Estudo termomecânico da resina poliéster/nanopartículas de haloisita com aditivo retardante de cura

Abstract

In this work, the addition of haloysite nanoparticles was performed in the polyester resin additivated with powder from cupuaçu bark to study the influence that the nano clay had on the thermal and mechanical behavior of this composite. The attainment of the bark powder occurred through the comminution of the raw material in a ball mill for about 12 hours and, finally, the ground material was passed through a sieve with apertures of 75 µm (200 mesh), obtaining about 300 g of pericarp. This passed material was used as the curing retardant of the unsaturated polyester resin.Subsequently, composite plates of haloisite nanoparticles were made in mass proportions of 0 %, 1 %, 2 % and 4 % added to unsaturated polyester resin additivated with cupuaçu shell poder. For characterization of the thermomechanical properties of the composite obtained, a mechanical tensile test, TG and DSC thermal analyses, SEM optical analysis coupled with EDS to verify the matrix/loads interface in the fracture region of the tensile test and quantification of the chemical elements found, and Curing Kinetics test to verify the influence of nano clay on the additive resin cure were performed. It was observed in the SEM/EDS analysis that there was not a good interaction of the interfaces of the fillers in relation to the matrix. In the EDS analysis the aluminum element was identified, characteristic of the Haloisite nanoparticle composition (Al2Si2O5 (OH)4). For the specimens with added halloysite nanoparticles, all showed maximum stress values above about 11 % to 19.2 % of the Resin/Cupuaçu specimens, but lower than the pure polymer by about 8 % to 15 %. In the TG and DSC analysis no significant variation of the thermal degradation process of the polyester/cure retardant was observed with the addition of 1 %, 2 % and 4 % of nanoparticles. In the Cure Kinetics analysis it was observed that the composition with 4 % of halloysite nanoparticle, had a higher activation energy than the others, then an increase in energy and after that the reduction of activation energy as the conversion increased, which indicates to us an acceleration reaction. This increase during the conversion path is due to the Nano clay.