The application of infrared microimaging for the determination of the distribution,penetration depth,and diffusion profile of methyl centralite and dibutyl phthalate deterrents in nitrocellulose monoperforated propellant

Infrared microspectroscopy was used to determine quantitatively and qualitatively methyl centralite (MC) and dibutyl phthalate (DBP) diffusion profiles in cross sections of nitro-cellulose-based monoperforated propellant grains. The absorbance values of the C?O peak of DBP at 1717 cm ^?1 and the aromatic C? C peak of MC at 1496 cm ^?1 were measured relative to the NO₂ overtone peak of the nitrocellulose at 2555 cm^?1 at 10 μm intervals from the outside edge inward (external profile) and the perforation edge inward (internal profile). Infrared microimaging was used to determine the distribution and penetration depth of the DBP and MC using the C?O peak of DBP at 1717 cm^?1 and the aromatic C? C peak of MC at 1496 cm^?1 as diagnostic of the two deterrents to obtain the contour and axonometric displays of the distribution. © 1993 John Wiley & Sons, Inc.     

Phase transitions and mechanical properties of nitrocellulose plasticized by glycidyl azide polymer and nitroglycerine

Films of nitrocellulose (NC), glycidyl azide polymer (GAP), and nitroglycerine (NG) have been evaluated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, dynamic mechanical analysis (DMA), and tensile testing. The SEM micrographs demonstrate that, even at low GAP concentration, a portion of GAP will coalesce into spherical domains due to a saturation effect. This is related to the inability of higher molecular weight GAP to effectively situate itself between NC polymer chains. The addition of a small fraction of lower molecular weight NG completely changes this behavior. DMA confirms that two transitions are present and can be attributed to a plasticizer rich phase (β), a polymer rich phase (α) and that NC plasticized with GAP is in accordance with the Gordon-Taylor equation. Tensile results show that the addition of a small fraction of NG to a NC/GAP based-formulation increases elongation at break to values similar to that of the NC/NG base formulation. The combination of these two plasticizers, GAP and NG, allows for the plasticization of NC at significantly lower environmental and human toxicity levels.     

Diffusion of deterrents into a nitrocellulose matrix. An example of diffusion with interaction

The diffusion of various concentrations of a deterrent (di-n-butyl phthalate) into a spherical, nitroglycerin-containing nitrocellulose matrix was studied. It was concluded that the final concentration profile could best be explained by a diffusion with interaction mechanism. Based on this mechanism, a method for calculating the depth of deterrent penetration is presented.     

Determination of Deterrent Profiles in Nitrocellulose Propellant Grains Using Confocal Raman Microscopy

The diffusion profile of dinitrotoluene deterred nitrocellulose based small arms propellants is investigated with Confocal Raman microscopy. The diffusion profile in all samples was found to be non‐Fickian Case II diffusion – a steady concentration with a sharp drop. Diffusion depth from the outside surface was found to be much greater than the interior perforation surface. A strong correlation was found between the perforation size of samples and their inside edge diffusion depth, while the outside surface was found to be more dependent on total diameter and deterrent concentration. Samples were also artificially aged to investigate movement of the deterrent over time.     

Density functional theory and molecular dynamic investigations on the energetic and mechanical properties of nitrocellulose/nitroglycerin/pentaerythritol diazido dinitrate composites

Experimental researches stated that pentaerythritol diazido dinitrate (PDADN) may be used as an energetic plasticizer in propellants. To explore whether PDADN is an effective energetic additive of the nitrocellulose/nitroglycerin (NC/NG) double‐base propellant, in this study, various NC/NG/PDADN composites were constructed and investigated using the density functional theory and molecular dynamic methods. Results show that when the content of PDADN is less than about 20%, PDADN can increase the interactions between NC and NG and improve the mechanical properties of NC/NG; but when the content exceeds 20%, the interactions between NC and NG are weakened and the mechanical properties decrease. The composite with a mass ratio of 72.5/22.6/5.0 (NC/NG/PDADN) has the optimal mechanical properties. However, PDADN in this formula does not improve the energy output. As a whole, PDADN can be used as a plasticizer, but not an effective energetic plasticizer of NC/NG. This investigation provides a theoretical evaluation of using PDADN as an additive in the double‐base propellant and gives a practical guidance for designing the NC/NG/PDADN formula. POLYM. COMPOS., 38:192–198, 2017. © 2015 Society of Plastics Engineers     

