RAISING OF NEGATIVE-PRESSURE TO AROUND -200 BAR FOR SOME ORGANIC LIQUIDS IN A METAL BERTHELOT TUBE

Trends in negative pressure achieved over a few thousand cavitation ev ents were observed for ethanol, benzene and xylene in a stainless stee l Berthelot tube sealed with a pre-de-gassed Ni plug. When the system was repeatedly heated and then cooled alternately over a temperature r ange between 60-degrees-C and 10-degrees-C (temperature cycle), negati ve pressure increased steeply for earlier cycles and levelled off even tually as in a water-metal tube system. Owing to the cavitation histor y effect, negative pressures of around -200 bar, the highest ever atta ined for organic liquids in the Berthelot method, were generated at ar ound 15-degrees-C in a useful volume (approximately 1 cm3). It has bec ome feasible to measure thermodynamic properties of organic liquids un der negative pressure, since the pressures were up to half of the homo geneous nucleation limits of cavitation.