Navegação por autor "GUVEN, OLGUN"

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  • IPEN-DOC 22428

    BARSBAY, MURAT; GUVEN, OLGUN; KODAMA, YASKO . Amine functionalization of cellulose surface grafted with glycidyl methacrylate by gamma-initiated RAFT polymerization. Radiation Physics and Chemistry, v. 124, p. 140-144, 2016.

    Palavras-Chave: amines; cellulose; surfaces; grafts; methacrylates; polymerization; filters; paper; spectroscopy; scanning electron microscopy

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  • IPEN-DOC 27622

    SOARES, CARLOS ; SANTANA, JULYANA ; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . A comparison between graphene oxide and reduced graphene oxide as reinforcement agents in polypropylene nanocomposite using irradiated polypropylene as compatibilizer. In: LI, JIAN (Ed.); ZHANG, MINGMING (Ed.); LI, BOWEN (Ed.); MONTEIRO, SERGIO N. (Ed.); IKHMAYIES, SHADIA (Ed.); KALAY, YUNUS E. (Ed.); HWANG, JIANN-YANG (Ed.); ESCOBEDO-DIAZ, JUAN P. (Ed.); CARPENTER, JOHN S. (Ed.); BROWN, ANDREW D. (Ed.). Characterization of Minerals, Metals, and Materials. Cham, CZ, Switzerland: Springer Nature Switzerland AG, 2020. p. 385-394, (The Minerals, Metals & Materials Series). DOI: 10.1007/978-3-030-36628-5_36

    Abstract: 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.

    Palavras-Chave: graphene; oxides; polypropylene; nanocomposites; gamma radiation; stresses; tensile properties

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  • IPEN-DOC 24663

    ARANTES, MARIANA M. ; SANTANA, JULYANA ; VALENZUELA-DIAZ, F.R.; RANGARI, VIJAY K.; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Development and characterization of recycled-HDPE/EVA foam reinforced with babassu coconut epicarp fiber residues. In: LI, BOWEN (Ed.); LI, JIAN (Ed.); IKHMAYIES, SHADIA (Ed.); ZHANG, MINGMING (Ed.); KALAY, YUNUS E. (Ed.); CARPENTER, JOHN S. (Ed.); HWANG, JIANN-YANG (Ed.); MONTEIRO, SERGIO N. (Ed.); FIRRAO, DONATO (Ed.); BROWN, ANDREW (Ed.); BAI, CHENGUANG (Ed.); PENG, ZHIWEI (Ed.); ESCOBEDO-DIAZ, JUAN P. (Ed.); GOSWAMI, RAMASIS (Ed.); KIM, JEONGGUK (Ed.). Characterization of Minerals, Metals, and Materials. TMS. Cham, CZ, Switzerland: Springer International Publishing AG, 2018. p. 497-506, (The Minerals, Metals & Materials Series). DOI: 10.1007/978-3-319-72484-3_52

    Abstract: Nowadays, the development of polymeric materials reinforced with residues of vegetal fibers is becoming popular for application in different segments, from the automotive to the civil construction and furniture industry. Vegetal fiber residues may be used as reinforcement of the recycled polymer materials, for instance, to produce foams to packaging or to thermal and acoustic isolation for green building application. This work is focused on the development and characterization of recycled-HDPE/EVA foam reinforced with fiber residues from babassu coconut epicarp. Firstly, composites based on recycled-HDPE/EVA blend reinforced with babassu coconut fiber were obtained by melting extrusion process. The composites were then extruded in a special single screw for foaming. The foam samples were submitted to mechanical tests, density measurement, DSC, TG, and FE-SEM analysis.

    Palavras-Chave: coconut palms; coconuts; fibers; polyethylenes; polymerization; polyvinyls; recycling

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  • IPEN-DOC 24845

    SANTANA, JULYANA G. ; SEIXAS, M.V. de S. ; ARANTES, MARIANA ; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Effects on Clay addition on properties of LDPE flexible films. In: PAN AMERICAN CONGRESS OF NANOTECHNOLOGY, 1st, 27-30 de novembro, 2017, Guarujá, SP. Abstract... 2017.

