摘要:

AbstractThermogravimetric analysis (TGA) at constant temperature was used to measure weight loss of plasticized nitrocellulose (NC) propellants due to vaporization of plasticizer. Plasticizers consisted of three 2‐nitroxyethylnitramine (NENA) compounds, diethylene glycol dinitrate (DEGDN), and nitroglycerin (NG). Initial concentration of plasticizer and degree of nitration of NC were also varied. Each propellant was tested at three temperatures. Plasticizer diffusivities (D) and their activation energies were calculated. Observed trends were generally consistent with calculated plasticizer solubility parameters, expected increases in molecular mobility for more highly plasticized materials, and the more polar and more disordered structure of NC with a lower degree of nitration. Some unexpected effects could be explained by changes in entropy of activation due to variation in plasticizer or NC structure. In general, the NENA plasticizers had lower vaporization rates than DEGDN or NG, suggesting that plasticizer losses during manufacturing or storage of practical formulations should not be a proble

ISSN:0721-3115    

DOI:10.1002/prep.19950200202

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractA new model is presented to predict the cumulative breakup time of the jet from a shaped charge liner. The model invokes a plastic instability criterion, kinematic considerations, and a material constitutive equation. Very good agreement of the cumulative breakup time and jet length with experimental data for several copper liner geometries is shown. The results are dependent on the initial strain rate and jet temperature distribution.

ISSN:0721-3115    

DOI:10.1002/prep.19950200203

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractPolyvinyl nitrate (PVN) is one of the few known polymeric explosives. PVN was prepared by controlled addition of cooled nitric acid to a pre‐cooled suspension of polyvinyl alcohol in acetic anhydride and subsequent processing of the reaction product. Nitrogen content of different PVN samples was in the range 11.76% to 15.71%;, and the molecular weight about 100000. Several properties of PVN have been investigated and correlated with its degree of nitration. Scanning electron micrographs of PVN fibres show a porous surface. Abel heat test values at 82°C indicate that fibrous PVN has a fairly good degree of stability, which decreases with increase in its % N. Addition of small amounts (0.25%; by wt.) of DPA, 2NDPA, carbamite and resorcinol into PVN (15.71%; N)improves its heat stability. With increasing %;N, ignition temperature of PVN decreases and impact as tetryl. With increasing %; N from 11.76%; to 15.71%;, heat of combustion decreases from 3744 cal/g to 3023 cal/g, and heat of explosion increases from 456 cal/g to 987 cal/g, due to increase in oxygen balan

ISSN:0721-3115    

DOI:10.1002/prep.19950200204

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractGaps 0.8‐mm wide and transverse to the direction of detonation in high‐performance high explosive compositions, such as squeeze cast TNT/HMX (15/85) or pressed HMX/B (97/3), show no measurable time delay, or it must be less than 50 ns. As expected, delay times increase with the gap width. A surprising result, however, is the convex shape of the time delay curves, which begins at a gap width of about 1 mm. The delay time curves from air and plexiglass‐filled gaps resemble one another very

ISSN:0721-3115    

DOI:10.1002/prep.19950200205

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThermal decomposition of pure HMX shows DSC endothermic peaks at 210°C from β to γ phase transformation and at 285°C from the HMX melting followed by an instantaneous exothermic decomposition leading to a strong peak at 290°C and a very strong DTG peak at 325°C with a mass loss of 95%. However, the GS‐2 mixture shows two DSC exothermic peaks at 225°C and 270°C assigned to nitroguanidine etc. and HMX decomposition. Addition of NH4ClO4to HMX causes the decomposition to take place before melting and decomposition peak is lowered to 230°C. However in the case of GS‐2, a strong effect was observed and the amount of the mixture was to be decreased to obtain a reasonable DSC curve. This shows that the addition of NH4CIO4to HMX increases the decomposition of HMX, however this effect is more pronounced in GS‐2 mixture. Even the minimum concentration of NH4CIO4tested (10%) shows strong effect.The addition of NH4NO3to HMX and GS‐2 shows DSC exothermic decomposition peaks at 272°C and 245°C, showing a contribution from NH4NO3decomposes near to the decomposition of HMX, it does not show a strong effect on the decomposition of HMX/GS‐2 as compared to NH4ClO4. Addition of KClO4, NaClO4and KNO3don't show any effect in these ther

