Novel thermothickening lubricant with elastomeric nano-particles

Abstract

Inspired by the thermothickening phenomenon of polymer gels, a novel thermothickening silicone oil lubricant has been prepared by modification with silicon elastomeric nano-particles (Si-ENP). The modified lubricant has a remarkable improvement in viscosity when temperature rises from 40 °C to 100 °C. The modified silicone oil with 5 wt% Si-ENP exhibited a remarkably stable viscosity and the modified silicone oil with 15 wt% Si-ENP unexpectedly exhibited a 105% viscosity increase in the above temperature rise range. In contrast, neat silicone oil or silicone oil traditionally modified by 5 wt% olefin copolymers (OCP) saw a viscosity decrease by a factor of ten in the same range of temperature rise. It was also found that the average particle size of the Si-ENP in the silicon oil increased from 87.4 nm at 40 °C to 146 nm at 100 °C. Apparently, the normal viscosity loss with increased temperature was compensated by the continuous swelling of the Si-ENP particles. The thermothickening mechanism is the self-thickening of the Si-ENP modified lubricant in which part of the silicone oil become the solid phase in the swelled Si-ENP due to temperature rise.