Studies of the improvement of the viscosity of natural ester liquids

This work reports on an experimental study of the improvement of the viscosity and cold flow behavior of natural ester liquids without compromising on the excellent fire safety (> 300°C). Material variations in the form of a change in the molecular structure of the natural ester oil and as blends of a natural ester liquid with two different compounds are investigated. The impact of the molecular structure and blend concentration on the kinematic viscosity at different temperatures, the crystallization behavior (measured by differential scanning calorimetry (DSC)) and on the flash point is investigated. Results show that improvement of all physical properties at a time is a difficult task. The paper highlights the fact that by adding just one compound to a natural ester liquid it is impossible to improve thermal cooling properties (viscosities) and cold flow behavior (crystallization properties) without compromising the fire safety at the same time.