Effect of Graphene and Ionic Liquid Additives on the Tribological Performance of Epoxy Resin

In the present study, we have determined the effect of graphene (PG), the ionic liquid (IL) and PG modified by mechanical blend with the IL 1-octyl-3-methylimidazolium tetrafluorobotate (IL + PG) on the tribological performance of epoxy resin (ER). IL + PG stable suspensions have been added to an epoxy resin (ER) matrix to obtain the new nanocomposite (ER + IL + PG), and its tribological performance has been compared with that of neat epoxy resin and with the nanocomposites containing PG (ER + PG) or IL (ER + IL). While neat ER presents a high dynamic friction coefficient of up to 0.31 and a severe wear with a specific wear rate of 8.1 x 10(-4) mm(3) N(-1)m(-1), the new nanocomposites show negligible surface damage, as determined by surface roughness and profilometry. All nanocomposites show low friction coefficients and negligible wear. The maximum friction reduction, up to a 70 %, is obtained for ER + PG. Results are discussed upon the basis of TEM microscopy, SEM microscopy and EDX analysis, differential scanning calorimetry, thermogravimetric analysis and dynamic mechanical analysis. Addition of IL or IL + PG has a plasticizing effect on ER, while addition of PG increases the thermal stability and stiffness of ER. PG shifts the storage modulus onset and in the loss modulus and tan delta maximum peaks to higher temperatures, while a shift to lower values is observed with addition of IL or IL + PG.