Four different polymer stabilizers were synthesized from the salt derivatives of phosphinic acids (p-butoxyphenylcyclohexyl-phosphinic acid) and potassium, nickel, and two different grades of iron metals. The synthesized stabilizers were introduced into an industrial polycarbonate (PC) and their effects on the mechanical and thermal behavior of PC were investigated. The experiments were carried on following the introduction of the stabilizer into the polymer. The mechanical properties were sensitive to the amount of the stabilizer. Small amounts of potassium increased the breaking stress, the modulus of elasticity, and elongation at break of PC. On the other hand, nickel and iron increased the modulus of elasticity and decreased the breaking stress and elongation at break. The additives negatively affected the thermal properties. This deterioration was caused by the increase of molecular distance between the chains that led to the reduction of polar forces and increased the free volume of the polymer. Heat treatment increased the brittleness and reduced the breaking strength, ductility, and modulus of elasticity of modified PC. (c) 2007 Wiley Periodicals, Inc.