The influence of viscoelasticity of elastomer on flow marks in injection molding of polypropylene/polyolefin elastomer/talc composites

Polypropylene/elastomer/filler composites are one of the most commonly used materials for spray-free automotive parts to meet the requirements of lightweight. However, its application is serious affected by the flow marks on the surface. Therefore, the reduction or elimination of flow marks defect is important to improve surface quality. In this work, polyolefin elastomer was slightly crosslinked to study its effect on flow marks. The results show that the slightly crosslinking significantly increases the elasticity of elastomer, which makes the melt flow more stable. Meanwhile, the enhanced elasticity is beneficial not only to resist shear deformation of elastomer, but also to recover from deformation during injection molding. As a result, the difference of dispersed phase morphology and surface gloss is reduced, and the flow marks defect is improved. The slightly crosslinked elastomer has little effect on the processability and tensile properties of composites, while the impact properties increase marginally.