Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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2 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.
- A Recycling-Focused Assessment of the Oxidative Thermomechanical Degradation of HDPE Melt Containing Pro-oxidant(2019-12-21) BABETTO, A. S.; ANTUNES, M. C.; BETTINI, S. H. P.; Baltus Cornelius BonseThis study shows the effect of a pro-oxidant (oxo-biodegradable) additive on the oxidative thermomechanical degradation of high-density polyethylene (HDPE). It also allows us to predict the behavior of the material when subjected to mechanical recycling or to biodegradation. When HDPE, one of the most consumed thermoplastics worldwide, is transformed into a product or when subjected to primary and/or secondary recycling it will undergo thermomechanical degradation. According to current standards HDPE is not biodegradable, therefore pro-oxidants are added to many HDPE products, which can compromise the product's life. Knowledge on the influence of pro-oxidants on HDPE in the melt is limited and the objective of this study is to assess the behavior of HDPE containing pro-oxidant manganese stearate (MnSt) in the oxidative thermomechanical degradation process. Thermomechanical degradation tests were conducted in a closed-chamber torque rheometer. FTIR and SEC results agreed with those of torque rheometry and showed that oxidative thermomechanical degradation of HDPE increases with increasing manganese stearate concentration. Degradation resulted in an increase in the number of oxygenated functional groups, mainly ketones, aldehydes and carboxylic acids, and reduction in the weight-average molar mass of HDPE. MnSt may have acted both as a lubricant and pro-oxidant during processing with predominance of one or the other effect at different stages along the oxidative thermomechanical degradation of HDPE.