Study of the change in polarity of polypropylene modified in bulk by polarcopolymers

The adhesive properties of the blends of isotactic polypropylene with ethyl ene-acrylic acid copolymers were investigated. It was found that the surfac e free energy, polar component of surface free energy, polar fraction and m echanical work of adhesion increased with concentration of EAA copolymers i n the iPP blends to a degree exceeding additive function. The proportionali ty of mechanical work of adhesion of the polymer blends to polar fraction t hat reflects the strength of adhesive joint was also revealed. This observa tion permits us to claim that the increase in polarity or hydrophilicity of iPP due to modification in bulk by the use of polar EAA copolymer raises t he strength of adhesive joints between iPP and more polar polymers. The rel ationship between mechanical properties of the studied polymer blends and t heir composition showed the functional additivity of the mechanical paramet ers. (C) 2001 Kluwer Academic Publishers.