Thermomechanical analysis of fibers

Thermomechanical analysis (TMA) is one of the most important thermal analysis techniques. TMA and thermodilatometry measure some dimension as a function of temperature. The difference between them is that thermodilatometry measures the dimensional changes when negligible load is applied to the sample, while in TMA the load may be significant. TMA for fibers is a frequently used thermal analysis technique, because it can measure the thermal shrinkage and shrinkage force when the temperature is being raised. In this chapter the comparison of shrinkage force is given for drawn, heat set and relaxed fibers, and the origin of shrinkage force is explained. Fibers in most cases are characterized by the coefficient of linear thermal expansion measured in the fiber axis direction. The use of the newest TMA technique, modulated temperature TMA is presented and it is shown how to use the Reversing Dimension Change for characterizing shallow and broad glass transitions.