The mechanisms for desensitization effect of synthetic polymers on BCHMX: Physical models and decomposition pathways

Sensitivity and Performance of Energetic Materials

“…Authors Yane tal. have studied the influence of variouslybased polymeric binders on the cyclic nitramines RDX, HMX, BCHMX and e-HNIW: polyisobutylene (C4 matrix), acrylonitrile-butadiene rubber (Semtex 10 matrix), styrene- butadiene rubber (Formex matrix), vinylidene fluoride, and hexafluoropropene copolymer (Viton A200)a nd the terpolymer of vinylidenef luoride,h exafluoropropylene, and tetrafluoroethylene (Fluorel), and the results are presented in an interestings eries of papers [157][158][159][160][161][162][163].I tw as found that the Formexb inder has as ignificant effect on the activation energy distribution of nitramines [163], thath ydrocarbon polymers have little effect on the thermals tability of BCHMX [157],a nd in the caseo fH NIW,t hat the binders C4, Semtex and Formex could greatly mitigate the decomposition process of this nitramine from as ingle step to am ultistep, resulting in lower impact sensitivity,w hereas fluoropolymers have only as lighte ffect [158].I th as also been proved that Semtex and Viton Aa re better binders than C4 and Formexf or HNIW and RDX based PBXsi n terms of their greater thermals tability,a nd Formex is ap oor binder for BCHMX [160].Avacuum stability test with these PBXs has shown [ 32,33] that the C4 matrix does not fully eliminate the specific influence of the nitramine filler's molecular structure (crowdingi nt heir molecules-in HNIW and BCHMX) on the initiationr eactivity of the corresponding PBXs.T his represents ad ifference from the study of PBXs with the Formex P1 binder [33] where their matrices increase the reactivity of the nitramine fillers to such an extent that the above mentioned specific influence of molecular structure is practically eliminated.…”

“…[154,155]) can be obtainedw ithouts erious difficulty using the TGA and DSC techniques. Theset echniques have been usedf or thermal reactivity specificationo fq uite an umber of PBXs [157][158][159][160][161][162][163] on the basiso fw hich the sensitivity of the given PBX [158] and cook-off time [159] were predicted and interpreted. Al inear relationship between the activatione nergies of this thermolysis and the sumo f the negative and positive extremes of molecular surface electrostatic potentials, V S,S ,o ft he nitramines studiedh as been successfully used for analysis of the kinetic data obtained from thermolysis of nitramines [147];t hese summed potentials also correlate well with the rate constants for the monomolecular thermald ecomposition of the nitramines mentioned [147].Astatistical method of predicting the activation energies of the thermolysis of some 86 polynitro compounds [148] was the precursor of the new program, named EDPHT2 .0, which is usable also for predictiono f the crystald ensity and enthalpyo ff ormation [149].V ery important critical temperatures can be obtained from the kinetic data of thermoanalytical measurements with EMs [50,79,141,154,155,159,[164][165][166][167][168][169].T he important small and larger cook-off tests [50,[173][174][175][176][177][178][179][180][181]…”

Thermal behavior of 1,3,5-trinitroso-1,3,5-triazinane and its melt-castable mixtures with cyclic nitramines

“…The E a of pure RDX decreases with the extent of reaction [25], while that of RDX-TMTA following similar trend but has much higher initial activation energy (over 300 kJ mol −1 when ␣ < 0.1). The decomposition activation energy of pure BCHMX is about 240 kJ mol −1 for the first step and 186 kJ mol −1 for the second one [26]. Under the effect of TMTA, the decomposition of BCHMX may occur in one step (the second decomposition step of BCHMX-TMTA) with slightly higher activation energy than that of the second step of pure BCHMX, whereas the second decomposition step of this mixture can be considered under the influence of aminic products from TMTA decomposition.…”

“…It means the inclusion of TMTA does not change the mechanism of the rate-limiting decomposition process of BCHMX. However, the first step decomposition of BCHMX was restrained by TMTA, which is very similar to C4 and Formex binders that can change BCHMX decomposes from two steps to a single complex step [26].…”

Mechanism of Two Typical Binders BR and F2604 on Thermal Decomposition of HMX

“…The thermal decomposition behavior and kinetics of HMX-based PBX have been extensively studied through non-isothermal thermogravimetry (TGA) or differential scanning calorimetry (DSC). − In the published literature, more attention has been paid on the thermal decomposition behavior and kinetics of PBX based on HMX mixed with a binder, yet fewer articles focus on different reaction mechanisms caused by the basic reaction between binder and HMX. Wu et al studied the thermal decomposition behavior of CL-20/HMX eutectic with nano-Fe 2 O 3 and rGO-Fe 2 O 3 by DSC–TG–MS–FTIR coupling technology and proposed the thermal decomposition mechanism of CL-20/HMX eutectic.…”