Process and equipment for drying a polymeric aerogel in the presence of a supercritical fluid

A process for obtaining an aerogel from a polymeric material that is in the form a sol-gel in an organic solvent, the process being carried out in plural pressure containers that are each connected to a common supply system, and comprising the steps of:

• exchanging the organic solvent for a fluid from the common supply system having a critical temperature below a temperature of polymer decomposition;
• supercritical drying the fluid/sol-gel;
• wherein the exchanging and supercritical drying steps are carried out in each of the pressure containers and include successive steps of contacting the initial sol-gel with a stream of the fluid at different pressures and temperatures wherein the pressure containers are operated dependently on each other so that concurrently each of the pressure containers is performing a different one of the successive steps;
• and
• the successive steps submitting the product in each of the pressure containers to the fluid with pressure and temperature following a curve that starts with a pressure and a temperature so that the fluid is in a liquid state, and thereafter increase the pressure and temperature to a pressure higher than a critical pressure and a temperature higher than a critical temperature so that the fluid is not in a liquid or gaseous state and then decrease the pressure and temperature so that the fluid enters a gaseous state, and the successive steps reach an end of a cycle when the fluid reaches an initial pressure in a gaseous state, whereby the fluid does not change state directly from a liquid to a gas.