Define glass transition temperature Why do we need to know t

Define glass transition temperature. Why do we need to know the glass transition temperature of polymers? Write down the glass transition temperature of Nylon, Polyester, and Polystyrene. Among the polymer listed which one would you select for high temperature application and why?

Solution

Glass transition temperature (Tg) is defined as the temperature at which the mechanical properties of a plastic / adhesive radically changed due to the internal movement of the polymer chains that form the plastic / adhesive.

In the study of polymers and their applications, it is important to understand the concept of the glass transition temperature, T_g. As the temperature of a polymer drops below T_g, it behaves in an increasingly brittle manner. As the temperature rises above the T_g, the polymer becomes more rubber-like. Thus, knowledge of T_g is essential in the selection of materials for various applications. In general, values of T_gwell below room temperature define the domain of elastomers and values above room temperature define rigid, structural polymers.

One of the most important properties that define a polymer (and hence to an adhesive) is its glass transition temperature, the value of the glass transition temperature is directly related to the mechanical properties (strength, hardness, brittleness, elongation...) that the polymer (adhesive/plastic) presents at the temperature that is exposed, you\'ve never seen in winter why some plastics become hard and brittle?, the explanation lies in its glass transition temperature.

GLASS TRANSITION TEMP OF NYLON 70 DEGREE CELSIUS

GLASS TRANSITION TEMP OF POLYESTER 80 degree Celsius

GLASS TRANSITION TEMP OF polystrene 90 degree Celsius

for high temperature application polystrene is used because it will always work in its glassy state properties resulting in low elongation and high resistance to stress.