Glass Transition of a Liquid Crystal Polymer

A commercially available liquid crystal polymer system having a very weak glass transition is investigated in order to illustrate the special problems of measurement and interpretation inherent in high-sensitivity T{sub g} measurement. Differential scanning calorimetry, thermomechanical analysis, and dynamic mechanical analysis were employed over the temperature region from ambient to 175 C. A transition between 75 and 125 C with a midpoint around 100 C was detected by most techniques. The use of the maximum in the derivative of the measured signal as the primary assignment of the glass transition temperature is recommended. The results are discussed with reference to other literature on this polymer system.