Application of Functionalized Graphene Oxide in Flame-Retardant Polypropylene

A surface functionalized graphene oxide (FGO) was prepared by a simple and efficient method of treating graphene oxide (GO) with pentaerythritol (PER) in water using an ultrasound process. After the PER was grafted onto the surface of the GO, the GO became hydrophobic instead of hydrophilic and precipitated as a dark brown material. The results of Fourier-transform infrared analysis, X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscopy demonstrated that the PER had been successfully attached to the GO. Subsequently, the FGO was incorporated into the intumescent flame-retardant-polypropylene system. The presence of FGO improved the flame-retardant efficiency as evidenced by the limiting oxygen index (LOI) and vertical burning test (UL-94) test. Analysis by scanning electronic microscopy indicated that the FGO promoted the formation of a continuous, intact residual char layer on the surface of the polymer, which acts as an insulating barrier to protect the base material. As a result, it delayed the peak of heat release rate and increased the residual mass obtained on combustion of the polymer. (C) 2014 Society of Plastics Engineers