抄録
In order to establish the various methods for measuring and evaluating the glass transition points of liquid crystalline polymers, a differential scanning calorimeter, thermomechanical analysis equipment and dynamic viscoelasticity measuring equipment were used to measure sample polymers for their glass transition points, thereby identifying any problems involved in the measurements. The measurement using a differential scanning calorimeter was found to be affected by the heat history of the polymer samples measured and their temperature raising/lowering rates, showing that it should be made using samples subjected to little heat by raising or lowering its temperature at a relatively high rate. In the measurement using thermomechanical analysis equipment, a sample polymer was heated continuously from room temperature to 200°C at a constant rate to measure its linear thermal expansion coefficient, which showed a change at its glass transition point. In this measurement, it is necessary to note that the sample is subject to melting and rapid cooling, has a directional property in its linear expansion coefficient and is subject to annealing, resulting in post-shrinkage. In addition, dynamic viscoelasticity measuring equipment was used to measure a sample polymer for its storage elasticity, loss elasticity and loss tangent, thereby evaluating its glass transition point. This measurement, which restricts the sample shape, requires the use of a sample subjected to a heating process to prepare it into a shape suitable for the measurement, causing its glass transition point to become higher with its elastic modulus affected by frequency and temperature to a considerably large extent. This suggested that it is important to make this measurement under properly set conditions.
