Interdigitated crystalline MMT-MCA in polyamide 6

Polyamide 6 (PA6) was flame retarded by using interdigitated crystalline montmorillonite-melamine cyanurate (MMT-MCA). Its morphologies were assessed by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), thermal stability by thermo-gravimetric analysis (TGA), fire retardancy by limiting oxygen index (LOI), vertical burning testing (UL-94), and cone calorimeter (CONE) tests and mechanical properties by stress strain tests. The results indicated that the interdigitated crystalline MMT-MCA was homogeneously nano-dispersed as MMT and MCA in PA6 due to a π-π stacking exfoliation mechanism. Compared with PA6/MCA and PA6/OMMT/MCA, PA6/MMT-MCA shows enhanced thermal stability and fire retardancy. With 8 wt% total loading of MMT-MCA, the sample of PA6/MMT-MCA reached UL-94 V-0 rating (3.2 mm). The MMT-MCA can also enhance the mechanical properties of PA6. A novel interdigitated crystalline MMT-MCA shows outstanding fire retardancy owing to homogeneous dispersion of MMT and MCA in PA6.