Improving the Thermal Stability and Flame Retardancy of PP/IFR Composites by NiAl-Layered Double Hydroxide

Nickel and aluminum layered double hydroxide (NiAl-LDH) was synthesized via co-precipitation and modified by sodium dodecyl sulfate (SDS), which was marked as NiAl-OLDH. The structure of NiAl-LDH was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). In order to investigate the role of LDH on polymer/intumescent flame retardant (IFR) systems, polypropylene (PP)/IFR/NiAl-OLDH nanocomposites were prepared by melt intercalation. Thermal and flame retardant properties of PP/IFR/NiAl-OLDH nanocomposites were studied. The results indicated that incorporation of NiAl-OLDH in PP/IFR composites significantly improved the thermal stability, flame retardancy and smoke suppression properties. With the addition of 5 wt% NiAl-OLDH, PP/IFR/NiAl-OLDH nanocomposites obtained UL-94 V0 level and the LOI value reached 27.5%. Compared with those of PP/IFR, the peak heat release rate (PHRR), total heat release (THR) and peak smoke production rate (PSPR) values reduced 49%, 10%, and 63%, respectively, which were attributed to the barrier effect and excellent charring performance of NiAl-OLDH.