Influence of polyamide ratio on the CNT dispersion in polyamide 66/6 blends by dilution of PA66 or PA6-MWCNT masterbatches

Abstract

Nanocomposites with 3wt.% multi-walled carbon nanotubes (MWCNTs) are produced by melt dilution technique using two commercial masterbatches where MWCNTs are pre-dispersed in PA66 and PA6. As polymer matrix, two blends (polyamide 66 (PA66)/polyamide 6 (PA6)) are assessed with different PA66/PA6 ratio (25/75 and 50/50). The influence of both masterbatch and polyamide ratio on microstructure of CNT composites and the relations between microstructure and physical properties (dielectrical properties, crystallinity and rheology) are analysed.Though all nanocomposites are rheologically percolated, those prepared from PA6 masterbatch show higher stiffness. The highest conductivity value corresponds to the nanocomposites with 50/50 PA66/PA6 ratio, possibly because the nanotubes form well-distributed big agglomerates in co-continuous blend morphology. Comparing the different masterbatches, the best electrical results are obtained with PA6 masterbatch, probably due to the fact that its lower melt-viscosity encourages CNT dispersion during extrusion and subsequent re-agglomeration during compression moulding.