Production and characterization of nanocellular polyphenylsulfone foams

Nanocellular foams have been produced by means of a gas dissolution process using polyphenylsulfone (PPSU) as matrix polymer. Cell sizes in the range 20-30 nm and cell nucleation densities higher than 1015 cm−3 have been achieved for materials with relative densities in the range 0.65-0.75. The influence of both saturation pressure and foaming temperature has been studied. On the one hand, it has been proved that there is a large influence of the amount of gas (CO2) absorbed in the final cellular structure, in fact it has been found a critical CO2 uptake between 9% and 9.5% at which the cell sizes evolve from the micro to the nanoscale. On the other hand, it has been found that there is a wide range of foaming parameters (foaming time and foaming temperature) in which nanocellular foams can be produced.