Effect of the structure of the hydrophobized mesoporous silica gel on the colloidal damper hysteresis

Colloidal damper (CD) represents an application of nanotechnology in the field of mechanical engineering. CD is complementary to hydraulic damper (HD), having a cylinder-piston construction, but oil is replaced by a colloid consisted of a mesoporous matrix and a lyophobic liquid. In this experimental work the mesoporous matrix is from silica gel modified by linear chains of alkyldimethylchlorosilanes and aqueous solutions, i.e., mixtures of water and antifreeze agents, are associated liquids. Recording the CD hysteresis loop one determines the dissipated energy and damper efficiency. Influence of the grafted molecule, endcapping and pore size on the CD cycle is presented and optimum hydrophobization versus pore size is settled. Variation of the dissipated energy and efficiency with pressure and silica gel quantity is illustrated. Maximum efficiency is reached at the optimum loading pressure and a quantity of liquid which equals the pore volume of silica gel. CD efficiency (45-92%) is found to be higher than HD efficiency (30-40%).