What is the glass transition temperature of water?
What is the glass transition temperature of water?
about 136 K
Liquid water must be cooled to its glass transition temperature (about 136 K or −137 °C) in milliseconds to prevent the spontaneous nucleation of crystals.
How do you calculate glass transition temperature?
3.2. 1 Glass transition temperature. Glass transition temperatures of cyclic and linear PS were determined by DSC. For linear PS, the dependence of Tg on molar mass can be expressed by Tg = [1/Tg + K/Mw]−1, where K is a polymer-dependent constant and Mw is the weight average molar mass.
Why the glass transition temperature of polyamide is high?
PA6 belongs to the family of aliphatic polyamides. Its monomer has two polar groups; the amide and carbonyl groups. These polarities can form hydrogen bonds between chains, leading to high strength [1]. Therefore, it is clear that the glass transition temperature is an important parameter for PA6 properties.
What is the glass transition temperature of polystyrene?
100 °C
Forms produced
| Properties | |
|---|---|
| Glass transition temperature | 100 °C |
| Vicat softening point | 90 °C |
| Coefficient of thermal expansion | 8×10−5 /K |
| Specific heat capacity (c) | 1.3 kJ/(kg·K) |
What is the difference between glass transition temperature and melting temperature?
The main difference between glass transition temperature and melting temperature is that glass transition temperature describes the transition of a glass state into a rubbery state whereas melting temperature describes the transition of a solid phase into a liquid phase.
What factors affect 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.
What is the importance of glass transition temperature?
Glass transition temperature Tg is an important parameter used for identification of plastics. The Tg value is the temperature at which amorphous polymers change from hard to soft. The concentration of crystalline regions in amorphous (semicrystalline) polymers affects the rigidity of the polymer.
What are the factors affecting glass transition temperature?
What happens after glass transition temperature?
There is a certain temperature(different for each polymer) called the glass transition temperature, or Tg for short. When the polymer is cooled below this temperature, it becomes hard and brittle, like glass. Some polymers are used above their glass transition temperatures, and some are used below.
What happens below glass transition temperature?
What happens during glass transition?
The glass transition is a reversible transition that occurs when an amorphous material is heated or cooled in a particular temperature range. On cooling, the material becomes brittle (less flexible) like a glass, and on heating becomes soft.
What does a high glass transition temperature mean?
The polymer molecules move freely around each other. This transition point is called the glass transition temperature. The lower slope below the Tg is due to the lower heat capacity for the amorphous polymer. Above the Tg, the rubbery, flexible polymer has a higher heat capacity.