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. J. VINYL ADDIT. TECHNOL., 21:278-284,
A novel charring agent, poly(p-ethylene terephthalamide) (PETA), for halogen-free flame retardant polypropylene was synthesized by using p-phthaloyl chloride (TPC) and ethylenediamine through solution polycondensation at low temperature, and the effects of PETA on flame retardance of polypropylene (PP)/IFR systems were studied. The experimental results showed that PETA could considerably enhance the fire retardant performance as proved by evidence of the increase of limiting oxygen index (LOI) values, the results of UL-94 tests, and cone calorimeter tests (CCT). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) demonstrated that an appropriate amount of PETA could react with PP/IFR system to form cross-link network; a more compact char layer could be formed which was responsible for the improved thermal and flame retardant properties of PP/IFR systems. However, the superfluous amount of PETA would play the negative role.
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