Synthesis of polymeric microcapsules filled with castor oil to enhance tribological properties in epoxy resin

The addition of microcapsules (MCs) to a polymer matrix has been gaining attention because it facilitates the attainment of composite materials with better mechanical, chemical and functional properties that enhance its tribological properties. In this work, poly (urea formaldehyde) (PUF) microcapsules filled with castor oil were synthesized using an in situ polymerization method and then added to the epoxy matrix at mass percentages of 2.5%, 5% and 10%. Spherical microcapsules were obtained with the desired composition, confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) images. The surface of the composites was analyzed using the roughness parameters Ra, Rq, Rz, Rsk and Rku. The preliminary tribological properties were evaluated using tests with a pin-on-disk configuration. After the tribological tests, the wear track was characterized using SEM images. There was a reduction of approximately 50% in the coefficient of friction of the composites studied and the specimen with 2.5% microcapsules had the best self-lubricating performance, considering the characterizations of roughness and track sinking.