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In this work, a hydrothermal method was used to prepare a novel, sulfur-free expandable graphite (EG), which was added to high-density polyethylene (HDPE) to improve the flammability and the dripping behavior of composites. Phosphoric acid (H3PO4) was utilized as the intercalating agent, and potassium permanganate and nitric acid were used as the oxidizing agent. EG was investigated using Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry, energy dispersive spectrometry, and scanning electron microscopy. Thermogravimetric analysis, the limiting oxygen index (LOI) and UL-94 were used to examine the thermal and flame-retardant properties of the composites. The results demonstrated that the EG composite exhibited much better thermal stability than pure polymer. Additionally, at 30 wt% EG loading, the LOI value of HDPE/ EG fabrication by H3PO4-hydrothermal method (PEG) was 30, and the flammability standard of UL-94 reached the V0 level, verifying that the EG that was prepared using the H3PO4-hydrothermal process can effectively be used in fireproof composites. The tensile modulus of the composites increased with increasing filler content, while the tensile strength decreased. EG enhanced flexural strength and flexural modulus of HDPE composites but not with high EG loading. The impact strength of the composites was diminished due to the incorporation of EG into HDPE matrix.

tert-Butyl hydroperoxide (TBHP, 70 mass %), which is a solution of liquid peroxide, has been widely employed in the chemical industry as a polymerization initiator. The smart technology for predicting the mechanism of thermal decomposition and the inhibitive or hazardous reaction of TBHP by different calorimetric tests involves using differential scanning calorimetry (DSC) nonisothermal tests versus DSC isothermal tests and vent sizing package 2 (VSP2) adiabatic tests versus DSC nonisothermal tests, respectively, for further understanding how to extinguish organic peroxide accidents under fire scenario or runaway reaction in a chemical plant. Meanwhile, TBHP mixed with inhibitive and hazardous materials, such as various protic acids to help prevent runaway reactions, was applied on fires or explosions in the fire system. The results could be available to fire-related agencies as a reference application. The fire extinguishing system must be well-designed to decrease the degree of hazard.

This work presented the ozone (O 3 )-hydrothermal process to prepare expandable graphite (EG), which is one kind of halogen-free flame retardant. The results showed the expanded volume of EG using the O 3 -hydrothermal process (O 3 -HEG), which is higher than those compared with convectional liquid phase synthesis, ultrasound irradiation, and hydrothermal method. Raman spectra and energy dispersive x-ray were used to analyze the structure and confirm that the EG had been prepared. Scanning electron microscope was utilized to observe the morphology of EG and expanded graphite. Thermogravimetric analysis shows that EG can slowdown thermal degradation of polymer and improve the thermal stability of composites. Limiting oxygen index value of composites with 40 wt% loading of O 3 -HEG is 33, which is higher than that of high-density polyethylene (HDPE)/natural graphite composite. HDPE composites-containing 30 wt % O 3 -HEG is capable of passing the V-0 classification and has an anti-dripping behavior.

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