Crystalline morphology and crystallization characteristics of in-situ blends of anionic polyamide 6 with noncrystallizable semi-aromatic polyamide copolymer

A noncrystallizable semiaromatic polyamide copolymer(NSAP) was dissolved in molten caprolactam, and PA6/NSAP blends' were produced in-situ via the anionic ring-ppening polymerization of caprolarctam. The presence. of a single loss tangent(tan delta) peak measured by means of dynamic mechanical: analysis(DMA) proves the miscibility between PA6 and NSAP in the blends. It was found that there existed drastic changes in the crystallographic form and crystallization kinetics for the in-situ blends, e..g., when 20% NSAP was added, nearly all crystallites existed in the gamma form and the crystallization could hardly occur upon cooling even at a rate of 2.5 degrees C /min. Moreover, cold crystallization appears during the subsequent, heating and its melting point is 40 degrees C lower than that of the virgin system. On the other hand, the size of the spherulites only, decreases modestly. It is suggested that the introduction of irregular stiff segments originated from NSAP into PA6 macromolecule chain, which resulted from transamidation during the polymerization play a dominant role in the drastic change of crystallization kinetics and the resultant morphology of the in-situ blends.