Research progress of microbial decomposition of nitroglycerine and nitrocellulose

硝酸酯类物质（如硝化甘油和硝化棉等）是有机羟基基团与硝酸缩合的产物,在军事工业上有非常广泛的用途。由于它们并非天然存在的物质,且有爆炸等潜在危害,故不能直接排放到环境中。作为地球生物化学循环中分解者的微生物对硝酸酯类物质的生物降解起着很大的作用,本文将对硝化甘油和硝化棉的生物降解研究进展进行综述。     

Autoradiographic determination of the di-n-butyl phthalate concentration profile in a nitrocellulose matrix

The concentration profile of a deterrent (di-n-butyl phthalate) which had been diffused into a nitrocellulose sphere (ball propellant) containing nitroglycerin was studied by means of autoradiography. Results indicate a level concentration part way into the sphere with an abrupt dropoff in concentration. An explanation for this type of concentration profile is offered based on hydrogen bonding of the deterrent carbonyl group with unesterified hydroxyl groups in nitrocellulose.     

Sorption of diethyl phthalate by nitrocellulose fibers

The manner in which diethyl phthalate (DEP) is absorbed into nitrocellulose (NC) fibers has been observed microscopically. The movement of pure DEP into dry fibers proceeds by capillary motion up the central canal (lumen) and through microcracks between fibrils. Attack, measured by a large change in birefringence, spreads from these foci, and within the time scale of the experiment there is little interaction with the primary (outer) wall of the fiber. If, however, the lumen and other capillary passages are blocked by water or other liquid, then attack proceeds evenly from the outer wall and a sharp boundary between swollen and unswollen material moves at a uniform speed towards the center of the fiber and appears to be unaffected by the fibrillar structure (Case II swelling). If the supply of DEP to the surface is interrupted, this boundary becomes immobile, and the concentration of DEP in the swollen layer is that which is just sufficient to saturate residual un-nitrated hydroxyl groups on the NC. Reducing the activity of the DEP by admixture with benzene results in similar sharp boundaries, presumably because capillaries become blocked with spent diluent. Apart from capillary action, movement is always perpendicular to the fiber axis.     

Oxygen Transport in Aluminum Nitride Substrates

The diffusion of oxygen in commercially available aluminum nitride substrates has been studied by performing interdiffusion-type experiments. The diffusion of oxygen both within AlN grains and along grain boundaries was investigated. By using as-received AlN substrates and an electron microprobe as an analytical tool, it was found that the rate of oxygen diffusion along grain boundaries was strongly influenced by the presence of impurities and/or other phases at these boundaries. The diffusion of oxygen within AlN grains was studied between 1600° and 1900°C in a flowing nitrogen atmosphere by using secondary ion mass spectrometry (SIMS) for determining oxygen concentration profiles. The chemical diffusion coefficient of oxygen in the AlN lattice as a function of temperature is described by the equation The oxygen concentration profiles determined by SIMS also show a contribution from diffusion along grain boundaries. Therefore, it was possible to determine values for the product δD'_o (δ= width of grain boundaries, D'_o= grain boundary diffusion coefficient of oxygen).     

