Multiresponse Optimization of a Hydraulic Oil Formulation by Mixture Design and Response Surface Methods

Abstract

The field performance of hydraulic oils depends on factors such as the viscosity index (VI), flash point (FP), pour point (PP), and demulsibility. A hydraulic oil formulation was performed by applying a multiresponse optimization, for which the PP was minimized, the FP, demulsibility, and VI were maximized. The range of viscosities at 40 and 100 °C was selected according to the International Organization for Standardization (ISO) viscosity grade for hydraulic oil. The experiments were accomplished according to an extreme vertices mixture design using solvent neutral-100 (SN-100) and SN-500 as major components and polyisobutene (PIB) as minor component. The results shows that the optimum formulation consisted of 37.5% SN-100, 60% SN-500, and 2.5% PIB, and the values of FP, PP, VI, demulsibility at 30 mins and viscosities at 40 and 100 °C were equal to 227 °C, −6 °C, 107.5, 28/2012/40, 67.3 cS, and 9 cS, respectively.