Rheological behaviors of nylon 6/silica modified melamine cyanurate non-halogen flame retardant composites

Nylon 6 (PA 6)/silica modified melamine cyanurate (MCA) flame retardant (FR) composites were prepared by melt blending method. The morphology and rheological behaviors of composites were characterized using scanning electron microscopy and capillary rheometer. The results show that the presence of silica can improve the dispersion of mMCA in PA 6. The rheological behaviors are significantly affected by temperature, shear rate and the structure of composites. With increase of temperature and shear rate the apparent viscosities of composites decrease. All composites are pesudoplastic fluids. At same temperature and shear rate PA 6 composites, which contain different flame retardants (FRs) and different loadings, exhibit different viscosities. The presence of MCA can enhance the non-Newtonian index of composites. The flow activation energies (E) of PA 6/silica modified MCA (S-mMCA) composites are larger than that of PA 6/pure MCA composites, and, with the increasing shear rate the flow activation energies of composites decrease. At a fixed FRs content, with the increase of silica loading, E of PA 6/S-mMCA composites increases firstly and then decreases. These results would be useful for the processing of FR PA 6 composites and for further understanding their flame retardant mechanisms.