| Abstract: | Influence of the Chemical Structure in Regard to the Air Release Properties and the Hydrolytic Stability of Esters Esters, based on fatty chemical basis, are of great importance for the lubricant industry as efficient, biodegradable basestocks and additives. The structure possibilities and synthetic variations of ester oils are described. Basic datas are presented inclusive application areas. Parameters like air release properties and hydrolytic stability possess a central function in special applications like hydraulic fluids or compressor lubes. Oil dispersed air bubbles influence the compressibility and can cause disturbances in oil containing systems. Esterhydrolysis by water are followed by precipitation, decompositions and increased corrosivity. The determination of the air release according DIN 51 381 and the hydrolytic stability leanded against ASTM D-2619 are explained. A great number of esters based on primary and polyhydric alcohols in combination with branched and unbranched, saturated and unsaturated mono- and dicarboxylic acids were tested. Structure-effects rules were fixed in dependence of viscosity, iodine value, branching degree and carbon chain length in order to improve the choice of esters for synthetic oils. |
