Properties of blends of polycarbonate and a thermotropic liquid crystalline polymer

Abstract

Thermal properties, morphology, and Theological properties of the blends of polycarbonate (PC) and a thermotropic liquid crystalline polymer (LCP) prepared by screw extrusion have been investigated by differential scanning calorimeter (DSC), scanning electron microscopy (SEM), polarized optical microscopy, and rotational rheometry. From the measured glass transition temperature (Tg), the LCP appears to dissolve more in the PC-rich phase than does the PC in the LCP-rich phase. The polymer-polymer interaction parameter (χ12) and the degree of disorder (y/x1) of LCP were investigated using lattice theory in which the anisotropy of LCP was considered. The polymer-polymer interaction parameter (#12) were determined and found to be 0.068 for the extruded blends of PC-LCP (5 : 5) at 523 K. Significant depression of the viscosity is observed in the PC-rich blends and this is mainly due to the fibrous structure of the LCP in the blends. The storage modulus of the PC-rich compositions exceeds that of the matrix component at low frequencies and this result may be due to the increase of elasticity of the blends.