Effects of viscosity ratio and compatibilizers on the morphology and mechanical properties of polycarbonate/acrylonitrile-butadiene-styrene blends

A comprehensive experimental study was carried out to investigate the effec ts of 1) viscosity ratio, 2) temperature on the viscosity ratio, 3) extrude r screw location,. and 4) compatibilizers on the morphology of bisphenol-A- polycarbonate/acrylonitrile-butadiene-styrene (PC/ABS). Blends were prepare d by utilizing a co-rotating twin screw extruder and in-situ morphology obt ained via the screw pullout technique. A plot of the PC/ABS viscosity ratio , eta(PC)/eta(ABS), versus the shear rate showed a gradual rise in the curv e up to a critical shear rate and thereafter displayed asymptotic character . Contrary to premise, eta(PC)/eta(ABS) decreased with increasing temperatu re. This was elucidated by the melt viscosity of PC being thermally more se nsitive than ABS over the temperature range investigated. As expected, the plot of the average domain size versus the viscosity ratio gave a concave u p curve with a minimum when the viscosity ratio was close to unity. The mor phology evolution along the screw of a twin screw extruder was examined. Wh en sections of the kneading block were examined, the minor phase domains gr adually showed reduction in size toward the extruder die, and the smallest domain was realized at the end of the block, namely, the flow impeding left -handed screw element. Polymethylmethacrylate (PMMA) exhibited the greatest ABS domain size reduction, and annealed samples showed that it suppressed coalescence.