PREPARATION AND PROPERTIES OF A LIQUID-CRYSTALLINE SEGMENTED BLOCK COPOLYESTER

A segmented block copolyester with a liquid crystalline (LC) "hard block" and poly(tetramethylene glycol) (PTMG) "soft block" was prepared and characterized by intrinsic viscosity [eta], by gel permeation chromatography (GPC) for number average molecular weight and molecular weight distribution, by differential scanning calorimetry (DSC), and by dynamic mechanical thermal analysis (DMTA). The "soft block" had a melting transition at about -30-degrees-C and the hard block had a glass transition at about 70-degrees-C and a nematic-to-isotropic transition at 260-degrees-C. Mechanical testing, which included tensile testing, hysteresis analysis and stress relaxation at small strains, revealed that the block copolyester was a flexible rubbery material with an elongation at break of about 1000% and showed reversible extension below 50% strain.