writer：Zhang Y, Li XN, Cao ZH, Fang ZP*, Hull TR*, Stec A
keywords：Zinc chelate; Low density polyethylene; Fire retardant; Mannich condensation; Flammability
source：期刊
specific source：Ind. Eng. Chem. Res., 2015.4, 54(13): 3247-3256
Issue time：2015年
A novel oligomeric intumescent fire retardant chelate, zinc phosphonated poly(ethylene imine) (Zn-PEIP), with a changeable Zn2+ loading, was synthesized. The chemical structure of Zn-PEIP was confirmed by FTIR, 13C NMR and 31P NMR spectra. The thermal behavior and fire retardancy of low density polyethylene (LDPE) containing 25 wt% Zn-PEIPs with different amounts of Zn2+ were investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI) and cone calorimetry. The TGA results showed that higher concentrations of Zn2+ improved the thermal stability and increased the residue yield of LDPE. However, the data from the LOI and cone calorimetry showed that there is an optimum concentration of Zn2+ for the best fire retardant performance of LDPE. This is ascribed to the high crosslink density resulting from zinc bridges, preventing normal swelling of the intumescent system. The surface morphology of the char was characterized by digital photographs and scanning electron microscopy (SEM). This confirmed the optimum intumescence, coherent and strong barrier layer formation at an intermediate Zn2+ loading.