Morphology and properties of compatibilized ternary blends (nylon 6/a thermotropic liquid crystalline polymer/a functionalized polypropylene) processed under different conditions

Abstract

Relationships between the properties of ternary blends of nylon 6, a thermotropic liquid crystalline polymer (TLCP, poly(ester amide), 20 wt%) and a compatibilizer (maleic-anhydride-grafted polypropylene, MA-PP, 2 wt%) are studied under various processing conditions. The immiscible binary blend can be compatibilized by the addition of MA-PP. The compatibilizer provides extrudate surface stability, thus enabling high drawing. Strong elongational flow, which was not possible when maleic-anhydride-grafted ethylene-propylene-diene terpolymer was used as a compatibilizer, favors fibril development. The shear viscosity of the ternary blend is slightly lower than that of the binary blend. The morphology of the dispersed TLCP phase varies between droplets and oriented fibrils when the drawing is weak and is highly correlated with changes in tensile properties. The optimum die exit temperature (280 degrees C) provides a more uniform morphology and more fibril shapes which are associated with the increased tensile properties. The die exit temperature effect still exists when the draw ratio is high. In all cases, it is manifest that, whenever applicable, extension is a decisive factor in the deformation of the dispersed TLCP droplets, which is necessary for significant improvements in the mechanical properties. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.