MORPHOLOGY-PROPERTY RELATIONSHIPS IN ABS PET BLENDS .1. COMPOSITIONALEFFECTS/

Novel blends of PET and ABS were prepared by extrusion and injection m olding. DSC and DMTA studies show that PET and ABS are immiscible and that the blends consist of four phases: SAN, grafted polybutadiene, am orphous PET, and minor amounts of crystalline PET. The morphology was investigated by transmission electron microscopy on OsO4-stained and u nstained sections and by scanning electron microscopy of alkali- and s olvent-etched surfaces. These techniques reveal that the two major dom ains, SAN and amorphous PET, interpenetrate and are cocontinuous over the compositional range of 30-70 wt % PET. The yield stress and flexur al modulus increase in an almost linear fashion as the weight fraction of PET in the blend is increased. In contrast, the notched Izod impac t energy passes through a maximum and the Dart impact energy shows a s tep transition at 50 wt % PET. SEM studies of the Izod fracture surfac es exhibit considerable plastic deformation in both domains when the s pecimens are tough, indicating that both phases participate in the tou ghening process. (C) 1996 John Wiley & Sons, Inc.