Influence of Compatibilizer and Additives on the Mechanical Properties of Polyethylene-Polystyrene Blends

Polymer blends were prepared based on three different types of LDPE (A.B.C) and polystyrene without or with compatibilizer (KRATON G-1652) and with the addition of a pigment Iriodin, for the improvement of the optical properties. The Brabender torque and the tensile properties of the polymer blends were determined, particularly, the yield stress σ _y , the ultimate tensile strength (e.g. the strength at break) σ _B and the ultimate elongation (elongation at break) ε _B . By factorial experimental design, factors A (proportion of LDPE/polystyrene) and B (proportion of compatibilizer) were found to be statistically significant while C (type of LDPE) has lower significance. The compatibilizer acts as a reinforcing agent in the polymer blend of LDPE and polystyrene, changing the stress-strain curve to a ductile behaviour, increasing the torque, σ _B and ε _B and decreasing σ _Y . Graphite, which is contained in LDPE-A, acts as a reinforcing agent. Iriodin does not act as a reinforcing agent in the polymer blend but leads to a decrease of σ _B , and to an increase of torque. It does not influence the stress-strain curve much. The appropriate amount of compatibilizer is determined to be up to 20%. Iriodin improves the optical properties of polymer blends and compensates for their inferior mechanical properties.