EFFECT OF SOLVENT PRECIPITATION ON THE CRYSTALLIZATION BEHAVIOR AND MORPHOLOGY OF NYLON-6,6

This work describes the effect of solvent precipitation on the crystallization behavior and morphology of nylon 6,6. We found that solvent precipitation of nylon 6,6 induces elevated crystallization temperatures upon cooling from the melt (T(mc)) and highly nucleated morphologies that rival those induced by rapid, thermal reprocessing such as melt reextrusion or heterogeneous nucleating agents such as CaF2. The primary techniques used to characterize these changes in crystallization behavior and morphology were differential scanning calorimetry (DSC), polarized optical microscopy (POM), and wide-angle X-ray scattering (WAXS). Several other supplementary techniques were employed for identifying the origin of the crystallization behavior and morphological changes after solvent precipitation. Our results are consistent with the hypothesis in which dissolved nylon reorients to form ordered H-bonded regions that later serve as nucleation sites during melt processing. Finally, T(mc) decreased with nylon 6,6 solution concentration prior to precipitation. These results suggest that polymer entanglements in solution also affect the crystallization behavior and morphology of the solvent-precipitated nylon 6,6. (C) 1994 John Wiley & Sons, Inc.