Glass transition temperature measurement system

The invention relates to the field of material properties. More particularly, the present invention relates to the testing of the glass transition property of composite glass materials. A glass transition temperature Tg measurement system includes a probe point penetrating into a sample under test that has been heated by a heater to a temperature where the sample undergoes a phase change from a solid to a semisolid. A thermocouple is used to measure the temperature while a motion transducer is used to measure the amount of penetration. The penetration amount sharply increases at the glass transition temperature. A portable unit can be used in the field to test the Tg properties of various composite materials used, for example, in structures including buildings and bridges.