Synergistic flame-retardant IFR/PP composites based on cerium phenylphosphonate

The intumescent flame retardant (IFR) composed of piperazine pyrophosphate (PAPP) and melamine cyanurate (MCA) can improve the fire safety of polypropylene (PP). However, the addition of up to 28 wt% PAPP-MCA (mass ratio of 3∶1) greatly reduced the strength and toughness of PP (by 31% and 62%, respectively). This article uses a rare earth compound CeHPP with a two-dimensional layered structure as a flame retardant synergist to enhance the fire safety of PP with relatively low PAPP-MCA content. The results showed that in the presence of 2 wt% CeHPP, adding only 20 wt% PAPP-MCA can achieve a 30% LOI of PP and pass the UL-94 V-0 grade. At the same time, the PHRR, THR, and TSR of PP composite materials are significantly reduced by 82%, 85%, and 52%, respectively. In addition, compared with PP composites with the addition of 28wt% IFR at the same V-0 level, the tensile strength and elongation at break of CeHPP-IFR synergistic flame retardant PP composites increased by 22% and 110%, respectively, demonstrating more ideal mechanical application potential.