Effect of compositions and compatibilizer on the viscoelastic behavior of polycarbonate/acrylonitrile butadiene styrene blends

The effects of blend compositions of polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) with and without compatibilizers namely styrene maleic anhydride (SMA), a reactive compatibilizer and Elvaloy is a non-reactive co-polymer of ethylene and butyl acrylate (containing 25 wt % methacrylate) on the properties have been studied. The PC/ABS blends with varying amounts viz., 40, 50 and 60 wt% of ABS have been melt mixed with or without 5 wt% of SMA using Polylab twin screw extruder. The viscoelastic behavior of PC/ABS blends have been determined using dynamic mechanical analyzer (DMA). From DMA studies, it was observed that the storage modulus of compatibilized PC40S and PC50S are higher than those of the corresponding uncompatibilized blends at the same temperature. The storage moduli of PC50, PC50E and PC50S at 50 °C were 1076, 1276 and 1461 MPa respectively, indicating an increase in the extent of miscibility aided by SMA than Elvaloy for PC/ABS system. Further, the shift in T_g and peak broadening reveals partial miscibility. The experimental results were compared with the results predicted by Kerner model. It is evident that the peak corresponding to the transition in PC tends to broaden with a weak ABS peak in PC60S blend. It was observed that there was a good agreement between experimental data of E′ as well as E″ with data predicted by model in the transition region. It was observed that for PC/ABS (50/50) blend, the storage and loss modulus values predicted is higher than the experimental values. The same blend composition with SMA shows the values of the model is under predicted than the actual experimental values. The T_g of neat ABS was 114 °C and T_g of ABS in the blends were gradually decreased from 120 to 117 °C.