Organic modification of Mo-decorated MgAl layered double hydroxide for polymer flame retardancy

Abstract

A novel stearic-pillared MgAl layered double hydroxide (S-Mo/LDH) containing MoOx nanoparticles was successfully prepared by calcination-reconstruction, where MoOx nanoparticles were decorated onto the surface of the S-Mo/LDH by reducing the MoO42−-pillared LDH precursor (Mo-LDH). The microstructures, bonding states and surface properties were investigated by XRD, SEM, FT-IR, BET/BJH, WAC and TG-DTG, which confirmed that the interlayer MoO42− anion was grafted onto the brucite sheets to form MoOx nanoparticles during the calcination process of the Mo-LDH, and stearic anions were intercalated into the interlayers of the S-Mo/LDH. The performances of the flame-retardancy were improved by combining these properties of the individual materials of stearic, parent LDH and MoOx nanoparticles. In comparison to the Mo-LDH, the S-Mo/LDH demonstrated a more homogeneous dispersion in polypropylene (PP) matrix due to surface hydrophobicity. The incorporation of the S-Mo/LDH filter at 20 g∙100 g−1 loading provided an excellent fire resistance towards PP matrix, giving the high limited oxygen index (28.6%), vertical burning UL94 (V-0) and reduced total heat release (71.6% reduction in PHRR relative to neat PP). These remarkable properties indicated that the approach to improve flame retardancy of PP was a cost-effective, feasible and highly effective way.