What is the glass transition temperature Tg?
Glass Transition Temperature (Tg) is the point at which a material alters state – going from a glass-like rigid solid to a more flexible, rubbery compound. Tg is normally measured on a Differential Scanning Calorimeter (DSC) piece of whizzy equipment.
How do you calculate the Tg of a polymer?
Tg is typically calculated by using a half-height technique in the transition region. The heating rate and sample heat history are a couple of factors that may affect the test result. Depending on the equipment capability, DSC can be used for a wide range of thermoplastic and thermoset polymers.
What is the difference between Tg and TM?
The terms TG (or Tg) and TM (or Tm) give two important parameters of polymers. These are temperatures at which the texture of polymer changes. These values are characteristic features of polymers. TG refers to the glass transition temperature whereas TM refers to the melting temperature.
Which substance lowers the temperature of the glass transition?
Hard plastics like polystyrene and poly(methyl methacrylate) are used well below their glass transition temperatures, i.e., when they are in their glassy state.
What is glass transition temperature discuss the factors which affecting the glass transition temperature?
Increase in pressure of surrounding leads to decrease in free volume and ultimately high Tg. Other factors like branching, alkyl chain length, bond interaction, flexibility of polymer chain, film thickness etc. also have significant impact on glass transition temperature of polymers.
Why glass transition temperature is determined?
Why is the Determination of Glass Transition Temperature so Important? The glass transition provides information about molecular dynamics in the supercooled melt. It defines the upper temperature limit for the use of solid amorphous materials; for rubbery materials, it is the lower temperature limit.
How do you determine the glass transition temperature Tg What is the difference between Tg and the melting temperature Tm why they are different?
The key difference between TG and TM polymers is that the TG of polymers describes the conversion of the glassy state into rubbery state whereas the TM of polymers describes the conversion of the crystalline state into an amorphous state. These are temperatures at which the texture of polymer changes.