|DSC - Differential Scanning Calorimetrydsc|
|Analytical technique description:||
Differential Scanning Calorimtry is a thermic method especially indicated for the study of transitions which imply specific heat variations and energy absorption (endothermic variations) or emission (exothermic variations). The sample is submitted to a controlled thermic scanning, giving back qualitative information about temperature of specific thermic phenomena and about their properties (endothermic or exothermic phenomena).
In Cultural Heritage field, this is an especially suitable technique to determine the temperature of some phase transitions that are particularly significant for polymeric materials to be used in conservation: glass transition temperature Tg, crystallization temperature Tc, melting temperature Tm. In particular, Tg indicates the temperature where a polymer changes itself from an amorphous (molten or rubber-like) state to a vitreous (hard and relatively brittle) state. This transition is then an important characteristic for all the amorphous polymers that are used in conservation: a material with a Tg that is lower than room temperature is soft and flexible, while a material having a Tg higher than room temperature is hard and brittle, and it can lead to cracks and fractures.
It is a thermoanalytical technique, in which information are given from the controlled heating or cooling of the studied material. In particular, Differential scanning calorimetry is based on the difference between the thermic flow of the sample and the one of a reference, both submitted to a controlled and preset temperature program. Differential measurement of the system is bond to the specific thermic behavior of the material, independently from experimental conditions.
|Instrumental details:||Perkin Elmer system, model Pyris 1, equipped with a criogenic system Pyris Intracooler II (Florence Unit).|