纳米氧化铁的制备及其对吸收药热分解催化作用的研究

用室温湿固相反应制备了纳米氧化铁，并进行了表征，用BSC研究了纳米氧化铁对吸收药（耠化棉吸收硝化甘油的混合物，NC／NG）热分解反应的催化作用，并提出了该催化反应的机理，实验结果表明，纳米氧化铁能有效地催化吸收药的热分解。     

纳米氧化镧对吸收药热分解的催化作用

研究了纳米氧化镧对吸收药(硝化棉吸收硝化甘油的混合物,NC／NG)热分解反应的催化作用,并提出了形成过渡态配合物的反应机理。实验结果表明,纳米氧化镧能有效地催化吸收药的热分解。     

Formulation and Characterization of a New Nitroglycerin‐Free Double Base Propellant

Double base propellants composed of nitrocellulose (NC) and nitroglycerine (NG) are widely used. However, the inclusion of liquid NG presents both stability and performance problems: the NG may migrate from the propellant in storage, and it softens the propellant at high inclusion levels. In this work, the novel nitrate ester 1,4‐dinitrato‐2,3‐dinitro‐2,3bis(nitratomethylene) butane (SMX) is considered as a replacement for NG in a double base propellant. Thermochemical calculations indicate improved performance when compared with the common double base propellant JA2 at SMX loadings above 40 wt‐%. Also, since SMX is a room temperature solid, migration may be mitigated. Both unplasticized and plasticized propellants were formulated to enable the study of the interaction of SMX with nitrocellulose. Thermal analysis of unplasticized propellant showed a distinct melt‐recrystallization curve, which indicates that a solid phase solution is being formed between SMX and NC, and that SMX would not act as plasticizer. Analysis of propellant prepared with diethyleneglycol dinitrate (DEGDN) plasticizer indicates that the SMX is likely dissolved in the DEGDN. The plasticized material also showed similar hardness and modulus to JA2. Safety characterization showed that sensitivity is similar to JA2. In short, replacing NG with SMX results in a new family of propellants with acceptable safety characteristics and which may also offer improved theoretical performance.     

Volatility of NENA and Other Energetic Plasticizers determined by thermogravimetric analysis

Thermogravimetric 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 problem.     

Polarization colors of nitrocellulose

The polarization colors of nitrocellulose (NC) fibers show an orderly progression from gray-white at 11.0% nitrogen (N) through first-order whites, yellows, and reds to second-order blue at 12.6% N. At higher levels of nitration, the polarization colors revert back to first orders with fibers containing 13.1% N showing gray changing to intense white at 13.5% N. The length-positive and length-negative character of NC fibers also changes with the degree of nitration. Fibers nitrated to about 12.4% N are optically neutral and become increasingly positive with a decrease in the level of nitration and increasingly negative as the level of nitration increases. This optical property and the polarization colors of NC provide much information about the level and range of nitration of NC fibers.     

环氧氯丙烷改性水性硝化纤维乳液的制备及性能

以硝化纤维(NC)、异佛尔酮二异氰酸酯(IPDI)和二羟甲基丙酸(DMPA)等为主要原料,制得自乳化型WNC(水性硝化纤维)乳液;然后以环氧氯丙烷(ECH)为交联改性剂,制成改性WNC乳液胶粘剂。研究结果表明:当w(DMPA)=3.5%、w(ECH)=7%时,改性WNC乳液具有优良的储存稳定性,其胶膜耐水性(吸水率为9.1%)、T型剥离强度(7.1 N/mm)、拉伸强度(14.9 MPa)和断裂伸长率(529.3%)俱佳,柔韧性和耐热性优异。     

Dielectric studies of nitrocellulose-nitroglycerine mixtures

Dielectric measurements are reported over a frequency range from 10 Hz to 10⁷ Hz and over a temperature range from ～220–280 K for nitrocellulose (NC) (12.2% nitrated) with varying levels of nitroglycerine (NG), up to 60 wt% NG. A dipolar relaxation is observed and its variation with concentration of NG, temperature, with the presence of stabilizer and method used in preparation of samples are reported. It is observed that the amplitude of the dipolar relaxation increases slowly with the addition of NG up to ～30%, whereupon it increases markedly with further addition of NG. The activation energy for the relaxation process is similarly observed to be sensitive to the level of NG in the system and depends critically on the concentration up to 30%, whereupon it becomes independent of concentration. Comparison of the dielectric data reported here with absorption measurements and nuclear magnetic relaxation studies indicates that these observations can be interpreted in terms of a critical adsorption model. At low concentrations, the NG is adsorbed onto the surface of the microcrystallite structures present in the NC system. Monolayer coverage is believed to occur at ～30% and the marked changes in the dielectric behaviour are consistent with the formation of a multilayer structure.     

