lasisiirtymälämpötila

Lasisiirtymälämpötila, often abbreviated as Tg, refers to the temperature at which an amorphous solid, such as glass or certain polymers, transitions from a hard, brittle, glassy state to a softer, more pliable, rubbery state. This transition is not a sharp melting point like that of crystalline solids, but rather a gradual change in physical properties over a temperature range. Below Tg, the material behaves like a solid with limited molecular mobility, while above Tg, the polymer chains gain enough kinetic energy to move past each other, allowing for deformation.

The lasisiirtymälämpötila is a crucial property in material science and engineering, as it dictates the operating temperature range for many materials. For instance, polymers used in packaging or structural components must have a Tg above their intended service temperature to maintain their rigidity. Conversely, for applications requiring flexibility at low temperatures, materials with a low Tg are preferred. Factors such as molecular structure, chain entanglement, and the presence of plasticizers can significantly influence a material's Tg. It is determined experimentally through various thermal analysis techniques, including differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA).