Effect of matrix graft modification using acrylic acid on the PP/Mg(OH)2 composites and its possible mechanism

The matrix graft modification using an acrylic acid (AAc) was employed on the polypropylene/Mg(OH)₂ flame-retardant composite. The graft modification of PP matrix was carried out via an in-situ reactive extrusion by a twin-screw extruder. The tensile strength of the composites was analyzed using an equation developed by Pukanszky from which both matrix tensile strength σ₀ and interfacial adhesion strength were found to be increased. The enhancement of σ₀ is due to the intermolecular crosslinking of PP by AAc grafting. This crosslinking causes increases of tensile strength, Young’s modulus, impact resistance, and thermal resistance, but decreases the elongation at break of the composites.