Processing - morphology - property relationships of polyamide 6/polyethylene blend-clay nanocomposites

In this work, we studied the effect of the method of preparation and of reprocessing on the morphology and, consequently, on the physical properties of polyamide 6 (PA6)/high density polyethylene (HDPE)-clay nanocomposite blends in the presence of different compatibilizers. In particular, the nanocomposites were obtained by melt mixing using a co-rotating twin screw extruder (E1). The blends thus obtained were re-extruded (E2) under the same operating conditions. Moreover, blends with the same final composition were produced using a masterbatch of the compatibilizer with the clay prepared in a separated stage in a batch mixer (MB). All the materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffractometry (XRD) analyses. In addition, the rheological behaviour and the, tensile and impact, properties were evaluated. The XRD and TEM analysis showed that re-extrusion slightly improves the morphology of the nanocomposites. A further improvement of the morphology, in terms of lower clay dimension and better dispersion, was observed in the MB blends. The results of the mechanical tests showed that reprocessing (E2) induced an increase of all the properties for all the three systems. A further general increase of the mechanical properties was showed by the MB blends.