Crucial process modifications were shown necessary to improve the economics of cryogenic grinding of flexible polyurethane (PU) foam. It is concluded that foam densification prior to cryogenic processing was essential to reduce insulation effects. In comparative studies of foam and densified foam, increasing the density to similar to 800 kg/m(3) resulted in dramatically reduced cryogen use and vastly improved output. Results indicated that cryogenic pulverization presents a significantly more economic solution than previously recognized. Particles produced by this method were added to foam formulations and effects of particle size and structure on compression properties and cell structure of resultant foams were studied. Particle sizes <100 mu m gave similar compression properties and cell size to virgin foam at up to 10 parts by weight on 100 parts of polyol, but cell structure and compressive properties showed increasing divergence as particle size and addition concentration increased. Studies of alternative uses showed that the PU particles showed promise as fillers in rigid PU foam formulations and suggested an extending or reinforcing action in natural rubber vulcanizates.