Abstract: Conventional polyurethane foam products are modified by incorporating into the urethane reaction mixture a junction modifying particulate material that is selected with a critically controlled particle size relative to certain dimensional parameters of the foamed polymer matrix. This particulate material is selected with a particle size that results in location of the material in the foam cell wall junction regions rather than in the cell walls. The resulting products provided excellent physical properties (such as modulus of compression, tensile strength, elongation and tear resistance) at lower costs than normally encountered with similar unmodified foams. The preferred junction modifying particulate materials are organic polymeric materials such as ground rubber or plastics. As a result, the large particle size materials needed to achieve the junction modifying properties can be used without causing harmful abrasion or wear of processing equipment surfaces.