in the material obtained and the solvent dissolved in the supercritical fluid can be removed thereby however if the resulting product is found to be moist it may be desirable to remove the solvent by continuously purging the chamber with the fluid or by increasing the operating time or temperature the morphology of the porous material thus obtained is generally closed celled the porous polymeric product may have a porosity of about 89 to 98 with closed pores between about 50 and 250 u03bcm in diameter the porous biodegradable polymers with closed cell morphology are useful in controlled release drug delivery systems if interconnected pores are desirable the porous product obtained from the pressure reduction step is promptly heated to an elevated temperature in an oven this heating accelerates the evaporation of the fluid contained in the porous material the porosity is increased and the pore spaces are interconnected to form open cell morphology as a result the heating step is preferably carried out under conditions of about 150 u00b0 to 250 u00b0 c for about 1 to 20 seconds a highly porous product with a porosity of about 97 to 99 and with interconnected pores between about 50 and 250 u03bcm in diameter can be achieved the porous biodegradable polymers with open cell morphology are useful in a variety of tissue engineering applications such as three dimensional scaffolds for cell culture or media for cell and tissue culture to form artificial skins burn wound coverings haemostasis and so on the above and other objects features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention explained.