The morphology and properties of ternary blends of polyamides, a thermotropic liquid crystalline polymer and a compatibilizer

Abstract

Relationships between the properties of ternary blends of polyamides, a thermotropic liquid crystalline polymer (TLCP) (poly(ester amide)) and a maleic anhydride grafted polyolefin are studied under various processing conditions. Thermal properties show the compatibility in the ternary blend. The shear viscosity of a ternary blend is slightly lower than that of a 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. Though there are some morphological differences depending on the matrix thermoplastics (nylon 6, nylon 66 or nylon 46), it is commonly observed that addition of the compatibilizer induces better adhesion at the interface as well as lower interfacial tension, and hence enables the deformation of the dispersed phase into elongated and fibril shapes, even when the viscosity of the TLCP is much lower than that of the matrices. Fibril development is favored in the strong elongational flow which was possible because the compatibilizer stabilizes the extrudate. In all cases, it is manifest that, whenever applicable, extension is a decisive factor for TLCP fibril formation that is necessary for a significant improvement in tensile modulus and strength. There exists, however, an optimum compatibilizer amount and optimum die exit temperature, both of which provide more uniform morphology and more fibril shapes which contribute to enhanced tensile properties.