Abstract

The relationship between the molecular structures of lubricant additives and their anti-wear properties was assessed using 36 nitrogen-containing heterocyclic organic compounds to generate quantitative structure tribo-ability relationship (QSTR) models. In the modeling process, the molecular structure of the base oil was employed as the solvation factor, employing n-octadecane as a substitute for the liquid paraffin used to generate the original experimental data. Comparative molecular field analysis (CoMFA)-QSTR and comparative molecular similarity indices analysis (CoMSIA)-QSTR models incorporating solvation by n-octadecane were established and compared with QSTR models that did not involve solvation. The solvation CoMFA-QSTR and CoMSIA-QSTR models exhibited excellent fitting abilities and were highly robust when predicting lubricant performance. These models were superior to non-solvation models in this regard. These models also generated useful information regarding potential changes to molecular structure to improve anti-wear properties. Electrostatic fields were found to be very important factors in anti-wear models. Because the original experiments used a non-polar base oil, the solvation factor had no obvious effect on the anti-wear characteristics of the polar additives and so the predictive abilities of the solvation and non-solvation models were similar.

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