    Abstract: Studies have indicated that the addition of nanoparticles in flexible films improves performance flexible packaging, leading to better mechanical, thermal and barrier properties. Clay is an abundant mineral, inexpensive, easy to process, and provide considerable enhancements on the properties of polymers. Titanium dioxide (TiO 2 ) is widely used for its efficiency in scattering visible light, and imparting whiteness, brightness, and high opacity when incorporated into a plastic formulation. Low density polyethylene (LDPE) is generally used as a packaging material due to its good resistance, easy processing, low cost and high hardness. The objective of this study was to evaluate the effects of clay and TiO 2 nanoparticles addition on the properties of LDPE flexible films. LDPE with 1 wt % of TiO 2 addition and 1-3 wt. % of green Brazilian Clay, from Cubati, Pb, Brazil were prepared by melt extrusion process, using a twin-screw extruder Haake Rheomex P332 with 16 mm and L/D = 25, from Thermo Scientific. Then the LDPE/Clay nanocomposite was transformed into thin films using an extrusion blown film, single screw machine with 25 mm diameter and specimen test samples were obtained. The specimen samples were characterized by mechanical tests, UV-VIS, DSC, TG and FE-SEM analysis.

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  • IPEN-DOC 20250

    BARSBAY, MURAT; KODAMA, YASKO ; GUVEN, OLGUN. Functionalization of cellulose with epoxy groups via 'gamma'-initiated RAFT-mediated grafting of glycidyl methacrylate. Cellulose, v. 21, n. 6, p. 4067-4079, 2014.

    Palavras-Chave: graft polymers; cellulose; epoxides; methacrylates; gamma radiation; polymerization

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  • IPEN-DOC 29697

    COLOMBO, MARIA A.S. ; DIAZ, FRANCISCO R.V.; KODALI, DEEPA; RANGARI, VIJAYA; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Influence of reinforcing efficiency of clay on the mechanical properties of poly(butylene terephthalate) nanocomposite. Ceramics, v. 6, n. 1, p. 58-73, 2023. DOI: 10.3390/ceramics6010005

    Abstract: In contrast to traditional fillers, clay, in particular, natural smectite clay, represents an environmentally significant alternative to improve the properties of polymers. Compared to conventional nanofillers, smectite clay can effectively enhance the physical and mechanical properties of polymer nanocomposites with a relatively small amount of addition (<5 wt%). The present study focuses on investigating the reinforcing efficiency of different amounts (up to 5 wt%) of a natural Brazilian smectite clay modified (MBClay) on the mechanical properties of poly(butylene terephthalate) (PBT) nanocomposites and also evaluates the correlation between MBClay addition and the mechanical and thermal behaviors of the PBT/MBClay nanocomposites. Natural Brazilian clay modified by the addition of quaternary salt and sodium carbonate (MBClay) was infused into the PBT polymer by melt extrusion using a twin-screw extruder. It was found that the best properties for PBT were obtained at 3.7 wt% of modified BClay. Tensile strength at break exhibited increased by about 60%, flexural strength increased by 24%, and flexural modulus increased by 17%. In addition, an increase in the crystallinity percentage of PBT/BClay nanocomposite was confirmed by DSC and XRD analysis, and a gain of about 45% in HDT was successfully achieved due to the incorporation of 3.7 wt% of MBClay

    Palavras-Chave: nanocomposites; clays; polymers; matrix materials; mechanical properties; morphology

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  • IPEN-DOC 25762

    BARTOLOMEI, SUELLEN S. ; SANTANA, JULYANA G. ; DIAZ, FRANCISCO R.V.; KAVAKLI, PINAR A.; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Investigation of the effect of titanium dioxide and clay grafted with glycidyl methacrylate by gamma radiation on the properties of EVA flexible films. Radiation Physics and Chemistry, v. 169, p. 1-9, 2020. DOI: 10.1016/j.radphyschem.2018.08.022

