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Explain whether GLASS TRANSITION TEMPERATURE is exothermic or endothermic??????????

mohit yadav , 15 Years ago
Grade Upto college level
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Ritender Singh AskiitiansExpert-IIT

Differential scanning calorimetry (DSC) can be used to measure a number of characteristic properties of a sample. Using this technique it is possible to observe  glass transition temperatures Tg.

Glass transitions may occur as the temperature of an amorphous solid is increased. These transitions appear as a step in the baseline of the recorded DSC signal. This is due to the sample undergoing a change in heat capacity; no formal phase change occurs. As the temp increase solid wil become less viscous.At the same time molecule may obtain enough freedom of motion to spontaneously range themselves into a crystalline form.This is known as crystallization temperature.This transition from amorphous solid to crystalline is an exothermic process and result in the peak of DSC signal.As the temp increases the sample eventually reaches its melting temp.The melting process results in endothermic peaks in DSC signal.

Last Activity: 15 Years ago
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