What is the glass transition temperature width in polymer blends miscibility studies? Can I measure it from DSC?
Theoretically you can do it from DSC but in most cases the best way to measure Tg and its width is to use DMA and in particular the temperature dependence of the loss tangent. Dielectric spectroscopy is another way.
In order to measure the width of the glass transition from DSC you do need to analyze the derivative of the DSC signal versus temperature. For additional detail you may contact me.
Dear Mauricio Vásquez
In order to calculate the glass temperature width, you should differentiate (as a first derivative of DSC curve) using orgin7 program as follows
Analysis-calculus-differentiate. The drop (endo exothermic) of Tg will convert to peak, so you can determine the Full Width at Half Max. (i.e. the width of Tg width).
If you are interested in comparing the dynamics of glass transition in various systems (the breadth of the loss curve) you are on much safer ground if using the master curve approach by the superposition of isothermal curves of creep, complex modulus or dielectric data. Dielectric spectroscopy allows the easiest construction of such curves as a wide range of frequencies are available (from 0.0001 Hz to 100 MHz or eve higher). See e.g. http://www.novocontrol.de/
As I already mentioned and Gyorgy described in more detail DMA and dielectric spectroscopy are the best methods for this study. The problem with the DSC is that the method has a rather poor sensitivity and resolution for such a study. However, it works well for amorphous polymers such as atactic polystyrene. As the degree of crystallinity is increased the method becomes less and less reliable. Origin is an excellent tool for graphing and mathematical tricks, including differentiation. There is more about TG and DSC....
For the use of DSC to monitor the glass transition you may also check::
Polyethylene Oxide− Fullerene Nanocomposites
Authors: Nasar Ali, Dorina Chipara, Karen Lozano, James Hinthorne, Mircea Chipara
Publication date
2016/11/25
Journal
Applied Surface Science
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