A model recovery process for scrap polystyrene foam by means of solvent systems

A solvent technique is studied for the recovery of polystyrene (PS) foam waste. The model process proposed ensures removal of any impurities present and comprises dissolution of the starting material, filtering, reprecipitation, thorough washing of the polymer grains obtained and drying. The solvent mixtures involved are separated by distillation for re-use. The following criteria are considered: (a) the rheological behaviour of the PS solutions prepared, (b) the yield of the process of polymer of acceptable grain size and (c) sufficient solvent/non-solvent separation. On the basis of these criteria, methyl ethyl ketone/n-hexane or methanol and p-xylene/n-heptane are suggested as effective solvent/non-solvent systems.