Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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12 resultados
Resultados da Pesquisa
- Cross-linked polyethylene (XLPE) as filler in high-density polyethylene: Effect of content and particle size(2019-01-22) FREITAS, R. S.; Bonse B.C.© 2019 Author(s).Cross-linked polyethylene (XLPE) scrap from electrical wire and cables was micronized and separated in average particle sizes of 100, 500 and 900 micrometer, after which sheets of XLPE concentrates in high-density polyethylene HDPE were produced, using a calendaring process. The sheets were ground and incorporated into HDPE by means of a twin-screw co-rotating extruder and subsequently injection molded into test specimens. A 2 by 2 factorial design with center point was used, where XLPE contents varied between 1 and 9 wt% and average particle size between 100 and 900 micrometers were assessed as to the effect of XLPE content and particle size on HDPE mechanical properties. Increase in XLPE content significantly increased only impact strength, and decreased tensile and flexural strength, and flexural modulus. The effect on tensile modulus and strain at break was not significant for the adopted 95% confidence interval. The increase in XLPE average particle size affected positively only impact strength of the material, and decreased strain at break and flexural modulus. The effect on tensile and flexural strength and on tensile modulus was not significant for the adopted 95% confidence interval. The interaction between the two variables decreased impact strength and increased tensile modulus, and was not significant for the other investigated properties.
- Nanocomposites of PLA containing ZnO nanofibers made by solvent cast 3D printing: Production and characterization(2019) Nonato R.C.; Mei L.H.I.; Bonse B.C.; Chinaglia E.F.; Morales A.R.© 2019 Elsevier LtdPLA nanocomposites containing 1 wt% ZnO nanofibers have been prepared by solvent-cast 3D printing. The ZnO nanofibers were produced by electrospinning and dispersed in PLA by ultrasound. Scanning electron microscopy revealed that the fibers were dispersed throughout the nanocomposite. Surface specimen assessment by atomic force microscopy indicated the presence of nanofibers near the surface of the nanocomposite. TGA tests showed the nanocomposite had a lower thermal stability than the neat PLA, probably induced by PLA hydrolysis catalyzed by ZnO. DSC results revealed higher crystallinity in the nanocomposite, induced both by the presence of ZnO nanofibers and by the 3D printing process, though the 3D printing process showed to be more important in increasing the crystallinity. XRD results also showed a higher crystallinity for the nanocomposite. The study opens an interesting field for the development of PLA/ZnO nanocomposites using ZnO nanofibers made by electrospinning, e.g. in medical and packaging applications.
- Mechanical and thermal behavior of aged composites of recycled PP/EPDM/talc reinforced with bamboo fiber(2018) Inacio A.L.N.; Nonato R.C.; Bonse B.C.LtdNatural fiber reinforced thermoplastic composites have been widely studied, mostly for environmental and economic reasons. One promising application is in the automotive industry, which widely uses talc filled EPDM (ethylene-propylene-diene monomer) toughened polypropylene (PP) for manufacturing interior and exterior vehicle components. It is important to analyze the durability of these materials since automotive vehicles have a long life cycle. The aim of this study was to assess mechanical and thermal properties of aged composites containing bamboo fiber reinforced recycled talc-filled PP/EPDM compatibilized with maleic anhydride grafted polypropylene (PP-g-MAH). Composites were prepared according to a 2 by 2 factorial design with center point, in a Haake twin screw extruder and injection molded. Specimens were aged for seven days at 90 °C in a chamber with hot air circulation. Addition of bamboo fiber significantly increased tensile and flexural strength, modulus and fatigue life, and decreased elongation at break and impact strength. Addition of the compatibilizer had a positive effect only on tensile and flexural strength, and fatigue life whereas the effect was negative on elongation at break and impact strength. The addition of fiber and PP-g-MAH, at levels exceeding 2 wt%, increased the degradation temperature of the fiber.
