Synergistic effect of phosphorus‐containing nanosponges on intumescent flame‐retardant polypropylene

Abstract

Abstract A novel nanosponge (NS) was synthesized via the crosslinking of β‐cyclodextrin with epoxy resin. Subsequently, a phosphorus‐containing nanosponge (P–NS) was prepared by the absorbance of resorcinol bis(diphenyl phosphate) into the NS, and it was used as a synergistic agent of intumescent flame retardance in a polypropylene (PP)/melamine pyrophosphate/pentaerythritol composite. The synergistic effect between P–NS and the intumescent flame retardant (IFR) was investigated by thermogravimetry, limiting oxygen index (LOI) testing, vertical burning (UL‐94) testing, cone calorimeter testing, and scanning electron microscopy (SEM). The results show that P–NS significantly improved the flame retardancy of the PP/IFR composite. When 3.0 wt % P–NS replaced the same amount of IFR in the composite, the LOI value increased from 29.0 to 32.5%, the UL‐94 rating was enhanced from V‐1 to V‐0, and the peak heat release rate decreased substantially from 343 to 235 kW/m 2 . Simultaneously, the total heat release and mass loss rate decreased dramatically. Furthermore, the SEM results show that the quality of char formation of the PP/IFR/P–NS was superior to that of the PP/IFR composite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012