As a novel toughening agent, thermotropic liquid crystalline polymers (TLCPs) possess excellent properties of high strength, high
modulus, lowexpanding coefficient, and high thermal stability. In this study, a thermotropic liquid crystalline poly(ester-imide) derived
from N,N’-hexane-1,6-diylbis(tri-millitimide) (IA6), p-hydroxylbenzoic acid (PHB), and 4,4’-dihydroxybenzophenone (DHBP) was
synthesized by the Higashi’s direct polycondensation method. The structure and properties of the TLCP were studied using Fourier
transformed infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetic analyses (TGA), polarized
light microscopy (POM), and wide angle X-ray diffraction (WAXD). The results revealed that the synthesized polyester-imide is a
nematic TLCP with good thermal stability and its starting decomposition temperature is up to 439?C. Additionally, polymer blends
of phenol-formaldehyde (PF) resin with different contents of polyester-imide were prepared and characterized by POM andWAXD.
POM results demonstrated that two-step blending is an ideal method for blending TLCP and PF resin. By this method, continuous
filamentous stripes can be clearly observed at 230?C for TLCP/PF blend of 10 wt% poly(ester-imide).