Heat capacity, density, surface tension, and contact angle for polyalphaolefins and ester lubricants

Abstract

Thermophysical properties of lubricants are important to understand which ones are appropriated for the industrial conditions expected. Thermophysical properties of two different families of lubricants were analysed: polyalphaolefins (PAO6, PAO20, PAO32 and PAO40) and four ester-based lubricants. Specific heat capacity, density, surface tension, and contact angle were experimentally determined over a broad temperature range through methods such as μDSC, U-tube vibration, drop volume, and sessile drop method, respectively. A clear difference between the two families was observed due to their structure and composition, grouping by nature. Ester-based lubricants showed lower specific heat capacity but higher surface tension and density than polyalphaolefins. PAO6 clearly has the lowest density and surface tension and presents the highest specific heat capacity of all lubricants, and together with trimethylolpropane trioleate, TMPTO, presents the best wettability. Heat capacity values were used to test the validity of two predictive methods