Crystallization behavior of sheared polyamide 66

The application of fast scanning chip calorimetry (FSC) for analysis of sheared polyamide 66 (PA 66) provided quantitative insight of the effect of shear flow and flow-induced formation of crystallization precursors/nuclei on the subsequent crystallization in a wide range of temperatures. In the high-temperature, heterogeneous-nucleation range, there is a direct relationship between the amount of specific work supplied to the melt and the acceleration of crystallization, presumably due in part to increased nucleation density of the sheared samples. This information is directly applicable to polymer engineering applications where the formation of crystalline domains during processing often occurs at rapid-cooling conditions. Analysis of the structure at the micrometer-length scale of sheared PA 66 by polarized-light optical microscopy (POM) revealed large shish-kebab structures.