What are the factors affecting glass transition temperature in polymers?

Pressure and free volume 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 are the factors that affects glass transition temperatures?

Chain Stiffness-Stiffening groups: in the polymer chain reduce the flexibility of the chain and raise the value of Tg . poly(ethylene terephthalate) Tg=69oC.

  • Intermolecular Forces- Stronger intermolecular forces lead to a higher Tg.
  • Pendant Groups-
  • Cross-Linking-
  • Plasticizers-

    • What factors determine transition temperature?

    There are several factors which directly affect the phase transition temperature including hydrocarbon length, unsaturation, charge, and headgroup species.

    How does crystallinity affect Tg?

    Tg is definitely shown to decrease with increasing degree of crystallinity, an effect which tentatively is related to increasing free volume of the amorphous part of the polymer as the less dense crystalline phase increases and pulls apart the polymer chains in the amorphous regions. Tg is determined to be 14 ± 2°C.

    How does molecular weight affect Tg?

    Molecular Weight: In linear polymers, increase the MW leads to decrease in chain end concentration which results in decreasing free volume at end group region and increase in Tg.

    Does crystallinity affect Tg?

    Tg is definitely shown to decrease with increasing degree of crystallinity, an effect which tentatively is related to increasing free volume of the amorphous part of the polymer as the less dense crystalline phase increases and pulls apart the polymer chains in the amorphous regions.

    Does crystallinity affect glass transition temperature?

    It is shown that an increasing degree of crystallinity acts to raise the glass transition temperature of the polymer and reduce the overall degree of enthalpic relaxation. For an equal degree of crystallinity the glass transition temperature is also shown to be sensitive to isothermal crystallisation temperature.

    Why does molecular weight affect the glass transition temperature?

    Molecular Weight: In linear polymers, increase the MW leads to decrease in chain end concentration which results in decreasing free volume at end group region and increase in Tg. Molecular Structure: Existence of bulky, inflexible side groups increases Tg of material due to decreasing in mobility.

    What is the effect of chain flexibility on glass transition temperature?

    Aliphatic C-C and C-O bonds show quite flexibility while introduction of ringed structures causes stiffening of chain. Stiffening of chain causes increase in glass transition temperature therefore glass transition temperature of polyethylene terephthalate is higher than their aliphatic counterparts.

    What is glass transition?

    Obeikan Glass Co. holds almost 50% of the clear float glass market The company’s management is working on finalizing the required paperwork to transition to the main market. Q: Do you believe that the company’s stock was evaluated at a reasonable

    How is the glass transition temperature determined?

    Abstract. A simple and easy optical method is proposed for the determination of glass transition temperature ( Tg) of polymers.

  • Introduction. The glass transition temperature ( Tg) is one of the most important properties that define a polymer.
  • Materials and Methods.
  • Results.
  • Discussion.
  • Conclusions.

    • What is definition of glass transition temperature?

    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 does glass transition temperature mean?

    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. The DSC automatically plots a chart which you can calculate the approximate Tg from.