Mechanical and flow properties of blends of polypropylene and powder coating recyclates with and without addition of maleic anhydride

In this research, from 10% to 40% by weight of hydrolyzed powder coating recyclates were used as filler in polypropylene (PP). Firstly, PP and filler were dry-mixed and then, in order to get a homogeneous mixture, were extruded at 180°C. The resulting compounds were cooled and granulated, and by use of an injection molding machine at 180–200°C, standard tensile test bars were produced. Tensile stress, three-point bending strength, and izod impact strength of these specimens containing different types of filler and different filler concentrations were tested. The results are presented, and the effects of type and content of hydrolyzed powder coating waste on the mechanical properties of polypropylene are discussed. Also, the change in melt flow index of polypropylene as a function of filler content is analyzed. Furthermore, the bonding mechanism of filler and matrix material was examined by electron microscopy.