Effect of Melt Flow Modifier on Physical and Mechanical Properties of Polymer Composite Based on Recycled Polypropylene and Aluminosilicate Microspheres

During recycling, thermoplastics feature mechanical and thermal-oxidative degradation leading to a deterioration in performance of finished plastic products. The potential of bringing the secondary raw material to the standard to allow processing through introducing aluminosilicate microspheres and modifiers that improve MFI is considered. We studied rheological, physical, and mechanical properties of polymer composites based on recycled polypropylene filled with aluminosilicate microspheres in presence of stearic acid. Stearic acid is shown to increase melt fluidity, to improve mechanical processability, and to facilitate uniform distribution of particles made of aluminosilicate microspheres over the bulk of the polymer. The optimal concentration of stearic acid is 0.5 wt %. This is the concentration at which the MFI shows the maximum increase. Under these conditions, a decrease in tensile strength does not exceed 16% and samples demonstrate better resistance to dynamic impact without a significant change in elastic modulus characterizing rigidity of the material.