Novel thermotropic liquid crystalline polymers (TLCP) with improved processability and lower cost than Vectra((R)) were synthesized by esterification and melt polycondensation. Aromatic compounds, 6-hydroxyl-2-naphthoic acid, 2,6-naphthlenedicarboxylic acid, 4-hydroxybenzoic acid or terephthalic acid, were used as polycyclic stiff rod-like mesogenic groups. Aliphatic diol, ethylene glycol or 1,4-butanediol was used as flexible spacers to form semi-flexible main chain TLCP. The LCP products were characterized by FT-IR and H-1 NMR to identify their chemical structures. The analytical results showed the polymers had inherent viscosities of 0.35-0.54 dL/g. The crank shaft structure of the naphthalene decreased the melting temperature (T-m) of LCP (181-272 degrees C) to facilitate extrusion or injection molding, and maintained relatively high heat deflection temperature for high performance engineering plastics applications. The 5% weight loss decomposition temperatures were above 400 degrees C. LCPs have good solvent resistance and low hygroscopicity. The SEM morphology showed strong orientation on the surface in the flow direction and many micro-fibers structure in a sectional drawing. The optical textures of polymers observed by POM revealed a strong birefringence in the melts and indicated that they form nematic mesophase. All polymers have broad mesophase temperature (Delta T-meso) ranges. (c) 2005 Elsevier Ltd. All rights reserved.