| Abstract: | The purpose of the work was to test existing theories of chain folded polymer crystallization over a supercooling range which is much is excess to what could be hitherto realized. This was made possible by the recognition that crystallization of isotactic polystyrene in solution could be conducted over an exceptionally wide range of temperatures in an isothermally controlled manner. The results revealed that the familiar inverse dependence of the fold length on supercooling (the behavior observed and studied in polyethylene) was only displayed at the lowest supercooling; at high supercoolings the fold length reached a constant lowest value unaffected by further lowering of the crystallization temperature. This is in conflict with present theories, which predict a catastrophic upswing in fold length at high supercoolings. It is demonstrated that the observations cannot be made compatible with this prediction by any conceivable adjustment of the numerical parameters. The implications of these findings are discussed. |