- Correlating different techniques in the thermooxidative degradation monitoring of high-density polyethylene containing pro-degradant and antioxidants(2018) Antunes M.C.; Agnelli J.A.M.; Babetto A.S.; Bonse B.C.; Bettini S.H.P.© 2018 Elsevier LtdDifferent techniques were used to assess the effect of a primary and a secondary antioxidant, separately, and in combination with a pro-degradant (manganese stearate) on the thermooxidative abiotic degradation of high-density polyethylene (HDPE). The parameters measured over time at three temperatures (60, 70 and 80 °C) were variation in carbonyl index (CI), by means of infrared spectroscopy; reduction in tensile strain at break, by means of mechanical testing; reduction in molar mass distribution by means of size exclusion chromatography (SEC). Regardless of the presence of primary or secondary antioxidants, the same levels of degradation were attained. However, contrary to the secondary antioxidant, the primary antioxidant significantly increased induction time of HDPE oxidative degradation processes, evidenced by the shift in the “CI versus time” curve and by the considerably longer time for the strain at break to reach minimal values. Increase in thermooxidation temperature reduced induction time significantly.
- Investigation on the use of coir fiber as alternative reinforcement in polypropylene(2010) Bettini S.H.P.; Bicudo A.B.L.C.; Augusto I.S.; Antunes L.A.; Morassi P.L.; Condotta R.; Bonse B.C.Polypropylene/coir fiber composites were prepared according to an experimental statistical design, in which the independent variables, coir fiber, and compatibilizer content, were varied. The compatibilizer used was maleic anhydride grafted polypropylene (PP-g-MA). Compatibilizer free composites were also prepared. Composites were processed in a corotating twin-screw extruder and submitted to mechanical and morphological analyses. The effects of the independent variables on the mechanical properties were assessed through tensile strength, elongation at break, flexural modulus, and impact strength. The morphological properties were assessed by scanning electron microscopy (SEM). The results indicated the need for using compatibilizers in the composites due to the incompatibility of PP and coir fiber. The variable with the strongest effect on the properties was coir content, whose increase caused increase in tensile strength, impact strength and elastic modulus, and decrease in elongation at break. The presence of PP-g-MA was fundamental to achieving the aforementioned results. The effect of increasing compatibilizer content was only observed for the elastic modulus. © 2010 Wiley Periodicals, Inc.
- Effect of sawdust surface treatment and compatibilizer addition on mechanical behavior, morphology, and moisture uptake of polypropylene/sawdust composites(2010) Bettini S.H.P.; Bonse B.C.; Melo E.A.; Munoz P.A.R.Polypropylene/sawdust composites were investigated to assess the effect of sawdust surface treatment and compatibilizer addition on polymer/fiber adhesion. Two silane coupling agents were used for sawdust surface treatment: vinyl-tris (2-methoxyethoxy) silane and (3- aminopropyl)triethoxysilane. Maleic anhydride grafted polypropylene was used as compatibilizer. Composites were prepared in a corotating twin-screw extruder coupled to a Haake torque rheometer and submitted to tensile and bending tests as well as scanning electron microscopy (SEM). Moisture uptake tests were also performed. Results showed that incorporation of untreated sawdust to polypropylene (PP) caused reduction in composite tensile strength and increase in stiffness. When the only treatment used was surface modification with silane coupling agents, no significant changes were observed in mechanical properties. However, when compatibilizer was added to the composites, tensile strength was increased, and % elongation at break reduced, indicating improved system compatibility. The composite presenting the highest increase in tensile strength was that containing sawdust treated with amino silane in addition to the compatibilizer. SEM analyses corroborated the mechanical property results. © 2009 Society of Plastics Engineers.
- A study of PP/PET composites: Factorial design, mechanical and thermal properties(2016) Nonato R.C.; Bonse B.C.© 2016 Elsevier LtdDue to the economic importance of polypropylene (PP) and polyethylene terephthalate (PET), and the large amount of composites made with PP matrix and recycled PET as reinforcing material; an investigation was performed regarding the mechanical and thermal behavior of PP composites containing recycled polyethylene terephthalate fibers (rPET). Interfacial adhesion between the two materials was achieved by adding a compatibilizer, maleic anhydride grafted polypropylene, PP-g-MA. Mechanical behavior was assessed by tensile, flexural, impact and fatigue tests, and thermal behavior by HDT (Heat Deflection Temperature). Fractured surfaces and fiber were investigated by scanning electron microscopy. Multiple regression statistical analysis was performed to interpret interaction effects of the variables. Tensile strength, tensile modulus, flexural strength, flexural modulus and HDT increased after rPET fiber incorporation while strain at break, impact strength and fatigue life decreased. Addition of compatibilizer increased tensile strength, flexural strength and flexural modulus, fatigue life and HDT while tensile modulus, strain at break and impact strength decreased. However, at low fiber content, the impact strength increased, probably due to nucleation effects on PP.
