Effect of trace chloride on the char formation and flame retardancy of the LLDPE filled with NiAl‐layered double hydroxides

Abstract

SummaryLayered double hydroxides (LDHs) have received intensive attentions for the potential as flame retardants of polyolefin. In the work, trace amounts of chloride were investigated for their synergistic effects on the char formation and flame retardancy of the linear low‐density polyethylene (LLDPE) filled with NiAl‐LDHs. Results showed that 0.5 wt% of NH4Cl incorporation enabled the char yield of 20%LDH/LLDPE (20 wt% of NiAl‐LDH) increase from 10.4% to 49.6%. Other chlorides likewise offered significant increase in the char yield of 20%LDH/LLDPE. With the flame‐retardant measurements of cone calorimeter and limiting oxygen index device, it is revealed that the flame retardancy of LLDPE filled with NiAl‐LDHs could be greatly improved when trace amounts of NH4Cl were further introduced. Thermal stability analysis illustrated that the presence of NiAl‐LDHs or NH4Cl all had positive effects on the thermal stability of LLDPE, in which the chlorides influenced the LLDPE thermal stability via direct participation in the degradation of LLDPE. The synergetic mechanism analysis reveals that the introduction of chloride enabled the LLDPE decomposed products have more tendency to grow carbon nanotubes with the presence of NiAl‐LDH catalysts. Finally, the mechanical properties of LLDPE filled with NiAl‐LDHs and NH4Cl were also investigated.