SYNTHESIS, PROPERTIES AND PROCESSABILITY OF A NEW CLASS OF SEMIRIGID LIQUID-CRYSTALLINE COPOLYESTERAMIDES

A new family of semirigid main chain liquid crystalline polymers (LCPs ), referred to as SBAN, characterized by fairly good processability an d mechanical properties, and improved thermal resistance, have been sy nthesized by the melt polycondensation of sebacic acid (S), 4,4'-dihyd roxybiphenyl (B), 4-aminobenzoic acid (A), and 2-hydroxy-6-naphthoic a cid (N), in a wide range of compositions. The molar concentration of t he A and N units, in these LCPs must be kept lower than ca. 40 and 60% , respectively, in order to avoid the formation of homopolymeric block s, which impair spinnability. The presence of A units grants the forma tion of hydrogen bonds between neighboring macromolecules, and this le ads to higher tensile moduli and improved thermal resistance, with res pect to analogous semirigid LC polyesters.