Flame retardant polyamide 6 nanocomposites and nanofibers : processing and characterization
Polyamide 6 (PA6) was melt-blended with an intumescent flame retardant (FR) and nanoparticles (multi-wall carbon nanotubes [MWNTs] and nanoclays) to produce multi-component FR-PA6 nanocomposites. Thermal, flammability properties, char residue morphology, and mechanical properties of FR-PA6 nanocomposites were characterized. The flame retardant properties were enhanced according to UL 94 and microscale combustion calorimeter (MCC) measurements, whereas the thermal stability was decreased. Mechanical properties of the bulk material, especially elongation at break, were severely reduced, with the exception of tensile modulus which increased significantly. FR-PA6 nanofibers were processed via electrospinning. Electrospinnability, morphology of the nanofibers, combustion, and thermal properties were also analyzed. As for the bulk-form nanocomposite, improved combustion properties of these nanofibers were successfully achieved though thermal stability was compromised. With proper FR additive, the synergism between MWNTs and nanoclays was observed in PA6 resin.