Synthesis And Characterization Of Thermotropic Liquid Crystalline Polyamide As Well As Theoretical Calculations

New thermotropic liquid crystalline polyamides were prepared from polyethyleneglycol bis(4-caroxylhenyl)ethers(PEG3) and p-phenylenediamine by using solution condensation method at a relative low temperature. The thermotropic nematic liquid crystalline behaviour of the polyamides was characterized by polarizing microscope, X-ray diffraction (SAXD, WAXD) and DSC, and some significant results were drawn.The results showed that nematic liquid crystalline mesophase was obtained when the temperature decreased, and was confirmed by the second endotherm corresponding clearing temperature of DSC curve as well as SAXD, WAXD curves. In order to develop the applications of the polyamides as engineering plastics besides as fibers, the specimen for tensile was manufactured and observed under SEM.All sorts of curves that the melting and clearing temperature of liquid crystalline polymers versus the components of the polymers were investigated using the sub-cluster statistics theory, and were concluded that there are eight kinds of curves of the melting or clearing temperature. The inherent factors which determined the melting and clearing temperature of the polymers were Ra and Rb, which was related to the length of the flexible spacers, the substituent of phenyl or biphenyl, and the components of the copolymers.