Rheological properties of PET/PC immiscible polymer blends: Effect of catalysts and stabilizers

The rheology of PET/PC blends obtained by melt reactive blending using various transesterification catalysts has been measured in the melt at 260 degrees C in dynamic oscillatory shear flow. The thermal stability in the melt of PET/PC blends is a key limitation of the measurement time especially in presence of transesterification catalysts. For long residence time, a noticeable decrease of the viscosity is observed. This decrease is attributed to thermal degradation promoted by exchange reactions. The efficiency of phosphite and phenolic stabilizers, alone or in combination, has been assessed from the rheological measurements. The results show that the effectiveness of phenolic species is more important than that of phosphites. The addition of 0.3 wt-% of Irganox 10 10 delays the decrease of the rheological characteristics for 10 minutes.