Introduction
Polyol esters (POEs) have being used as lubricants for
commercial applications because of their characteristic
properties and their environmentally safe usage.0 POEs
lubricants have favorable properties as refrigeration oils
compared to those of polyalkylene glycols. They are less
hygroscopic, have higher miscibilities with HFCs and CO0
refrigerants, and are miscible with mineral oils.0,0 Lubricants
based on polyol esters represent one of the most
important types of synthetic lubricants.0,0 Their high
thermal stability and good lubricating properties have
resulted in a wide range of applications from the textile
/>industry to gas turbine motors.0 To minimize costly experimentation,
new models that can predict the thermodynamic
and transport properties of POEs would be very
useful,0 but for this purpose a more complete database of
thermophysical properties over wide temperature and
pressure ranges is needed.
One of the goals of our present project is to provide the
thermophysical properties over wide temperature and
pressure ranges for one type of POE with known structure,
namely, pentaerythritol tetraalkyl esters (PEs),0,0 which
consist of an isopentane nucleus linked to four identical
alkyl ester chains (branched or linear). With this aim, in
the present work the volumetric properties of pentaerythritol
tetra(0-ethylhexanoate), PEB0, have been studied. To
our knowledge, only Wahlstro¨m and Vamling0 have reported
density measurements for PEB0 over the temperature
interval of (000.00 to 000.00) K and only at atmospheric
pressure. Shobha and Kishore0 have published the
densities at 0.0 MPa from (000 to 000) K for pentaerythritol
tetraoctanoate, which is isomeric with PEB0.