Semi-interpenetrating polymer networks were synthesized starting from polyurethane (PU) and epoxy maleate of bisphenol A (EMBA). Differential scanning calorimetry and swelling measurements showed good miscibility and the presence of the strong intermolecular interactions within the synthesized networks. The physicomechanical properties increased against PU to a maximum value with the increasing of EMBA content up to 12 wt % and then decreased with further increasing EMBA content. Generally, with exception of the elongation at the limit of elasticity, the mechanical properties improved very much under action of the UV radiation. (C) 2002 John Wiley & Sons, Inc.