Navegando por Autor "Silva, Felipe de Andrade Oliveira"

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Resistência mecânica e térmica de compósitos reticulados de PVA/óxido de grafeno
(2019-12-19) Silva, Felipe de Andrade Oliveira; Ghislandi, Marcos Gomes; http://lattes.cnpq.br/3409757365313853; http://lattes.cnpq.br/0379100954556428
PVA composite films with citric acid and graphene oxide were synthesized via drop casting and crosslinked by heat treatment at 140° C for two hours. The influence of loads on mechanical, thermal and optical properties were characterized by tensile tests, thermogravimetry. and UV / VIS spectroscopy. The combined use of citric acid and graphene oxide proved to be very effective in promoting an increase in mechanical strength from 11.3 ± 1.4 MPa (pure PVA) to 37.1 ± 2.1 MPa (heat treated sample and 5% citric acid and 0.5% graphene oxide). However, there was a reduction in the maximum deformation from 333.0 ± 80.8% (pure PVA) to 84 ± 14%. The highest values obtained represent a 228% increase in mechanical strength and a 56% reduction in maximum deformation. The thermal stability of the films was analyzed by thermogravimetry; The addition of the fillers together with the heat treatment resulted in an increase in the degradation temperature from 269 ° C (pure PVA) to 325 ° C for the sample with 5% citric acid and 0.5 % graphene oxide. Optical properties were investigated by UV / VIS spectroscopy where yellowing due to heat treatment represented by a reduction in transmittance of 300-450 nm was observed. Keywords: Composites. Graphene. Cross-linking