How can the glass transition temperature of a polymer be decreased?

As stated before, plasticizers can decrease the glass transition temperature of the polymer. if you increase the free space between the chains molecules by adding a bulky Groups during polymerization process or increase the chain lingth of the side Groups or modifying the crystalline nature may reduces the Tg.

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.

On what factors does the glass transition temperature depends?

It is also defined as a temperature at which amorphous polymer takes on characteristic glassy-state properties like brittleness, stiffness and rigidity (upon cooling). This temperature (measured in °C or °F) depends on the chemical structure of the polymer and can therefore be used to identify polymers.

How can you increase the glass transition temperature of a polymer?

These can be done by controlling cooling rate and isothermal time during heat treament, and polymer modification, respectively. On the other hand, increasing pressure to polymer will also increas molecular crowing and interaction, resulting increased Tg.

What does a higher 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.

How does temperature affect polymers?

Higher temperatures lead to lower young modulus of the material. Weak points of every polymeric material are the secondary bonds between molecules of your polymer. With increasing temperatures, the molecules have more kinetic energy, thus the weak secondary bonds have less and less effect.

What does a high glass transition temperature mean?

What will happen when glass transition temperature increases?

1.7. At the glass transition temperature, the amorphous regions experience transition from rigid state to more flexible state making the temperature at the border of the solid state to rubbery state. It is also said that at this temperature the free volume (gap between the molecular chains) increases by 2.5 time.

What happens above 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 does a lower glass transition temperature mean?

At some point the heat energy is enough to change the amorphous rigid structure to a flexible structure. 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.

What is glass transition temperature What are the parameters affecting the glass transition temperature?

Molecular weight- GTT (glass transition temperature) is directly proportional to molecular weight of polymer. Flexibility- GTT is inversely proportional to flexibility. Plasticizer – GTT is inversely proportional to plasticization. Inter molecular force – GTT is directly proportional to intermolecular force.

What is glass transition temperature of polymers?

The glass transition temperature is the temperature range where the polymer substrate changes from a rigid glassy material to a soft (not melted) material, and is usually measured in terms of the stiffness, or modulus.

What is glass transition temperature of amorphous polymer?

When an amorphous polymer is heated, the temperature at which it changes from a glass to the rubbery form is named the glass transition temperature, Tg. A given polymer sample has multiple values of Tg because the glass phase is not at equilibrium.

What causes glass to become amorphous?

The impurity effect may cause a poor glass former to exist in the amorphous state in a multi-component formulation. Also, amorphous solids can result from solid-dispersion, a process used to enhance bioavailability, and solid-state chemical reactions (degradation) of crystalline precursors.

What is glass transition in thermodynamics?

Glass Transition. The glass transition is the phenomenon in which a solid amorphous phase exhibits more or less abrupt changes in derivative thermodynamic properties such as heat capacity or thermal expansion: when an amorphous material changes from a solid state to a liquid state on heating or from a liquid to a solid-like state on cooling.

What is the preparation of amorphous solids?

Preparation of amorphous solids The preparation of amorphous solids, for thermodynamic and kinetic reasons, is easy for some materials (good glass formers), but difficult for others (poor glass formers).

https://www.youtube.com/watch?v=5lH_Xt2KUjA