Rheology and Properties of Thermotropic Liquid Crystalline Poly (Bisphenol E Isophthalate-Co-Naphthalate)

Thermotropic liquid crystalline (LC) copolyesters of Bisphenol E isophthalate-co-naphthalate compositions, have been characterized by a range of rheological and other properties. All LC copolyesters contained the same nominal ratio of comonomers, but differed in molecular weight. Properties have been compared and contrasted to those of a non-liquid crystalline Bisphenol E isophthalate polyester. Interesting features exhibited by the LC copolyesters are a (1) minimum in viscosity as a function of temperature, (2) pronounced shear thinning, (3) the absence of a Newtonian viscosity plateau at low shear, (4) an order-of-magnitude lower viscosity for a LC copolyester compared to the conventional polyester of similar apparent molecular weight and (5) much lower (perhaps even negative) extrudate swell.