How do I calculate the ideal glass transition temperature (T0) values for a polymer using a measured glass transition temperature (Tg) and VTF equation
Is there any method instead of taking ideal glass transition temperature is roughly 50K below Tg?
You can do it by trial and error, checking the fit of temperature shift data or you can do nonlinear fitting. (The latter is more elegant and provides error data too).
Let {Y,T} be a set of data where Y = viscosity or DR time. Using Tg as a reference temperature, the VFT equation reads: Ln Y= A(Tg)+B(Tg)/(T-Tg). Using To as a reference temperature, the VFT eq reads: Ln Y = A(To) +B(To)/(T-To). Using non linear fitting of your data, you should be able to extract To.
To improve the mechanical properties of polymer, it can be employed plasticizers. Many brittle polymers are toughened by change its glass temperature (Tg) lower or near room temperature . It can be measure Tg by Differential Scanning Calorimetry DSC and DMTA
DSC might be easier measurement: differential scanning calorimeter. The experiment is straightforward. To lower Tg add a compatible small molecule or material with lower Tg..This would be called a plasticizer. The couchman equation may help in estimating amount to be added or it can be done empirically by preparing mixtures of different vcompositions. If, though the two are not compatible/miscible not much will happen.
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