    Abstract: Many studies report that nanocomposites obtained by dispersion of a small amount nanofiller into the polymer have remarkable improvements achieved in the mechanical and physical properties. However, in order to achieve this great improvement in properties, it is necessary that the nanofillers be dispersed homogeneously into the polymeric matrix. Often this dispersion is difficult to achieve due to the high interfacial energy of the nanoparticles present. This study reports the effect of gamma irradiation induced graft of glycidyl methacrylate (GMA) onto the surface of TiO2 and Clay nanofillers to improve their dispersion into the EVA matrix. The physical and mechanical properties of Ethylene-vinyl acetate copolymer (EVA) flexible films with these nanoparticles were studied. EVA nanocomposite with adding of the different amount of TiO2 and modified montmorillonite clay grafted and un-grafted with glycidyl methacrylate (GMA) using gamma irradiation have been prepared by melt extrusion. The nanocomposite flexible films were produced using a flat die extrusion process. The PGMA-grafted nanofillers were characterized by XRD and TEM analysis. The flexible films were characterized by Tensile tests, ATR–FTIR, UV–VIS, XRD, TG, and FE-SEM analysis to understand the nature of the interaction between the nanofillers and EVA matrix. The results showed that the addition of PGMA-grafted TiO2 and Clay nanofillers into EVA matrix improved the bonding between the nanofillers and matrix. It was also found that the PGMA-grafted nanofillers could be well dispersed into an EVA matrix in contrast to that of un-grafted. The tensile strength and modulus of the resulting EVA/TiO2-PGMA enhanced in comparison to that of un-grafted TiO2. The EVA/Clay-PGMA had slightly decreased tensile strength comparable to that of EVA/Clay but had considerably improved elastic modulus. In addition, the flexible films based on TiO2 exhibited high UV–Vis light absorption with energy gap shifted to the visible region. The results demonstrated that TiO2 and Clay nanofillers grafted with GMA by gamma radiation can be used to prepare EVA flexible films with improved bonding between the nanofillers and matrix and, consequently, enhanced properties for food and cosmetic packaging application.

    Palavras-Chave: dispersions; films; gamma radiation; irradiation; methacrylates; nanocomposites; physical properties; polymerization; titanium oxides; x-ray diffraction

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  • IPEN-DOC 23584

    SANTANA, JULYANA G. ; ORTIZ, ANGEL ; AKBULUT, MESHUDE; RANGARI, VIJAY K.; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Mechanical, thermal and barrier properties of EVOH/GRAPHENE oxide flexible films treated by electron beam radiation. In: MEETING OF IONIZING RADIATION AND POLYMERS SYMPOSIUM, 12th, September 25-30, 2016, Peninsula of Giens, France. Abstract... 2016.

    Abstract: 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.

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  • IPEN-DOC 25004

    SANTANA, JULYANA G. ; ORTIZ, ANGEL ; OLIVEIRA, RENE R. ; RANGARI, VIJAY K.; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Mechanical, thermal, morphology and barrier properties of flexible film based on polyethylene-ethylene vinyl alcohol blend reinforced with graphene oxide. In: IKHMAYIES, SHADIA (Ed.); LI, BOWEN (Ed.); CARPENTER, JOHN S. (Ed.); LI, JIAN (Ed.); HWANG, JIANN-YANG (Ed.); MONTEIRO, SERGIO N. (Ed.); FIRRAO, DONATO (Ed.); ZHANG, MINGMING (Ed.); PENG, ZHIWEI (Ed.); ESCOBEDO-DIAZ, JUAN P. (Ed.); BAI, CHENGUANG (Ed.); KALAY, YUNUS E. (Ed.); GOSWAMI, RAMASIS (Ed.); KIM, JEONGGUK (Ed.). Characterization of Minerals, Metals, and Materials. Gewerbestrasse, Switzerland: Springer International Publishing AG., 2017. p. 49-57, (The Minerals, Metals & Materials Series). DOI: 10.1007/978-3-319-51382-9_7

    Abstract: 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.).

