Rheological and failure properties of polycarbonate/poly(butylene terephthalate) blends

Trans-esterification behavior of polycarbonate/poly (butylene terephthalate) (PC/PBT) blends was investigated during the melt mixing process. Rheological and fracture behaviors, and fracture morphology were also investigated as a function of PC/PBT blend ratio. Based on FT-IR and ¹H-NMR results, a trans-esterification reaction was confirmed to occur between PC and PBT during the melt mixing process. The melt index (MI) decreased with increased PC content, indicating the higher flow resistance of PC. The storage and loss moduli were increased by increasing the PC loading, and the PC/PBT blends were Theologically incompatible based on the Cole-Cole plot. The tensile property increased linearly with the increased PC content. However, the impact strength increased until 50 wt% of PC loading, notably around 30 ∼40 wt%, and then was levelled off at 50 wt%. Rough ridges were formed on the impact fracture surfaces above the 40 wt% of PC content, supporting the observed higher impact strength in this range.