Study and characterization of epoxy resin composites in gel coat with different contents of inorganic fillers

The gel coat epoxy resins used in mold lamination need to give the piece a high gloss and homogeneity, guaranteeing aesthetic quality and mechanical properties. In this way, the present work aimed to study the formulation of epoxy resin composites/inorganic fillers aiming at the improvement of physical and mechanical properties. A complete experimental design was carried out with three central points, totaling 11 formulations of epoxy gel coat composite, in which the influence of titanium dioxide (TiO2) (20, 45 and 70 phr), calcite (0, 20 and 40 phr) and barite (0, 20 and 40 phr) in the physical properties, density and drainage level and hardness. Considerable variations were observed in the properties of the composites with the modifications made in the formulations. It was verified in the experimental planning that the variable density was significant in relation to the three independent variables and not significant in the lack of fit, in this way, the model adequately represented the experimental behavior. For the variable hardness, the linear model did not satisfactorily describe the influence of the loads. According to the tests carried out, it was observed that with reduction of TiO2 characterized an increase in hardness, therefore, a reduction in density. On the other hand the baryta exerted a positive influence on the two properties and the calcite did not present significant influence. Regarding the level of runoff, the samples that presented the greatest amount of loads were the ones that performed best on this property. Finally, a new formulation was performed that was validated by the density model (60 parts TiO2, 30 parts calcite and 20 parts barite) that met the specifications.