    Palavras-Chave: packaging; food industry; alcohols; ethylene; copolymers

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  • IPEN-DOC 22626

    ORTIZ, ANGEL ; AKBULUT, MESHUDE; SANTANA, JULYANA G. ; RANGARI, VIJAY K.; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA . Morphology, optical transparency and oxygen barrier of EVOH/graphene oxide films. In: BRAZILIAN CONFERENCE ON COMPOSITE MATERIALS, 3rd, August 28-31, 2016, Gramado, RS. Proceedings... 2016.

    Abstract: 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.

    Palavras-Chave: packaging; graphene; ethylene; alcohols; copolymers; morphology

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  • IPEN-DOC 29892

    COSTA, FERNANDA A.T. da ; PARRA, DUCLERC F. ; CARDOSO, ELISABETH C.L. ; GUVEN, OLGUN. PLA, PBAT, Cellulose Nanocrystals (CNCs), and their blends: biodegradation, compatibilization, and nanoparticle interactions. Journal of Polymers and the Environment, v. 31, n. 11, p. 4662–4690, 2023. DOI: 10.1007/s10924-023-02899-7

    Abstract: PLA/PBAT (Poly (lactic acid)/Poly (butylene adipate-co-terephthalate)) blend is a biodegradable material commonly considered a potential alternative to polymeric products from petroleum sources. PLA is intrinsically brittle, endowed with a low elongation at break and poor impact strength that restricts its use for some applications while PBAT has high ductility, heat resistance, and impact resistance. However, PLA associated with PBAT results in an incompatible blend, due to poor interfacial adhesion. The compatibilization of PLA/PBAT can be improved through physical and chemical interaction between the components, and with exposure to ionizing radiation. Cellulose is the most abundant biodegradable polymer available and is considered the potential material to be used as reinforcement in sustainable composite materials, as well as nanocellulose while an alternative to synthetic nanoparticles. This review describes the state of the art of polymer blends of PBAT and PLA, in terms of manufacturability, compatibilization, biodegradation, radiation processing, and cellulose nanocrystal reinforcement.

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  • IPEN-DOC 20189

    KODAMA, YASKO ; BARSBAY, MURAT; GUVEN, OLGUN. Poly(2-hydroxyethyl methacrylate) (PHEMA) grafted polyethylene/polypropylene (PE/PP) nonwoven fabric by 'gmma'-initiation: synthesis, characterization and benefits of RAFT mediation. Radiation Physics and Chemistry, v. 105, p. 31-38, 2014.

    Palavras-Chave: polyethylenes; polypropylene; graft polymers; methacrylates; gamma radiation; synthesis; polymerization

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  • IPEN-DOC 22627

    BARREIRA, DAILI A.S. ; SANTANA, JULYANA G. ; LAZARO, LOURDES Y.; RUIZ, JESUS G.; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Preparation of EVOH/graphene oxide by blown film extrusion – correlation between film properties and graphene oxide addition. In: BRAZILIAN CONFERENCE ON COMPOSITE MATERIALS, 3rd, August 28-31, 2016, Gramado, RS. Proceedings... 2016.

    Abstract: 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.

    Palavras-Chave: graphene; calorimetry; differential thermal analysis; tensile properties; thermal gravimetric analysis

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  • IPEN-DOC 24940

    SANTANA, JULYANA G. ; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Propriedades térmicas e mecânicas de filmes flexíveis de polietileno e copolímero de etileno e álcool vinílico reforçados com óxido de grafeno / Thermal and mechanical properties of flexible films of polyethylene and ethylene vinyl alcohol reinforced with graphene oxide. In: CONGRESSO BRASILEIRO DE POLIMEROS, 14., 22-26 de outubro, 2017, Águas de Lindóia, SP. Anais... 2017. p. 1797-1802.

