Synthesis of polymeric microcapsules filled with castor oil to improve epoxy tribological properties.
Synthesis, castor oil, polymeric microcapsules, epoxy, tribological properties.
Over the last five years researchers have synthesized microcapsules for smart coatings adding encapsuled agents in polymeric matrices. This field of materials engineering has gained notoriety for allowing specific features from tribology perspective generating self-lubrication and self-healing in systems where the movement between solid surfaces is essential in the functioning of mechanisms both natural and artificial. Thus, in this research, poly (urea formaldehyde) microcapsules filled with ricin oil were synthesized by in situ polymerization method and added in an epoxy matrix in the following mass percentages: 2.5%, 5% and 10%. The evaluation of tribological properties was developed with pin on disc tests in the conditions of 300 rpm 15N, in epoxy with microcapsules against a 52100 steel sphere, willing to quantify the coefficient of friction and the wear rate of the composite comparing with pure epoxy resin. As expected, spherical microcapsules were obtained with the desired composition and mean size of 413 ±175 µm, confirmed by FTIR and SEM images, respectively. Although all specimens had a decrease in coefficient of friction, the composite with 2.5% wt of microcapsules had a better output in tribological tests. The reduction in coefficient of friction is due to the action of ricin oil released from microcapsules, which forms a film typical of boundary lubrication regimen in the contact between the resin and the steel sphere.