Process-control parameters from time-temperature superposition

5 Process-control parameters from time-temperature superposition 

The principle of time-temperature superposition is that there is a temperature-shift factor that allows all data to be plotted on a master curve. This presupposes that there is no change in mechanism during the reaction, so that Equation (3.8) applies (Prime, 1997b). Such superposition processes are regularly used in rheology and the WLF equation is routinely applied when the system is above temperature Tg. When the system is controlled by 

In this the way the effect of the rate of temperature ramping may be taken into account in the total cure profile. In such studies the empirical E data may be adequate, but for detailed kinetic modelling it is generally recognized that isothermal experiments are appropriate, and even they may have limitations, as discussed later. 

In one of the earliest analyses of cure kinetics by DSC, Horie et al. (1970) derived a kinetic relationship for epoxy-amine cure assuming near-equal reactivity of primary and secondary amines and no other reactions. This was later refined for a stoichiometric epoxyamine system (Sourour and Kamal, 1976) and takes the form 

while there is a fit, the equation can have no physical meaning regarding the kinetics of the system. This approach has been modified by introducing a separate exponent, /, for the uncatalysed reaction  

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