V.P. Parkalov’s scientific contributions

Influence of length of alkyl radical in liquid-crystal cholesterol n-alkanoate on lubrication properties and wear resistance was studied. Lubrication properties were estimated by means of stress of copper rod drawing through draw providing deformation degree 28,3%, wear resistance was estimated using wear index defined on four-ball friction machine. It was established that with increasing alkyl radical length their lubrication properties increased and wear resistance reduced. The findings of an investigation were due to intermolecular interaction in relation to alkyl radical length in cholesterol n-alkanoates.

The paper describes the results of investigations performed on the lubricity of liquid crystals (LCs) and their solutions in petroleum and synthetic oils. LCs present in a lubricant were shown to lead to a decrease in friction and wear for solids. The LC concentration in lubricants was shown to affect the microrelief of the surfaces in frictional contact. The mechanism of LC-bearing surface interaction is discussed for the dynamic mode of contact.

The use of a derivator for sediment analysis makes it possible to automatically record the change in the specimen weight and the rate of change during the process of its heating. The authors describe the use of the derivator as a sediment balance. Modifications are described which make it possible to obtain the sediment curves, which in turn makes it possible to establish the fractional composition of the powder. Some special aspects of the use of the derivator in sediment analysis in place of a torsion balance are discussed.

We study the lubricating action of individual cholesteric liquid crystals (CLC) and nematic liquid crystals (NLC) and their solutions in vaseline oil in drawing copper. It is shown that the lubricity of the individual CLC increases with reduction of their first phase transition temperature. This pattern does not show up for the NLC. The solutions of CLC in vaseline oil have higher lubricity than the straight oil, the NLC solutions, and surfactants, but their lubricity is comparable with that of the CLC in the mesomorphic phase. The higher lubricating action of the CLC in comparison with the surfactants is apparently due to the location of the plane of sliding not in the plasticized metal layer but rather in the lubricant layer, consisting primarily of surfactant molecules and secondarily of CLC molecules.

It is shown that liquid crystals (LC), prone to planar orientation on the bearing surface in the mesophase, reduce the friction of solid bodies of various nature in greater measure than in the isotropic liquid phase and make it possible to improve the operational properties (friction coefficient and load capacity) of lubricants.