lasisiirtymälämpötilan

Lasisiirtymälämpötila, often abbreviated as Tg, refers to the temperature at which an amorphous solid, such as glass or certain polymers, transitions from a rigid, glassy state to a more flexible, rubbery state. This transition is not a sharp melting point but rather a gradual change in the material's properties over a temperature range. Below the glass transition temperature, the material is hard and brittle, with limited molecular mobility. Above Tg, the polymer chains gain enough kinetic energy to move and slide past each other, leading to increased flexibility and ductility.

The glass transition temperature is a crucial property in material science and engineering, as it dictates the service temperature range for many amorphous materials. For instance, polymers used in everyday objects will behave differently depending on whether they are operated above or below their Tg. The exact value of Tg for a specific material can be influenced by factors such as molecular weight, degree of cross-linking, presence of plasticizers, and cooling rate during its formation. Techniques like differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) are commonly used to experimentally determine the glass transition temperature. Understanding Tg is vital for selecting appropriate materials for various applications and predicting their performance under different thermal conditions.