Texus 8 experiment - Effects of a surface tension minimum on thermocapillary convection

At equilibrium, n-heptanol aqueous solutions present a minimum of surface tension vs temperature. It has been shown that this minimum property persists in non-equilibrium conditions, in gravity and in microgravity. The experiment performed during the 6 min free flight of the Texus 8 high altitude research rocket shows that thermocapillary convection occurs from the cold to hot region in a liquid-gas interface of such an n-heptanol solution submitted to a thermal gradient in the range where the surface tension is increasing with the temperature.