Mechanical, rheological, and thermal behavior assessments in HDPE/PA-6/EVOH ternary blends with variable morphology

The mechanical, rheological, and thermal properties of various binary and ternary blends based on polyamide 6 (PA-6), high-density polyethylene (HDPE), and poly vinyl alcohol (EVOH) with variable morphology were comprehensively studied to give a perspective on interfacial adhesion situation. In this regard, transitions in the phase morphology of ternary systems were traced by means of scanning electron microscopic investigations, varying the type of matrix and composition in the minority phase. Theoretical and experimental analyses of impact and tensile properties provided support for the compatibilizing action of EVOH on HDPE/PA-6 immiscible blends. Rheological and thermal studies were also performed to make a broader image on the interphase region in ternary systems with core-shell and individually-dispersed minor domains. The most interesting finding was that there is a tendency for PA-6 to partially encapsulate HDPE domains within the EVOH continuous phase. This is roughly supported by SEM micrographs, but yield stress measurements placed too much emphasis on the morphological status.