Solid state features and mechanics properties of PEI/PBT blends

Extrusion-blended and injection-molded PEI/PBT blends were found to be misc ible whatever the composition. The processability of the blends clearly imp roved with the presence of PET. The melt pressure at the exit was seen to b e a parameter as representative of the processability of the blends as the torque of blending. In the blends with 80 and 90% PET, a positive volume of mixing and the maintenance of the crystallinity of PET were seen. However, in the rest of the blends, negative volumes of mixing and important decrea ses in the crystallinity of PET were found. These solid state features gave rise to a ductility similar to that of the pure PEI and to a synergism of the modulus of elasticity and of the yield stress in the 90/10 and 80/20 bl ends such that the values were higher than those of either of the pure comp onents. (C) 2001 John Wiley & Sons, Inc.