JULYANA GALVÃO SANTANA
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Artigo IPEN-doc 29101 Synergistic effect of e-beam irradiation and graphene oxide incorporation on thermal, mechanical, and barrier properties of poly (ethylene-co-vinyl alcohol) film2022 - SANTANA, JULYANA G.; AKBULUT, MESHUDE; TEMPERINI, MARCIA L.A.; RANGARI, VIJAY K.; GUVEN, OLGUN; MOURA, ESPERIDIANAGraphene and its derivatives, such as graphene oxide (GO), have attracted enormous interest from academia and industry because of its unique electrical, mechanical, and thermal properties, which can lead to enhanced material performance. In the present study, low contents of GO were incorporated into the poly (vinyl alcohol-co-ethylene) (EVOH). First, the GO was prepared by chemical oxidation of graphite employing a modified Hummer's method. The GO content of 0.1–0.3 wt % was incorporated in the EVOH matrix using a twin-screw extruder and extrusion blown film process to prepare flexible films. EVOH/GO film samples were irradiated at 100 kGy, using a 1.5 MeV electron-beam accelerator, at room temperature, in the presence of air. GO was characterized by XRD, ATR-FTIR, FE-SEM, and TEM analysis. XRD patterns of GO show a sharp reflection peak at 2θ = 10° (d001) corresponding to a d-spacing at 8.84 Å, characteristic of GO. The non-irradiated and irradiated samples were characterized by XRD, FEG-SEM, TG, DSC, oxygen transmission rate (OTR), UV/VIS analysis, and tensile tests. EVOH/GO nanocomposite films had an improved oxygen barrier, while also retaining fairly good transparency. As an effect of e-beam irradiation, the thermal, mechanical, and barrier behaviors of the nanocomposite films were even better than non-irradiated film samples, and obviously better than neat EVOH. Thus, the incorporation of low contents of GO followed by e-beam radiation treatment might be an interesting alternative to produce packaging materials based on EVOH with outstanding performance even under very humid conditions.Capítulo IPEN-doc 27622 A comparison between graphene oxide and reduced graphene oxide as reinforcement agents in polypropylene nanocomposite using irradiated polypropylene as compatibilizer2020 - SOARES, CARLOS; SANTANA, JULYANA; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B.Graphene is thematerial with the bestmechanical resistance ever encountered. Various types of studies have been carried out on possible applications. The use as a reinforcement in nanocomposites has shown to be a promising field, but some studies indicate that the graphene oxide (GO) and reduced graphene oxide (RGO) have better results as reinforcement, due to the functional groups,which allowa better adhesion with the matrix. This study analyzes the production of polypropylene (PP) nanocomposite comparing the use of graphene oxide (GO) and reduced graphene oxide (RGO) as fillers and irradiated polypropylene as a coupling agent.Atwin-screw extruder and injection molding machine were used to produce the nanocomposite PP reinforced with 0.2 wt% of GO and RGO by melt blending. The GO and RGO were characterized byXRDanalysis.The nanocomposite sampleswere characterized by XRD, SEM, TG, DSC and mechanical test.Capítulo IPEN-doc 24664 Influence of electron-beam irradiation on the properties of LDPE/EDPM blend foams2018 - SANTANA, JULYANA; SEIXAS, MARCUS V. de S.; RANGARI, VIJAY; VALENZUELA-DIAZ, FRANCISCO; WIEBECK, HELIO; MOURA, ESPERIDIANAClosed-cell polyethylene (PE) foams have been extensively used in many applications such as packaging, transportation, sports, construction, and agriculture because of their variety of properties including light weight, chemical resistance, thermal and electrical insulation. The objective of this study is to evaluate the influence of electron-beam irradiation on the properties of LDPE/EPDM blend foams. The LDPE/EPDM blend (80/20 wt%) were prepared by melt extrusion, using a twin-screw extruder machine. The foam structure of LDPE/EPDM blends was obtained by melt extrusion process, using a special single screw for foaming with 1.5 wt% of foaming agent as blowing agent. The foam samples were irradiated by electron-beam at radiation dose of 25, 50, 75 and 100 kGy and submitted to heating in an oven at 100 °C. The specimen tests samples of irradiated and non-irradiated foams were submitted to mechanical tests, DSC, TG analysis and density measurement.Artigo IPEN-doc 22627 Preparation of EVOH/graphene oxide by blown film extrusion – correlation between film properties and graphene oxide addition2016 - BARREIRA, DAILI A.S.; SANTANA, JULYANA G.; LAZARO, LOURDES Y.; RUIZ, JESUS G.; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B.This study reports the preparation of EVOH films reinforced with graphene oxide 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. The purpose of this study was to evaluate the correlation between mechanical properties and thermal stability of EVOH/GO films and the amount of graphene oxide added to the EVOH matrix. Tensile tests were conducted using an INSTRON Testing Machine. DSC and TG analysis were used for investigate the thermal stability of EVOH/Graphene oxide films. DSC analysis results showed that melting temperature (Tm), melting enthalpy (Hm) and consequently the degree of crystallinity (Xc) of neat EVOH increased with the incorporation of the 0.1 and 0.5 wt. % of GO. TG of the composites showed a great difference in weight loss and in the onset degradation temperature when compared with the neat EVOH. The more important change was observed for EVOH/GO with 0.2 wt. % GO content that presented an increase of the onset degradation temperature. A significant enhancement of the tensile strength at break of EVOH/GO flexible film without important effects on the elongation at break were also observed, except for EVOH/GO with 0.2 wt. % GO content that presented an important increase in both, tensile strength and elongation at break. It can be concluded that the addition of GO is an effective means to improve the EVOH flexible films properties and led to the obtaining of packaging materials with superior properties suitable for several industrial applications.