Preparation of expandable graphite via ozone-hydrothermal process and flame-retardant properties of high-density polyethylene composites

Abstract

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.

Highly energetic compositions based on functionalized carbon nanomaterials

“…There are several popular ways to prepare E b G as an excellent halogen-free flame retardant, including liquid phase synthesis, ultrasonic irradiation, and hydrothermal methods. 82,83 Recently, a new preparation procedure was developed, where natural graphite was initially dispersed in H 2 O 2 and then introduced into an autoclave to proceed with a hydrothermal process. 84 In all the cases, under the influence of heat, the graphite layers are separated as in an accordion, expanding the graphite flakes (Fig.…”

Mechanical Sensitivity Reduction of Energetic Materials by Using Carbon Nanomaterials

“…[46] Since EG possesses remarkable 3D structures such as holes, gaps and grooves, researchers believe that it has the potential to be a desensitization carrier for EMs. [5] Recently, RDX/EG intercalation composites were prepared by recrystallizing RDX crystal into the EG using solvent/anti-solvent method (figure 2) [7] . This composite is actually a half-coated parallel multi-sandwich like microstructure, the embed ration of RDX into EG could reach 80.0 wt.% ~87.0 wt.% when the concentration of RDX solution is over 1.1 mol/L and the volume ratio of solvent to anti-solvent was 1:6.…”