Different inhibition mechanisms and safety effects of TPU and EVA on thermal decomposition of RDX

The combination of energetic materials (EMs) and binders into polymer-bonded explosives (PBX) is an important method for modifying explosives. To explore the effect of thermoplastic polyurethane (TPU) and ethylene-vinyl acetate copolymer (EVA) on pyrolysis and safety performance on EMs, the RDX-based PBXs were prepared by mechanical mixing method, direct method and microencapsulation method, respectively. Scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were used to find out composites for the possibility of further application. The PBXs samples coated by TPU or EVA using the direct method with the maximal enthalpy of mixing were selected and characterized by X-ray powder diffraction (XRD) and transform infrared spectroscopy (FTIR). The thermal decomposition tests of RDX and the two prepared PBXs were further carried out by thermogravimetry/infrared/mass (TG/IR/MS). The impact sensitivity and laser ignition tests were also performed to determine the mechanical sensitivity effect and ignition influence of the two binders on RDX. The result indicated that TPU increased the activation energy of RDX and inhibited the subsequent pyrolysis process. EVA significantly increased the decomposition peak temperature, indicating that it can improve the initial thermal stability of EMs. Both TPU and EVA improve the ignition performance, but EVA reduces the impact sensitivity. Therefore, EVA exhibits better performance than TPU in RDX-based PBXs.

Automated summary

This study investigated the effect of thermoplastic polyurethane (TPU) and ethylene-vinyl acetate copolymer (EVA) on the pyrolysis and safety performance of polymer-bonded explosives (PBX) containing energetic materials (EMs). The results showed that TPU increased the activation energy of the EMs and inhibited the pyrolysis process, while EVA improved the thermal stability and ignition performance.