TiO₂ loaded on graphene nanosheet as reinforcer and its effect on the thermal behaviors of poly(vinyl chloride) composites

Titanium dioxide/graphene hybrids were synthesized by a facile in situ solvothermal route and introduced to enhance the properties of the poly(vinyl chloride) (PVC) materials. X-ray diffraction and transmission electron microscopy results indicated that TiO₂ nanoparticles were homogeneously anchored on the graphene oxide nanosheets and the reduction of graphene oxide occurred simultaneously during the one-pot solvothermal process. With the incorporation of 2.0wt% graphene/TiO₂ hybrids, a 3.5°C increment in the glass transition temperature and a 50% increase in the storage modulus were observed compared to neat PVC. The improvement of the temperature of maximum mass loss rate and reduction of maximum mass loss rate were also observed from thermogravimetric analysis, indicating the enhanced thermal stability of PVC composites. Moreover, the reduced peak heat release rate and HCl release rate obtained from microscale combustion calorimeter and thermogravimetric analysis-infrared spectrometry indicated the superior fire safety of PVC composites. The changes of the fire behavior were primarily attributed to the synergistic effects of graphene/TiO₂ hybrids: the adsorption and barrier effect of fillers slow down the thermal degradation of polymer, and restrain the heat transfer and the flammable or toxic gaseous products release.