Flow and mechanical properties of polypropylene/low density polyethylene blends

Two types of polypropylene (PP) of different melt flow index (MFI) were blended with a low density polyethylene (LDPE) in a screw injection machine, the flow and mechanical properties of the blends being investigated. For the higher MFI PP (PPH), the melt flow rate (MFR) of the blend being maximum at a blending ratio of 50/50, whilst for the lower MFI PP (PPL), the MFR of the blend increased with increasing wt.% of LDPE. Basically, the relationship between the mechanical properties, such as tensile strength and Young's modulus, and the composition of the blends was in agreement with a logarithmic mixing rule. For the dependence of the tensile necking behaviour of the blends versus the blending ratios, some differences were found between the PPH/LDPE blend and the PPL/PP blend.