Desenvolvimento e caracterização de um adesivo em matriz epóxi nanomodificada por grafeno

Abstract

The objective of this research was to develop an adhesive with addition of carbon-based nanoparticles. This choice was due to the fact that nanoparticles, especially those from graphite and graphene, are an emerging class of carbon-based nanomaterials with low cost and presents great potential to replace fillers materials used in the manufacture of polymer nanocomposites. Each nanoparticle of graphite consists of a 'stacked layers' of graphene having thicknesses ranging from 0.35 nm to 100 nm with high aspect ratio and large surface area. The adhesive with graphite nanoparticle is intended to be used in fixing reinforcement elements of the car body and may also be used in regions where the spot welding are not applied for cosmetic reasons. The components of this research are the front doors, rear doors and the hood. These components are the result of bonding inner and outer closure panels with adhesive in an operation called hemming process. The development of this adhesive with addition of carbon-based nanoparticles will be used on these parts. Were evaluated two dispersion methods of expanded graphite in an epoxy resin matrix with concentrations ranging from 0.25% to 3%. The expanded graphite HC11 IQ was supplied by Nacional de Grafite. It was measured the mechanical strength through apparent shear strength of single-lap-joint at room temperature and after exposure to temperature and humidity for 500 hours as a function of particle concentration and dispersion method. The nanocomposites were characterized by electron microscopy, X-ray diffraction and thermogravimetric analysis. From the results it was found that the best dispersion method was with the equipment called Grease Worker, producing structures with blocks of graphene with less than 100 nanosheets, the best mechanical performance has been that for a concentration of 3% of nanografite. In tests at room temperature there was an increase of 29.7% in the apparent shear strength in comparison with the pure adhesive. In tests of exposure was found that the more severe test was 500 hours in salt spray followed by 500 hours at 100 ° C and 500 hours in a humid chamber for all test conditions. Finally, a 3% concentration of nanografite in the epoxy adhesive at all conditions tested showed the best results.