Carbon nanotube bridged cerium phenylphosphonate hybrids, fabrication and their effects on the thermal stability and flame retardancy of the HDPE/BFR composite

Multiwalled carbon nanotube (MWNT) bridged cerium phenylphosphonate (CeHPP) hybrids (Ce-MWNTs) were facilely prepared through the in situ introduction of MWNTs into the hydrothermal reaction system of CeHPP, aiming at enhancing the flame retardancy of the polymer. Morphological observations indicated that the MWNTs acted as bridges to connect CeHPP lamellas to form a consecutive structure. Moreover, due to the good dispersion of CeHPP and the acting force between CeHPP and the MWNTs, the hybrids were dispersed uniformly resisting the strong intermolecular attractions. The hybrids led to a reduction in the peak heat release rate (PHRR) of the conventional flame retardant high-density polyethylene (HDPE) composite and improved the UL-94 grade from V-2 to V-0, indicating that they could confer a better flame retardancy on HDPE compared to the CeHPP or MWNTs alone. The results of the pyrolysis products and the morphology of the chars gave the evidence that Ce-MWNTs could enhance the physical barrier effect to retard the vaporization of flammable gases and the transfer of heat because of the mutual complementarity of the CeHPP and MWNTs.