Síntese de microcápsulas de poli(ureia formaldeído)/ENB e avaliação do mecanismo de autorreparo em resina epóxi.

Abstract

The necessity of repairing damages in engineering materials caught the attention of several researchers to seek inspiration in natural self-healing mechanisms, and develop similar systems, capable of recover cracks in polymeric resins. The use of microcapsules filled with healing agents has been shown very versatile to this application, because of its ease of synthesizing and efficiency in use. In this study pol(urea-formaldehyde) microcapsules filled with 5-etilidene 2-norbonene (ENB) were synthesized by in situ method and its properties were evaluated by SEM, FTIR and TGA. The microcapsules were added to a commercial epoxy resin and its mechanical properties were investigated through flexural test. It was observed in the micrographies that microcapsules with medium size of 120 µm, homogeneous spherical morphology and surface roughness were obtained. The composition of microcapsules shell was confirmed by the FTIR spectrum, and the thermal stability was approximately 200 °C, as seen in TGA curve. The specimens without microcapsules had higher maximum stress values than the samples with microcapsules, which was expected, because stress concentration points inside the epoxy resin were possibly created by the microcapsules. The synthesis method was satisfactory to obtain homogeneous, free flowing, microcapsules, also thermally stable to the needs of the applications. Flexural test showed there was no instantaneous self-healing and that microcapsules might have acted as tension points inside the resin.