Effect of Polypropylene Percentage on Morphological and Mechanical Properties of Polybutylene Terephthalate/Polypropylene Blends

Polybutylene terephthalate (PBT) has a strong resistance to abrasion, deformation, and chemical resistance. However, how to further improve the impact toughness of PBT is still an issue that receives the attention of many researchers. This investigation aims to enhance its mechanical properties by mixing it with polypropylene (PP). The tensile strength, impact strength, flexural strength, and microstructure are accorded to ASTM D638, ASTM D256, and ASTM D790. In this analysis, PP was mixed with PBT with different ratios of 95/5, 90/10, 85/15, 80/20, and 75/25. Use injection molding technique to mold specimens for mechanical testing. The results show that the impact strength is 3.7, 6.6, 5.63, 5.2, 5.1, and 4.9 kJ/m², corresponding to 0, 5, 10, 15, 20, and 25% PP. The impact strength of PBT/PP blends is higher than neat PBT. Especially in the 5% PP sample, the impact strength increase can reach the highest level of 80.3% compared to neat PBT. The flexural strength tends to decrease with increasing PP content. After measuring, we get 77.9, 65.6, 62.2, 58.4, 58.2, and 54.0 MPa, corresponding to 0, 5, 10, 15, 20, and 25% PP. The microstructure of the blends showed that spherical PP particles were interwoven into the PBT substrate, but no interphase adhesion was observed. In general, selecting a suitable PBT/PP blend could improve the impact strength while preserving the tensile strength, allowing it to be applied widely.