Mechanical and tribological properties of polyamide 6 and high density polyethylene polyblends with and without compatibilizer

The structure and the mechanical and tribological properties of polyamide 6 (PA6) and high density polyethylene (HDPE) polyblends with and without the compatibilizing agent maleic anhydride propylene were studied. Polyplending was carried out in a modular intermeshing co-rotating twin-screw extruder. The blended materials were injection molded to provide the test samples. Polyblends with 20, 40, 60, and 80% polyamide 6 in high density polyethylene were obtained. The mechanical properties were studied in terms of the tensile strength, hardness and elongation-to-break. Friction and wear experiments were run under ambient condition in a pin-on-disk machine with the composite pin riding on the flat surface of a steel disk at a sliding speed of 1 m/s and under a normal load 19.6 N. It was found that the tensile strength of polyblends increased when polyamide proportion was more than 20 wt.% and hardness increased with any polyamide proportion. The coefficients of friction of all polyblends were lower than those of the polymers. The best polyblends for low coefficient of friction and high wear resistance were 60 wt.% PA6–40 wt.% HDPE and 80 wt.% PA6–20 wt.% HDPE. The wear behavior is explained in terms of the ability of the polyblends to form transfer film on the steel counterfaces.