Instrumentation of TMA

A schematic diagram illustrating a typical thermomechanical analyzer is shown in Fig. 4.146. This instrument was produced by the Perkin-Elmer Co. Temperature is controlled through a heater and the coolant at the bottom. Atmosphere control is possible through the sample tube. The heavy black probe measures the position of the 

Thermomechanical analyzers are available for temperatures from as low as 100 K to as high as 2,500 K. Basic instruments may go from 100 to 1,000 K with one or two furnaces and special equipment for liquid Nj cooling. For higher temperatures. 

The graphs at the bottom of Fig. 4.147 display results gained in the flexure mode under conditions that satisfy the ASTM (American Society for Testing and Materials). The deflection temperature is taken where the sample has been deformed by 0.010 in 

Drawing causes higher orientation of the fiber, as is illustrated by Fig. 4.149. At the glass transition much larger shrinkage is observed than in Fig. 4.148. Subsequent crystallization occurs at lower temperature due to the better prior orientation. Since the DTA crystallization peak is smaller than the subsequent melting peak, one would conclude that the origin drawn sample was already somewhat crystalline. 

Annealing the drawn fiber, as shown in Fig. 4.150, introduces sufficient crystallinity to cause the shrinkage to occur continually between the glass and melting temperatures. One would interpret this behavior in terms of the existence of a rigid amorphous fraction that gradually becomes mobile at temperatures well above the 

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