin screw extruder machine and blown extrusion process. The effects of the addition of cellulose nanowhiskers and microcrystalline cellulose on mechanical and thermal properties of biocomposite films were investigated by tensile tests, XRD, TG, DSC and FE-SEM analysis and the correlation between properties was discussed.
Study of flexible films prepared from PBAT/PLA blends reinforced with bio-CaCO3
2016 - CARDOSO, ELIZABETH C.L.; BUENO, NELSON R.; OLIVEIRA, RENE R.; 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. The most widely used materials include polyethylene (PE) and polypropylene (PP), among others. However, petrochemical-based conventional packaging materials are non-biodegradable and cause serious environmental problems. Poly (lactic acid) (PLA), a linear aliphatic polymer is known as a biodegradable thermoplastic polymer with widely potential applications. However, its high brittleness and low toughness limits its application; blending PLA with PBAT (Poly (butylene adipate-co-terepthalate), an aliphatic-aromatic copolyester, was the solution found due to its high toughness and biodegradability. Nevertheless, differences between PLA and PBAT solubility parameter values lead to the formation of immiscible blends as well as reduction in their mechanical performance. CaCO3 from avian eggshells, when added in PLA / PBAT composites imparts optimization of mechanicals properties due to its characteristic as reinforcing filler. This study aims to evaluate the effects of PLA addition in PBAT/PLA blends especially concerned to mechanical and thermal properties of PLA / PBAT / CaCO3 flexible films. Composites were prepared by melt processing, using a twin-screw extruder (L/D - 25). Before blown film processing, the composites were cooled down for a better dimensional stability, pelletized and dried at 60 ± 2 ºC for 24 h. The mechanical and thermal properties of obtained films were investigated by tensile tests, DSC and TG / DTG. In addition, the morphology of blends and composites were also evaluated by XRD and SEM analyses. The results showed important increase in crystallinity and tensile strength at break of flexible films without severe loss in elongation percentage, due to CaCO3 additional in PBAT / PLA blend with higher PLA contents.
Development of bio-based foams prepared from PBAT/PLA reinforced with biio-calcium carbonate compatibilized by electron beam radiation
2016 - CARDOSO, ELIZABETH C.L.; SEIXAS, MARCUS V.S.; WIEBECK, HELIO; OLIVEIRA, RENE R.; MACHADO, GLAUSON A.F.; MOURA, ESPERIDIANA A.B.