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

This work describes the effect of solvent precipitation on the crystal lization behavior and morphology of nylon 6,6. We found that solvent p recipitation of nylon 6,6 induces elevated crystallization temperature s 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 prima ry techniques used to characterize these changes in crystallization be havior and morphology were differential scanning calorimetry (DSC), po larized optical microscopy (POM), and wide-angle X-ray scattering (WAX S). Several other supplementary techniques were employed for identifyi ng the origin of the crystallization behavior and morphological change s after solvent precipitation. Our results are consistent with the hyp othesis in which dissolved nylon reorients to form ordered H-bonded re gions that later serve as nucleation sites during melt processing. Fin ally, T(mc) decreased with nylon 6,6 solution concentration prior to p recipitation. These results suggest that polymer entanglements in solu tion also affect the crystallization behavior and morphology of the so lvent-precipitated nylon 6,6. (C) 1994 John Wiley & Sons, Inc.