Preparação e caracterização do nanocompósito fotossensível de acrílico/argila para manufatura aditiva

Abstract

The high cost in manufacturing parts for the of Additive Manufacturing technology (AM) boosted in recent years several studies aiming the development of new equipment and new materials. With this in mind, a photosensitive resin previously developed by the research group to which this work is inserted with components available in the domestic market, presented low mechanical properties and high shrinkage of the material compared to the materials available on the market. One alternative for improving these properties is to obtain nanocomposites. They comprise a new class of materials in which inorganic substances of nanometric dimensions, such as clays and other minerals, are finely dispersed within a polymeric matrix. Thus, this study aims to prepare and characterize a photosensitive acrylic / clay nanocomposite cured by exposure to UV-C radiation, with mechanical properties of tensile, bending and hardness, and shrinkage propers for use in AM process. Therefore, the original formulation, composed of trimethylolpropane triacrylate (TMPTA®) and Acid Methacrylate Modified (Ebecryl 171®)monomers, Amina acrylated (Ebecryl 7100®)oligomer, Co-initiator Benzophenone 99% (Additol BP®) and the photoinitiator Additol LX® was tested with the addition of the clays Cloisite 20® and BN-CT in concentrations of 0.5%, 1.0% and 1.5% (w/w) of total weight. After preparing these formulations, obtained by dispersion 1 (magnetic stirring) and 2 (magnetic stirring and ultrasound), it was prepared specimens by the principle of adding successive layers by AM. The characterization was perform by shrinkage analysis, tensile strength, bending and hardness tests, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry (TG) and viscosity. The warpage of the material showed an average improvement of 18.27% with the Cloisite 20® clay and 11.30% with the BN-CT clay. The results of the tensile, flexural and hardness testing did not show significant increases in mechanical properties. The SEM showed no delamination between the layers after the bending test was performed. The XRD analysis showed no diffraction peak, suggesting the formation of nanocomposite with intercalated and / or exfoliated structure for all formulations with clay. The TG test showed that the addition of clay in the formulations presented no significant improvements in thermal stability of the nanocomposite. The viscosity showed no improvement at a temperature of 25 °C, but showed a significant reduction in viscosity at 35 °C. Although not very promising results in terms of mechanical strength, the formulations with clay can be used in the AM considering these limitations.