Rheological behavior and prediction for blending conditions of a thermotropic liquid crystalline polyester with nylon

Abstract

The dynamic rheological behavior of a liquid crystalline polymer (LCP), Vectra(TM) A, and nylons was investigated. The viscosities of nylon 66 and nylon 6 decrease slowly with an increase in temperature, while the viscosity of Vectra A drops dramatically at 280°C, but remains slightly changed above 300°C. At constant frequency and above 300°C, the mean value of the activation energy of Vectra A is about 87.0kJ/mole, but jumps to a much higher value of about 407.0kJ/mole if the melt temperature is below 300°C. The activation energy of Vectra A above 300°C is lower than nylon 66, which shows that the viscosity of nylon 66 has a greater temperature dependence than Vectra A. The viscosity ratio of Vectra A to Nylon 66 is less than 1 at temperatures higher than 290°C, which indicates that Vectra A can form the fibrils in the nylon 66 matrix and reinforce nylon 66 when blending them above this temperature. Experimental data confirm our prediction. Copyright (C) 2000 John Wiley and Sons, Ltd.