The influence of poorly-/well-dispersed organo-montmorillonite on interfacial compatibility, fire retardancy and smoke suppression of polypropylene/intumescent flame retardant composite system

A novel linear polymeric charring agent (PEPAPC) was synthesized via the nucleophilic substitution reaction, and then embedded into polypropylene (PP) substrate to improve the fire retardancy and anti-dripping performance. Unfortunately, the opposite polarity between intumescent flame retardant (IFR) and polymer-matrix could seriously deteriorate the interfacial compatibility, harmful to the flame-retardant efficiency and smoke toxicity suppression of PP/IFR composites. For the foregoing reasons, flame retardant PP/IFR/Organo-montmorillonite (OMMT) nanocomposites with the combination of maleic anhydride-grafted PP as compatibilizer have been prepared via melt intercalation technique. When 2 wt% well-dispersed OMMT were incorporated, it showed a significant reduction in peak heat release rate and total heat release (90.5 and 62.7%) compared with pristine PP, and an achievement in limiting oxygen index value of 32% from 18.5% for pristine PP, which can be attributed to the nano-barrier and catalytic carbonization effect of well-dispersed OMMT within the polymer-matrix. More importantly, the well-dispersed OMMT displays significant smoke toxicity suppression, toughening and strengthening effect on PP/IFR system. The peak CO release and total smoke production for PP-6 were decreased by 89.8 and 64.7%, respectively. This work may provide an effective approach towards fabricating high-performance polymeric materials on organic/inorganic hybrid nanocomposites with homogenous dispersion, thereby effectively reducing the fire hazard risk.