ISSN:0721-3115    

DOI:10.1002/prep.19950200206

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThermal decomposition and the burning properties of fluorocarbon/boron/AP propellant granule have been investigated. The fluoro‐carbon binder (FBDR) was oxidized by the decomposition products of admixed ammonium perchlorate (AP) and its decomposition region was 150°C lowered in the slow thermolysis. The boron particles, however reacted with neither FBDR nor AP at 550°C. In the micro‐motor tests, the boron particles completely burnt at a pressure range of from 30 MPa to 80 MPa in a short period of time (one millisecond) even at a low characteristic exhaust velocity. Minimum free volume, however, was needed to complete the combustion reaction in the chamber case. The characteristic exhaust velocity significantly decreased at below the characteristic chamber length of 11 cm. The boronized propellant showed low temperature sensitivity between −30°C

ISSN:0721-3115    

DOI:10.1002/prep.19950200207

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe nitrolysis of hexamethylenetetramine (hexamine, HA) and 1,3,5‐trioxane was studied by NMR spectrometry. It was found that the structure of the nitrolysis products of the trioxane could be monomethylenedinitrate, dioxymethylenenitronitrate and trioxymethylenenitronitrate, O2N(OCH2)nONO2(n = 1,2,3). Comparison of the1H and13C spectra of the nitrolysis mixture of HA with the nitrolysis products of trioxane proved that in the nitrolysis mixture of HA the methylene group which cannot be used to form 1,3,5‐triazacyclohexane (hexogen, RDX)appears incompound (2)and not incompound

ISSN:0721-3115    

DOI:10.1002/prep.19950200208

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractIn order to clarify the effect of surface properties on the burning characteristics of a delay powder, the burning rates of the red lead‐ferrosilicon‐antimony(III) sulfide delay compositions have been measured when the ingredient was pulverized using a vibro‐mill. It was found that the burning rates increased with the mixing time when the ferrosilicon ingredient alone was pulverized before preparation of the delay powder. On the other hand, the burning rate decreased if the red lead or the antimony(III) sulfide were pulverized. The reason for this is ascribed to the chemical reaction in the combustion

ISSN:0721-3115    

DOI:10.1002/prep.19950200209

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractNon‐isothermal TG curves for four samples of polyvinyl nitrate (PVN), having 15.71%, 14.95%, 13.34% and 11.76% nitrogen contents, were obtained at 5°C/min heating rate. The weight loss of PVN samples depends directly on their % N and occurs in three or more temperature zones. For PVN with 15.71% N (max 15.73% N in theory), the main decomposition step results in more rapid and complete weight loss than for PVN with lower % N, probably due to higher oxygen balance of the former. The TG data were subjected to kinetic analysis using a computer programme. For each decomposition step, the kinetic parameters (E and A) and the regression coefficient (r) were calculated on the basis of several kinetic models and equations consistent with the Arrhenius relationship. It was concluded that the thermal decomposition kinetics of all four PVN sample are best expressed by the Random nucleation model (Mampel unimolecular law) first‐order reaction. For the initial and slowest decomposition step, E ranged between 188 kJ/mol − 217 kJ/mol and In A between 46.88 s−1‐ 60.13 s−1. The In A versus E plots for all PVN samples exhibited a linear relationship, probably due to the kinetic compens

ISSN:0721-3115    

DOI:10.1002/prep.19950200210

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY

摘要:

AbstractThe energy transfer mechanism from the electric spark to the reactive solid sample in powder form has been determined. Only a small portion of the solid is heated to the explosion critical temperature through a resistive heating by electric current. In fact, hot spots develop at the thinnest part of the solid, i.e. at intergrain contact points.We studied the evolution of thermal diffusivity and of sensitivity to electric spark as a function of powdered HMX granulometry. It allowed us to specify the respective importance of the grain size and shape in this evolution.

ISSN:0721-3115    

DOI:10.1002/prep.19950200211

出版商:WILEY‐VCH Verlag GmbH    

年代:1995

数据来源: WILEY