Abstract. Binders exert a strong influence on the safety and explosion properties of polymerbonded explosives (PBX) based on pentaerythritol tetranitrate (PETN). In this paper, the thermal behavior and decomposition kinetics of two PBX samples formulated from PETN were evaluated along with a PETN sample using various thermal techniques and analytical methods. The experimental results demonstrate that the nitrocellulose (NC) binder accelerated the thermal decomposition process and hence reduced the thermal stability and shelf-life of the PBX compared to PETN, whereas the polystyrene (PS) binder seems to play no negative influence on the thermal stability of PETN in the PBX composition.
In this paper, the structural characteristics of the modified celluloses from acacia pulp in Vietnam were investigated and compared to other pulps. The total crystalline index (TCI), the lateral order index (LOI) and the hydrogen bond intensity (HBI) were evaluated by the FTIR spectra. The size of crystallites was considered by XRD patterns. Peak separations were carried out using Gaussian deconvolution for the band at 3700 -3000 cm -1 of the FTIR spectra and the XRD spectra. The results show that the TCI, LOI and HBI of modified acacia cellulose I are found to be around 1.09, 2.22 and 2.33, respectively, and the TCI, LOI, HBI of acacia cellulose II are found to be around 1.09, 1.51, 2.06, respectively. The crystalline size of modified acacia cellulose I is found to be as follows L(101) ~ 4.33 nm, L(101 ) ~ 8.58 nm and L(002) ~ 4.80 nm, and that of cellulose II is found to be as follows: L(101) ~ 4.04 nm, L (101 ) ~ 3.55 nm and L(002) ~ 2.99 nm.
The article presents results of effect of factors comprising the types of irradiation, the concentration of NR solution and the content of hydroperoxide in mixture on photochemical depolymerization of natural rubber. The results showed that the ultraviolet irradiation from the vapor mercury lamps (HSW-250W and HSW-125W) caused the faster rate of depolymerization than the light from HF-500W; increasing concentration of NR in toluene leaded to decrease the rate of depolymerization; and as the content of hydroperoxide increased the rate of depolymerization was faster. Additionally, the IR spectra, 13C-NMR of products were determined and showed that the cis-1,4-isoprene structure has not been changed and there was the presence of hydroxyl-terminated groups and a few epoxy groups in chains.
The kinetic parameters of thermal decomposition reactions are important in predicting the potential of energetic material systems for the thermal explosion. In this study, the thermal decomposition behaviors of three polymer‐bonded explosive samples based on hexogen and nitrocellulose were evaluated and compared to the hexogen sample. The results show that the binder based on nitrocellulose has negatively affected on the thermal stability of polymer‐bonded explosives. The activation energy of the polymer‐bonded explosive was reduced by approximate 25 % compared to that of hexogen. Moreover, while hexogen exhibited an estimated shelf‐life of 70 years, the polymer‐bonded explosives could remain their safety and explosion properties for only around 45 years. Finally, increasing the nitrocellulose content from 3.75 to 6.67 wt.% reduced the thermal stability and shelf‐life of the polymer‐bonded explosive.
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