Influence of nucleating agent on the mechanical and thermal properties of neat isotactic polypropylene/reprocessed polypropylene blends

Abstract

In recent years, recycling of polypropylene (PP) has gained significant attention for various industrial applications, namely post-industrial PP waste has great advantages in terms of circular economy. In this study, the effect of the amount of nucleating agent on the mechanical and thermal properties of polypropylene blends was investigated. Neat isotactic polypropylene and reprocessed polypropylene (iPP/rPP) were blended by means of a twin-screw extruder at 0/100, 50/50, 25/75 and 100/0% (by weight), respectively. The blends were processed by means of a twin-screw extruder then injection molded with the nucleating agent at different ratios (0, 1, 3 and 6% by weight). The properties of the samples were investigated by melt flow index (MFI) measurement, scanning electron microscope (SEM), tensile test, three point bending test and differential scanning calorimetry (DSC) analysis. The MFI values of the blends increased with the increasing amount of rPP. As a result of DSC analysis, the melting temperature of the blends increased by 1.4 degrees C with the presence of 6% (by weight) nucleating agent. The highest flexural modulus was obtained as 1863 MPa for the iPP/rPP0 blends with the addition of 6% (by weight) nucleating agent. The elastic modulus increased with the addition of nucleating agent from 1819 (iPP/rPP50NA0) to 2152 MPa (iPP/rPP50NA6). The iPP/rPP blend with a weight ratio of (50/50) exhibited mechanical and thermal properties similar to neat iPP with the presence of 3% (by weight) nucleating agent.