EFFECT OF METALLOCENE ELASTOMERS AND SCREW SPEED ON POLYPROPYLENE COMPOUNDS: MORPHOLOGICAL AND PHYSICAL PROPERTIES

Abstract

Polypropylene (PP) which is widely used in automotive industries can replace engineering plastics and metals due to its outstanding mechanical properties, moldability and reduced weight. Some automotive parts such as bumper require higher impact resistance, which is the limited property of PP. The aim of this work is to improve the impact properties with balancing the stiffness-impact properties and the physical properties by blending PP with metallocence elastomer (POE) using a twin screw extruder. The effects of PP and POE type and blending ratio on the PP/POE blends properties and morphology was studied. The results showed that the impact strength of PP/POE blends increased with increasing POE content. However, the balancing of stiffness-impact properties and the physical properties of PP/POE blends were achieved at blending ratio 70:30, especially the well dispersed EOR in PP matrix. In addition, a continuous phase of homopolymer PP (H-PP) as stiffness material could provide the better balancing stiffness-impact properties than copolymer PP (C-PP). Furthermore, the screw speed (400-600 rpm) of extruded affected physical properties, the impact properties increased with decreasing screw speed. From the morphology of blends, an average particle area and aspect ratio of rubber particle in PP/POE blends had a pronounced effect on the physical properties of blends. The PP/POE blends at H-PP/EOR of ratio 70/30 exhibited the good balancing of stiffness-impact properties and physical properties and had a potential to be used as automotive bumpers.