- Recycled PP/EPDM/talc reinforced with bamboo fiber: Assessment of fiber and compatibilizer content on properties using factorial design(2017) Inacio A.L.N.; Nonato R.C.; Bonse B.C.© 2017 Elsevier LtdThermoplastic composites reinforced with natural fibers have attracted the attention of many researchers, not only for environmental concerns, but also for economic reasons, recyclability, ease of processing, etc. One promising application is in the automotive industry due to their low cost and weight. This industry is increasingly pressured to produce vehicles that consume less fuel and are less polluting. Therefore, plastics reinforced with fibers are required to produce lighter parts to replace the much more abrasive glass fiber and mineral filled composites. One of the most widely used polymers in the automotive sector for manufacturing interior and exterior vehicle components is talc filled EPDM (ethylene-propylene-diene monomer) toughened polypropylene (PP). In this context, the aim of this study was to assess mechanical and thermal properties of bamboo fiber reinforced recycled talc filled PP/EPDM composites compatibilized with maleic anhydride grafted polypropylene (PP-g-MAH). Composites were prepared, according to a 22 factorial design with center point, in a Haake twin screw extruder with subsequent injection molding. Injected specimens were subjected to tensile, flexural, impact and fatigue testing. Morphological analyses were performed by scanning electron microscopy (SEM), and thermal analyses by thermogravimetry (TGA) and differential scanning calorimetry (DSC). Addition of bamboo fiber significantly increased tensile and bending strength, modulus and fatigue life, and decreased elongation at break and impact strength. On the other hand, addition of the compatibilizer had a positive effect only on tensile and flexural strength, and fatigue life whereas the effect was negative on elongation at break and impact strength. The addition of fiber and compatibilizer did not appreciably affect the matrix melting temperature, but slightly increased crystallization temperature and in some cases the degree of crystallinity.
- Process parameters in the manufacture of ceramic ZnO nanofibers made by electrospinning(2017) Nonato R.C.; Morales A.R.; Rocha M.C.; Nista S.V.G.; Mei L.H.I.; Bonse B.C.© 2016, Springer-Verlag Berlin Heidelberg.Zinc oxide (ZnO) nanofibers were prepared by electrospinning under different conditions using a solution of poly(vinyl alcohol) and zinc acetate as precursor. A 23 factorial design was made to study the influence of the process parameters in the electrospinning (collector distance, flow rate and voltage), and a 22 factorial design was made to study the influence of the calcination process (time and temperature). SEM images were made to analyze the fiber morphology before and after calcination process, and the images were made to measure the nanofiber diameter. X-ray diffraction was made to analyze the total precursor conversion to ZnO and the elimination of the polymeric carrier.
- Fatigue life of coir fiber reinforced PP composites: Effect of compatibilizer and coir fiber contents(2013) Antunes M.C.; Moraes D.V.O.; Magnabosco R.; Bonse B.C.; Bettini S.H.P.The fatigue behavior of polypropylene/coir fiber composites was investigated. Composites were prepared according to an experimental statistical design, in which the independent variables coir fiber and compatibilizer content were varied. The compatibilizer used was maleic anhydride grafted polypropylene (PP-g-MA). Compatibilizer free composites were also prepared. Composites were prepared in a corotating twin-screw extruder and the mechanical behavior of polypropylene/coir fiber composites were assessed through monotonic (tensile) and cyclic (fatigue) tests. Fatigue load controlled tests were conducted under tension-tension loads at a frequency of 6 Hz. The fracture mechanism was accompanied by surface fracture analyses using scanning electron microscopy (SEM). The results indicated the need for using compatibilizer in the composites; however, increase in compatibilizer content did not affect composite fatigue lifetime. Coir content was the variable with the strongest effect on composite properties; increasing this variable caused significant increase in fatigue life. © 2013 Society of Plastics Engineers.