Synergistic effects of pentaerythritol with aluminum hypophosphite in flame retardant ethylene‐vinyl acetate composites

The synergistic effects of pentaerythritol (PER) with aluminum hypophosphite (AHP) in halogen‐free flame retardant EVA/AHP/PER composites have been studied by cone calorimeter test (CCT), limiting oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The data obtained from CCT show that the suitable amount of PER could considerably decrease the HRR and SPR values and prolong the combustion time of the EVA/AHP/PER composites. The results from LOI and UL‐94 show that a suitable amount of PER played synergistic effects on EVA/AHP/PER composites which increased the LOI value. The TGA data reveal that PER increased the char residues of the EVA/AHP/PER composites which made the EVA/AHP/PER composites have better thermal stability. SEM measurement results give positive evidence that the compact charred layers formed when 8 wt% AHP is substituted with PER and rich compact char layers could explain the excellent flame retardance. The mechanical properties results indicate that when AHP is substituted with a suitable amount PER, the tensile strength and elongation at break of EVA/AHP/PER composites can be maintained. POLYM. COMPOS., 39:2299–2306, 2018. © 2016 Society of Plastics Engineers