Tensile and impact behavior of polypropylene/low density polyethylene blends

Blends of polypropylene (PP) and low-density polyethylene (LDPE) may contribute to make recycling more economically attractive. The aim of this work was to make PP/LDPE blends (0/100, 25/75, 50/50, 75/25 and 100/0 w/w) via injection molding carried out under various injection temperatures and to evaluate their tensile and impact properties. The blends yielded tensile stress-strain curves very dependent on their composition, especially regarding elongation at break and the presence of necking. An irregular behavior for the 50/50 w/w blend is reported. Nevertheless, a linear variation of the yield strength and elastic modulus with the blend composition was observed. The behavior of the blend was also very dependent on processing temperature. Addition of 25% of LDPE to the PP may result in similar degradation of its mechanical properties to that caused by a 10 °C processing temperature increase. Statistical analyses proved valuable when reporting results concerning blends.