MELTING AND RECRYSTALLIZATION OF PA-6/PA-66 BLENDS

The morphology of a number of polyamides (PA) -namely, PA-66, PA-6 / PA-66 blends, and PA-6/PA-66 copolymers-prepared from HCOOH solution and from the melt has been examined as well as the effect of annealing. In the blends, the PA-6 crystallizes within the PA-66 spherulites. When prepared from HCOOH solution at 25-degrees-C, the PA-66-containing samples show a large exothermic peak before the sample melting peak is observed by DSC. This exothermic peak, which cannot be fully explained by previously known observations, PA recrystallization, and/or the morphology changes we describe here, is not seen for PA-6 or for PA-66 prepared from HCOOH solution at 100-degrees-C. (C) 1993 John Wiley & Sons, Inc.