Rheological Properties of Liquid Crystalline Copolyester Melts. II. Comparison of Capillary and Rotary Rheometer Results

摘要: In an earlier paper capillary rheometer results were presented for two liquid crystalline copolyesters consisting of 60 mole % and 80 p‐hydroxybenzoic acid (pHBA) polyethyleneterephthalate (PET). this obtained by means cone‐and‐plate (CP) parallel plate (PP) attachments a Rheometrics Mechanical Spectrometer are compared with the data. particular, it is observed that over range conditions studied, viscosity data in CP PP agree those rheometer. Furthermore, there no dependence on geometric or dimensional factors as low molecular weight crystals under some conditions. Although still shear rate dependent rates 5×10−2 sec−1, shown stress relaxation experiments following cessation steady flow significant yield stresses exist. The primary normal difference (N1) pHBA/PET copo...