Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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4 resultados
Resultados da Pesquisa
- Properties of lignocellulosic composites of coffee husk filled polypropylene(2020-01-10) LEAL, H. D. A.; BABETTO, A. S.; BONSE, B. C.© 2020 Author(s).Ground coffee husk has been incorporated into polypropylene (PP) at 20, 30 and 40 wt%, along with a PP maleated compatibilizer at 10 wt% relative to the coffee husk, by means of a co-rotating twin-screw extruder and subsequent injection molding into test specimens. In relation to neat PP, the 40 wt% composite showed an increase in flexural strength, flexural modulus, tensile modulus and heat distortion temperature of about 35, 90, 75 and 45%, respectively. However, strain at break, impact and tensile strength decreased by around 95, 40 and 20%, respectively. The presence of coffee husk practically did not affect PP melt temperature, but increased both composite's degree of crystallinity, measured by DSC, and temperature at maximum degradation rate, measured by TGA.
- Effect of process parameters and composition on mechanical, thermal, and morphological properties of polypropylene/sawdust composites(2008-05-15) Sílvia Bettini; Uliana A.T.; Holzschuh D.Polypropylene/sawdust composites have been prepared according to a statistical experimental design, with varying sawdust and compatibilizer (maleic anhydride grafted PP) concentrations. To investigate process conditions, composites were first extruded in a twin screw extruder coupled to a Haake torque rheometer, without degassing, and then reextruded in a Werner Pfleiderer twin screw extruder, with two degassing zones. Process conditions were analyzed according to statistical techniques. Effect of the variables on mechanical properties was assessed through flexural modulus, tensile strength, and percent elongation at break and morphology was assessed by scanning electron microscopy. Comparison between the extruded and reextruded compounds indicated the need to reduce moisture, prior to and during processing, as well as the need of effective mixing of the compounds. Sawdust concentration showed to be the variable which affected most all properties assessed. Increase in sawdust concentration resulted in increased composite stiffness. The presence of the compatibilizer caused a slight increase in tensile strength and reduction in percent elongation at break, indicating improved adhesion at the PP/ sawdust interface. The reprocessed compounds were also analyzed by differential scanning calorimetry. © 2008 Wiley Periodicals, Inc.
- Sawdust reinforced polypropylene: Effect of plasticizer incorporation method and properties(2018-07-11) MAZARIM, G. C.; BONSE, B. C.© 2018 Author(s).Polypropylene reinforced sawdust composites containing paraffinic and vegetable plasticizer, at 5 and 10 wt%, were prepared according to two methods. In the first method, PP, sawdust, compatibilizer and plasticizer were pre-mixed, extruded in a co-rotating twin-screw extruder and injection molded. In the second, plasticizer was added to the extruded composite pellets and then injection molded. The addition of plasticizer reduced tensile and flexural strength, as well as elastic modulus of the composite, and increased impact strength, tensile strain at break and toughness. As to plasticizer type, both had similar effects on impact strength, tensile strain at break and flexural modulus. With the paraffin oil, the increase in toughness of the PP sawdust composite was higher and the decrease in tensile and flexural strength was lower compared to the vegetable oil. Except for impact strength and flexural modulus the method of plasticizer incorporation, statistically, showed no difference in the investigated composite properties; however, deviation around the mean was higher when the plasticizer was added prior to injection molding, compared to addition in the pre-mixing stage.
- 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.