    Abstract: Os copolímeros de etileno e álcool vinílico (EVOH) são uma família de resinas com excelentes propriedades de barreira a gás de grande importância para a indústria de embalagens para alimentos, o polietileno de alta densidade (HDPE) um polímero hidrofóbico que em mistura com o EVOH, agrega melhores propriedades de barreira e mecânicas a embalagem final. O objetivo deste trabalho foi estudar os efeitos da adição de óxido de grafeno (GO) nas propriedades de filmes flexíveis preparados a partir de uma blenda HDPE e EVOH (HDPE/EVOH). Que foram processados, utilizando-se uma extrusora dupla rosca corrotante, e posteriormente os materiais processados foram alimentados a uma extrusora balão de laboratório para a obtenção dos filmes flexíveis. Os filmes flexíveis foram caracterizados por meio das análises de DSC, TG, MEV e ensaios de tração e a correlação entre as suas propriedades foi discutida.

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  • IPEN-DOC 20073

    KODAMA, YASKO ; BARSBAY, MURAT; GUVEN, OLGUN. Radiation-induced and RAFT-mediated grafting of poly(hydroxyethyl methacrylate) (PHEMA) from cellulose surfaces. Radiation Physics and Chemistry, v. 94, p. 98-104, 2014.

    Palavras-Chave: ; graft polymers; methacrylates; cellulose; x radiation

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  • IPEN-DOC 23508

    GUVEN, OLGUN; MONTEIRO, SERGIO N.; MOURA, ESPERIDIANA A.B. ; DRELICH, JAROSLAW W.. Re-emerging field of lignocellulosic fiber – polymer composites and ionizing radiation technology in their formulation. Polymer Reviews, v. 56, n. 4, p. 1-35, 2016. DOI: 10.1080/15583724.2016.1176037

    Abstract: Natural cellulose-based fibers offer low cost, low density composite reinforcement with good strength and stiffness. Because of their annual renewability and biodegradability, natural fibers have materialized as environmentally-friendly alternatives to synthetic fibers in the last two decades. They are replacing synthetic materials in some traditional composites in industrial manufacturing sectors such as automotive, construction, furniture, and other consumer goods. In this work, the use of lignocellulosic fibers in green materials engineering, particularly their application as polymeric composite reinforcement and surface treatment via ionizing radiation are reviewed. Because these cellulose-based materials are intrinsically hydrophilic, they require surface modification to improve their affinity for hydrophobic polymeric matrices, which enhances the strength, durability, and service lifetime of the resulting lignocellulosic fiber-polymer composites. In spite of a long history of using chemical methods in the modification of material surfaces, including the surface of lignocellulosic fibers, recent research leans instead towards application of ionizing radiation. Ionizing radiation methods are considered superior to chemical methods, as they are viewed as clean, energy saving, and environmentally friendly. Recent applications of controlled ionizing radiation doses in the formulation of natural fiber –reinforced polymeric composites resulted in products with enhanced fiberpolymer interfacial bonding without affecting the inner structure of lignocellulosic fibers. These applications are critically reviewed in this contribution.

    Palavras-Chave: gamma radiation; composite materials; ionizing radiations; cellulose; fibers; plants

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  • IPEN-DOC 24834

    LODIS, ALINE M. ; SEIXAS, M.V. de S. ; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA A.B. . Structure and thermal/mechanical properties of poly (ϵ‐caprolactone)‐clay blend: synthesis and characterization of eva/clay flexible films treated by electron beam radiation. In: PAN AMERICAN CONGRESS OF NANOTECHNOLOGY, 1st, 27-30 de novembro, 2017, Guarujá, SP. Abstract... 2017.

