Synthesis of graphene oxide/layered double hydroxides hybrids via co-precipitation and their polypropylene composites

Abstract

A series of hybrid particles consisting of graphene oxide and magnesium–aluminium-layered double hydroxides (GO/Mg–Al-LDHs) were prepared by the co-precipitation method and then modified by allyltrimethoxysilane (ATMS). X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, Raman spectra and field emission scanning electron microscope (FESEM) micrograph results showed the modified GO/Mg–Al-LDHs were synthesised with a smaller particle size and better dispersion. The polypropylene (PP) composites were prepared via the reactive extrusion method, and the effects of GO content in hybrids on the mechanical properties, processability, thermal stability, flame retardation, melting and crystallisation behaviour of composites were investigated in detail. The comprehensive properties of composites containing GO/Mg–Al-LDHs were excellent compared to those of Mg–Al-LDHs under the same filler concentration. Compared with pure PP, 20 wt-% of GO/Mg–Al-LDHs-2.5 increased the limiting oxygen index (LOI) value of composites from 16.4% to 28.8% with a V-0 level of U-94 testing and decreased the heat release rate (HRR) and total heat release (THR) values from 1206.4 kW/m2 and 133.9 MJ/m2 to 146.9 kW/m2 and 69.6 MJ/m2. Meanwhile, the tensile, impact strength and elongation at break were 36.2 MPa, 3.0 kJ/m2 and 68.6%, respectively. This work provided an effective strategy for enhancing the dispersion and comprehensive properties of GO/LDHs-based composites.