Viscosity Measurements of Dialkyl Adipates in the Temperature Range of (283 to 363) K and up to 40 MPa

Abstract

Viscosity is one of the most important properties for many scientific and technological applications, and therefore it has been the subject of an enormous effort of measurement, correlation, and interpretation. Reliable reference data can be of great help to improve viscosity accuracy, while for viscosity, the only accepted standard is the viscosity of pure water at 20 °C (the reference value recommended by ISO is 1.0016 mPa·s). With the technology and industry advancing, there is a new requirement for reference materials of viscosity covering wide temperature, pressure, and viscosity ranges in order to face the challenge that the order of magnitude of viscosity turns to 1014. Considering the dissatisfaction of the only standard, we put forward these candidates to meet the need of appropriate viscosity standard materials: dimethyl adipate (DMA), diethyl adipate (DEA), dipropyl adipate (DPA), and dibutyl adipate (DBA). These materials have the characteristics of easy to obtain, high purity, high thermal chemical stability, and especially larger viscosity value. In this work, the viscosity was experimentally measured by the vibrating wire viscometer over the temperature range of (283 to 363) K and at pressures up to 40 MPa. The combined expanded uncertainty of the reported viscosity is about 2 % with a confidence level of 0.95 (k = 2). The empirical Andrade–Tait equation was used to correlate the experimental results.