The falling weight impact properties of maleic anhydride compatibilized polypropylene-polyamide blends

A series of polypropylene polyamide 6 (PP-PA) blends of composition 80:20, 50:50 and 20:80 have been prepared in a twin screw extruder followed by injection moulding. Maleic anhydride grafted polypropylene was used as a compatibilizer for these blends. Static mechanical and falling weight impact tests were performed on these blends. The fracture surfaces of impact specimens were subsequently examined by scanning electron microscopy (SEM). The mechanical properties of the blends were found to be strongly dependent on the PP-PA blend ratios. The Young's modulus, tensile strength and impact energy were observed to increase with increasing PA content. The impact strength was better in blends when the PA content approached 80 wt %. SEM observations revealed that the addition of compatibilizer resulted in good adhesion between the PP dispersed domains and PA matrix in the PP-PA 20:80 blend. Furthermore, the SEM fractographs also indicated that the cold drawn of PA matrix and debonding of PP domains were responsible for the high impact strength of this blend.