POLYMER CRYSTALLIZATION DYNAMICS, AS REFLECTED BY DIFFERENTIAL SCANNING CALORIMETRY .2. NUMERICAL SIMULATIONS

With the aid of a model for the kinetics of polymer crystallization, a s put forward in previous publications, the shape of DSC-curves and th eir position on the temperature scale were simulated for various condi tions of heat transfer in the apparatus. It turns out that the outcome is very dependent on the assumptions made with respect to these heat transfer conditions. For the ideal condition - no temperature differen ces between sample, pan and furnace - an invariable shape is predicted for the DSC-curves. They only shift to lower temperatures with increa sing cooling rates. For more realistic conditions, the curves not only shift but become broader and their maxima decrease. They show a more familiar appearance. These calculations are very involved, however, A simple balance equation is shown to yield equivalent results, if a dim ensionless characteristic number like the Nusselt number remains consi derably smaller than one. This number contains an effective heat trans fer coefficient between sample and furnace which, surprisingly, should not be too high, Apparently, the heat capacity of the pan does not pl ay an important role under these conditions. This is investigated in A ppendix II, Appendix I describes the procedure of the numerical simula tions.