The master plots for the various model equations from Table are shown by the lines in Figure . For clarity only one representative mechanism function from each category (Dj, Fn, Ri, Am, Pn) was plotted, although all models were evaluated. For diffusion and geometrical contraction the kinetic equations for cylinders (D2, R2) are shown because the PA 6 filament precuts were cylinders. When comparing the experimental values with the model pre- dictions in Figure it was observed that the values of the microwave energy supply follow a trend best described by the model of a contracting cylinder (R2). The likely reason is that the cut PA 6 filaments are cylindrical. In the R2 model the shrinking reaction interface is the limiting step for the reaction rate after an initial rapidly occurring nucleation on the particle surface .