Preparation and structure study of polypropylene/polyamide-6 gradient materials

A polymeric gradient material was prepared by a specific extruding technique in which the weight ratio of two components, polypropylene (PP) and polyamide‐6 (PA6), was changed gradually with the progress of process. This columnar gradient material was formed during a combined extruding and winding operating. The gradient variation of specimens sampled along the radius of columnar gradient material was confirmed and characterized through measurements of DSC melting behavior and elemental analysis. The morphological variation was studied using SEM observation. The results indicate that the content of either polymer shows a monotonous variation along the radius direction. With increasing radius, a gradually decreased percentage of PP was observed, whereas PA6 gradually increased. SEM photographs of the specimens sampled at different radii exhibit that the morphology also evolves gradually with variations in the percentage ratio of two polymers. A phase‐inversion phenomenon was recognized in this polymeric gradient material and a “dual mode” of dispersed morphology was found in the sandwich zone. These results indicate that the PP/PA6 blend with gradient structure was successfully prepared by use of this unique technique. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2491‐2496, 2004