Molecular weight effect, transition parameters

The ductile-to-brittle transition in PA has been studied as a function of (1) materials parameters, including matrix molecular weight (4), type of polyamide (5, 6), and type of rubber (7), and interface (3), and (2) morphological parameters, including rubber concentration (9), particle size (9), ligament thickness (9, 10), use of very small particles (5, 11), and particle distribution (2). When one of these variables is studied, other variables are often changed too. Only in experiments with large series can some idea of the effect of a variable be obtained. 

Calculate the critical molecular weight (Mcr), the glass transition temperature (Tg), and the activation energy for viscous flow (E oo) of the polymer, by using the methods described in this book. (The values used for Tg and E should be corrected to include the effects of the polymer molecular weight when Mn Mcr, as described in Section 6.C for Tg and above for Ep oo ) If experimental values are available for any of these input parameters (and especially for Tg), these values can be used instead of the calculated values to refine the calculations. 

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