Semi-Interpenetrating polymer networks (IPNs) of polyurethane anionomers (IPU) with Polyvinylchloride (PVC) were synthesized and characterized by Fourier-transform infrared spectrophotometer (FT-IR), thremogravimetric analysis (TGA) and mechanical studies. The synthesized semi-IPNs were found to be compatible. The hydrogen bonding interactions and the thermal stabilities are discussed based on FT-IR analysis and thermogravimetric analysis (TGA). Tensile strength and hardness increase with increasing NCO/OH ratio and ionic content of the polyurethanes.