空气在二甲基硅油和液压油中的溶解度

对于诸多工程运用场合, 获得空气在硅油以及液压油中溶解度可靠的数据至关重要. 针对已有测量装置及方法的不足, 建立了一种基于理想气体状态方程来确定气体溶解量的新型精密活塞式装置. 获得了温度为293.2及353.2 K, 压力在0-350 kPa范围内, 空气在500cSt 二甲基硅油中的本生溶解度表达式. 测量了298.2 K时20cSt二甲基硅油及国产32#抗磨液压油在多种气相压力下的本生溶解度. 精度及可靠性分析表明实验数据的误差范围为6%. 本生溶解度与气相压力呈较好的线性关系, 以摩尔分数表示的溶解度与压力呈非线性关系, 但可用Krichevsky-Ilinskaya方程拟合. 发现空气在相对分子质量差异很大的两种二甲基硅油中的本生溶解度很接近, 由此提出, 对于小分子的非极性溶质在聚合物溶剂中的溶解度, 用聚合物单体的摩尔数而不是聚合物分子摩尔数来表示摩尔浓度更有利于实验数据的外推和工程应用. 对于相对分子质量差别较大或无法确定相对分子质量的溶剂, 工程应用中适宜采用本生溶解度.

Solubility of Air in Dimethyl Silicone and Hydraulic Oils

For many engineering applications, it is important to obtain reliable data of the solubility of air in dimethyl silicone and hydraulic oils. Overcoming some drawbacks of previous methods for measuring gas-solubility, a new piston apparatus was established, in which the state equation of ideal gas was used to determine the amount of gas-dissolution. An expression of the Bunsen solubility of air in 500cSt silicone at temperatures of 293.2 and 353.2 K and in the gas-pressure range of 0-350 kPa was determined. The Bunsen solubilities of air in 20cSt silicone and Chinese 32# hydraulic oils at 298.2 K under various gas-pressures were also measured. Reliability and accuracy analyses indicated that the error range of the experimental data was about 6%. The Bunsen solubility and gas-pressure exhibited good linearity, while the relationship between the molar fraction and the pressure in the experimental range was nonlinear but could be well fitted by the Krichevsky-Ilinskaya equation. It was discovered that the Bunsen solubilities of air in silicone with quite different molecular mass were close to each other. The results suggested that the molar fraction based on the monomer mass was more appropriate than that based on the molecular mass for engineering extrapolation of the solubility data of small and non-polar solutes in polymer solvents. At last, for solvents containing much different or uncertain molecular mass, the commonplace in engineering applications, the Bunsen solubility was appropriate to give the dissolved gas concentration.