Low-density microcellular polystyrene foams: Thermally stimulated liquid-solid phase decomposition

Low-density microcellular foams with an apparent density of 0.012-0.060 g/cm(3) and average pore size of 1-35 mu m were prepared by thermally stimulated liquid-solid phase decomposition of the system polystyrene-benzene with predominant freezing-out of the solvent. The character of the phase decomposition stipulates the formation of fibrous anisotropic structure. The density of foams and the pore size can be varied in wide ranges by varying the concentration of the initial solutions and the freezing rate. The freezing rate is a critical factor that controls the quality of the obtained foams; when the freezing rate is higher than the critical value, foams with poor properties are obtained.