Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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4 resultados
Resultados da Pesquisa
- 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.
- 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.