The production of nanocellular polymers is a topic with increasing interest, due to the unique properties of these materials. Multiple polymer matrices have been chosen for this purpose, such as polyphenylsulfone, polycarbonate or polyetherimide. However, the most promising results have been obtained using polymethylmethacrylate (PMMA) as polymer matrix.
In order to change the cellular structure of nanocellular PMMA and therefore its final properties, different strategies have been followed. One approach is to use the heterogeneous nucleation mechanisms by adding nanoparticles or by using a nanostructured polymer blend. On the other hand, it has been proved that process parameters strongly affect the final cellular structure. Nevertheless, the effect of the rheological behavior of the polymer matrix is also a key parameter that has to be taken into account when evaluating the influence of the processing parameters in the cellular structure.
In this work, the effect of the rheological behavior of PMMA has been studied. Nanocellular PMMA has been produced by means of gas dissolution foaming process by using polymers with different viscosities. On the other hand, various processing conditions (saturation pressures and temperatures) have been tested. Finally, a relationship between the rheological behavior of the polymeric matrix and the density and cellular structure has been established allowing to control the final cellular structure by changing the properties of the solid matrix.