环氧树脂改性水性硝化纤维胶黏剂的研究

以硝化纤维(NC)、异佛尔酮二异氰酸酯(IPDI)、二羟甲基丙酸(DMPA)等为主要原料,制得自乳化型水性硝化纤维乳液,再加入环氧树脂E-44,环氧基与羧基反应制备出环氧树脂改性的水性硝化纤维胶黏剂乳液。通过傅里叶变换红外光谱(FT-IR)、透射电子显微镜(TEM)、热失重分析(TGA)法等测试手段,研究了环氧树脂E-44和DMPA的含量对胶黏剂性能的影响。结果表明,当ω(环氧树脂E-44)=5%、ω(DMPA)=3.5%时,环氧树脂改性水性硝化纤维胶黏剂的耐水性、耐热性和柔韧性优异,粘接强度可达7.7 N/mm。     

电晕场作用于棉纤维素对硝化纤维素性能的研究

采用直流电晕场预处理精制棉纤维素，将N2O5-HNO3硝化电晕场作用后的棉纤维素，测定硝化纤维素的黏度和含氮量。结果表明电晕场对棉纤维素的作用时间从3min到720min时，硝化纤维素的黏度从0．320Pa．s降至0．0312Pa．s，含氮量保持不变。棉纤维素电晕场作用时间与硝化纤维素黏度之间的关系为η=30＋883／t。在硝化和电晕场条件一定时，电晕场作用时间对硝化纤维素的含氮量及氮量均匀性没有影响。     

Fabrication and mechanism study of the nitrocellulose aqueous dispersions by solvent displacement method

The traditional preparation methods of nitrocellulose emulsion have many problems, such as high emulsifier content, complex preparation processes, or the need for high energy-consuming emulsification equipment. To address these issues, in this paper, the emulsifier-free NC dispersion was successfully prepared by a simple, low-energy solvent displacement method for the first time and the formation and stabilization mechanism of NC nanoparticles was also thoroughly investigated. The formation mechanism of the NC particles based on the “nucleation and aggregation” and the stabilization mechanism of the NC aqueous dispersions based on the electrostatic repulsion of anions were proposed and supported by experimental results. At the same time, we achieved effective control of the solid content of the NC dispersion by vacuum concentration. The obtained NC dispersion had a large range of adjustable sizes (63.82–143.43 nm), uniform size distribution (PDI < 0.2), a wide range of tunable solid content (0.5%–16%), and good stability (zeta potential < −20 mV), which has potential application in adhesives and coatings as promising candidates for traditional NC organic coatings.     

Investigation of the Decomposition Mechanism and Thermal Stability of Nitrocellulose/Nitroglycerine Based Propellants by Electron Spin Resonance

Nitrocellulose based (NC) and nitroglycerin based (NG) propellants often have a fixed acid and water content during the manufacturing time. After manufacture, the quantity and ratio of acid/water will continue to vary depending upon the conditions of storage and operation. The level of variation depends on many factors such as loading density, temperature, volume of ullage and sealing condition of the containing cartridge, just to name a few. As described in this paper and other literature, the degradation mechanisms and aging processes of NC/NG based propellants are extremely complicated. This paper describes the details of the application of Electron Spin Resonance (ESR) to study if the free‐radical mechanism is involved in the decomposition of nitrocellulose and nitroglycerin. Due to the high free‐radical intensity possessed by the propellant composition, we believe that a π complex intermediate may be formed between DPA and NG and/or NC. The formation of a π complex intermediate is not preferred because it may enhance the rate of decomposition of nitrate esters.