The Effect of Blending Ratio on the Structure and Properties of the PPR/PS In situ Fiber Reinforced System Prepared by Multi-Flow Vibration Injection Molding

To enhance the mechanical properties of polypropylene random copolymer (PPR), polystyrene (PS) with four different contents were added to the PPR matrix through melt blending. Subsequently, using the Multi-Flow Vibration Injection Molding (MFVIM) technology, PPR/PS in situ microfiber composites (MFC) with different blending ratios were prepared. The results indicated that blending ratio had a great impact on the phase morphology and crystal structure of MFVIM samples, which was different from those of conventional injection molding (CIM) samples. PS ultrafine fibers could be formed under the shear field and could absorb the PPR molecular chains to form hybrid shish-kebab structures. Meanwhile, the PPR matrix could also form shish-kebab structures under the effect of strong shear. When the PS content reached 20%, under the combined action of PS in situ microfibers and highly oriented crystal structure, the tensile strength and Young’s modulus of the sample were obviously improved and the impact strength remained at a relatively high level. So a strong and tough balanced PPR based material was obtained. These results provide valuable insights for expanding the industrial and daily-life applications of PPR and show promising development prospects.