Morphologies in Polyamide 6/High Density Polyethylene blends with high amounts of reactive compatibilizer

The morphologies (dispersed, stretched dispersed, fibrillar and co-continuous) obtained in twin screw extruders in reactively compatibilized PA6/HDPE/Maleic Anhydride-grafted-HDPE blends have been studied over a broad range of compositions, specifically with high amounts of compatibilizer, by Scanning Electron Microscopy (SEM) after selective phase dissolution. The conversion ratio of the compatibilization reaction is estimated to be very high (of order 80%) in co-continuous morphologies. The morphologies exhibit two characteristic sizes: subdispersions of a few tens of nm coexist with larger (micrometric) scale morphologies. Large scale morphology regions have been identified in ternary compositions diagrams. The location of the co-continuity region agree with theoretical models based on rheological properties. The observed large scale morphologies, however, are not compatible with the high fraction of copolymer formed in the system after reactive extrusion. This implies that most of the copolymers are under the form of nanometric subdispersions within large size domains.