Synthesis and thermal behaviour of polyamide 6/bentonite/ammonium polyphosphate composites

In order to achieve acceptable levels of flame retardancy of polymers, phosphorus-based flame retardant (FR) additives at about 20-30% w/w are required which is too high for conventional synthetic fibres. To know whether more finely sized particles of conventional FRs with or without nanoclay are more effective at the same concentration, composites of PA6 with bentonite and ammonium polyphosphate (APP) have been prepared by melt processing in a twin-screw extruder. XRD peaks and TEM images of PA6/Org-bentonite composite show partially ordered intercalation and ordered exfoliation. Thermal analysis in He shows that thermal stability of PA6 nanocomposite has increased by 18 degrees C compared with pure PA6 during degradation after 425 degrees C but it has decreased by 100 degrees C on inclusion of APP in PA6/nanoclay composites. The char yield is increased by 20% in PA6/bentonite/APP composites. No effect on thermal stability or char yield is observed by reducing the particle size of APP. (c) 2008 Elsevier Ltd. All rights reserved.