A THERMOMECHANICAL ANALYZER WITH OPTICAL-DETECTION

A thermomechanical analyser with a simple and original detection system is described. The same device is used at the same time to exert a well determined traction on the sample and to measure its lengthening. A weight is hung at a end of a thin wire the other end of which is hooked at a end of the sample. The wire drives a pulley which bears a mirror. The rotation of a reflected laser beam is measured at 1/1000 degrees so that relative length variations of the sample lower than 10(-6) may be detected. The sample is set in a thermally regulated chamber the temperature of which may vary in a controlled way from -180 to 200 degrees C. The performances of the apparatus (sensitivity, accuracy and reproducibility) are presented and discussed for some characteristic examples, in particular on amorphous polymers for the study of which this device is essentially devoted.