    Abstract: In the area of nanotechnology, polymer matrix based on nanocomposites have generated a significant amount of attention in the recent literature. The achieved results were at least initially viewed as unexpected (‘‘nano-effect’’) offering improved properties over that expected from thermal and mechanics predictions. This work presents the synthesis and characterization of EVA/Clay flexible films treated by electron beam radiation. EVA with 0.5 -3 wt.% of green Brazilian Clay addition were prepared by melt extrusion process, using a twin-screw extruder Haake Rheomex P332 with 16 mm and L/D = 25, from Thermo Scientific. Then, EVA/Clay nanocomposite was transformed into flexible films using a single-screw extruder with 25 mm diameter equipped with a flat die (laboratory line) and specimen test samples were obtained. Part of flexible film samples was submitted at electron beam radiation dose range 25-100 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. The irradiated and non-irradiated samples were submitted to mechanical tests, XRD, UV-VIS, DSC, TG and FE-SEM analysis. The results showed significant changes in mechanical and thermal properties of EVA/CLAY flexible film due to clay addition and electron-beam irradiation. These results showed that it is possible to get interesting property in EVA flexible films by clay addition and electron-beam radiation treatment

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  • IPEN-DOC 29101

    SANTANA, JULYANA G. ; AKBULUT, MESHUDE; TEMPERINI, MARCIA L.A.; RANGARI, VIJAY K.; GUVEN, OLGUN; MOURA, ESPERIDIANA . Synergistic effect of e-beam irradiation and graphene oxide incorporation on thermal, mechanical, and barrier properties of poly (ethylene-co-vinyl alcohol) film. Radiation Physics and Chemistry, v. 199, p. 1-10, 2022. DOI: 10.1016/j.radphyschem.2022.110343

    Abstract: Graphene 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.

    Palavras-Chave: graphene; oxide minerals; synergism; electron beam fusion reactors; radiations; polyethylenes; tensile properties; morphology

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  • IPEN-DOC 24661

    OIDE, MARIANE Y.T.; SATANA, JULYANA ; WELLEN, RENATE; VALENZUELA-DIAZ, FRANCISCO; GUVEN, OLGUN; MOURA, ESPERIDIANA . The influence of clay reinforcement on the properties of recycled polymer foams. In: LI, BOWEN (Ed.); LI, JIAN (Ed.); IKHMAYIES, SHADIA (Ed.); ZHANG, MINGMING (Ed.); KALAY, YUNUS E. (Ed.); CARPENTER, JOHN S. (Ed.); HWANG, JIANN-YANG (Ed.); MONTEIRO, SERGIO N. (Ed.); FIRRAO, DONATO (Ed.); BROWN, ANDREW (Ed.); BAI, CHENGUANG (Ed.); PENG, ZHIWEI (Ed.); ESCOBEDO-DIAZ, JUAN P. (Ed.); GOSWAMI, RAMASIS (Ed.); KIM, JEONGGUK (Ed.). Characterization of Minerals, Metals, and Materials. TMS. Cham, CZ, Switzerland: Springer International Publishing AG, 2018. p. 703-712, (The Minerals, Metals & Materials Series). DOI: 10.1007/978-3-319-72484-3_75

    Abstract: Poly [(ethylene)-co-(vinyl acetate)] (EVA) is a thermoplastic copolymer composed of randomly distributed polyethylene and polyvinyl acetate sequences within the molecular chain. EVA combines toughness with excellent flexibility, impact and puncture resistance. Because of these properties, this material is largely used for foam production as padding in equipment for various sports and as a shock absorber in sport’s shoes. This work aims to study the influence of clay reinforcement on the performance of recycled polymer foams. The blend containing recycled HDPE (high density polyethylene) and recycled EVA (70/30 wt%, respectively) reinforced with 2 wt% of clays were prepared by melt extrusion, using a twin-screw extruder to obtain the composites. The composites and foaming agent were fed into a special single screw extruder for foaming. The samples of HDPE/EVA/Clay foams were characterized by tensile test, Field Emission Scanning Electron Microscopy (FE-SEM), Thermogravimetric Analysis (TG), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD), density measurement and the correlation between the results was evaluated.

    Palavras-Chave: polyethylenes; polymerization; polyvinyls; clays; foams; nanocomposites

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