Interfacial interaction of clay with binary blends of polyamide 6 with High-Density Polyethylene (HDPE) and HDPE-graft-acrylic acid studied by Positron Annihilation Lifetime Spectroscopy

Positron Annihilation Lifetime Spectroscopy (PALS) has been utilised to investigate the free-volume properties of polyamide 6 (PA-6)/HDPE, PA-6/HDPE-graft-acrylic acid (PEAA) and their nanocomposites with organo-clay (Oclay). There is a great difference in the average size of free-volume holes (R) and the fractional free-volume (fv) of PA-6 and HDPE owing to their different polarity. And the variations of R and fv as functions of Oclay content are different between two blends. In PA-6/HDPE system, when added 1.2 per hundred resin (phr) and 2.4 phr Oclay, R and fv increased slightly, while in PA-6/PEAA system, R and fv decreased. The complicated relationship between the free-volume and the Oclay content is due to the interaction effect of Oclay on blends' interface.