The Nitroglycerin Content Distribution in the coating of the solid propellant and the service life prediction of the charge

In this paper the distribution of the nitroglycerin (NG) content in the coating of solid double-base propellant charge during various time at three aging temperatures were found by using thermogravimetric analysis (TG), and the separation and cracking of the coating were observed. The results showed that the differences of NG contents in the coating are significant and are a main reason giving rise to the separation and cracking of the coating. A empiric functional relation of NG content distribution in the coating to the thickness and aging time and temperature was obtained from measured data. On the basis of the NG contents in the boundary layer of the coating contracted with the propellant and times of separation or cracking of the coating. The service life of the charge was predicted.     

硅烷偶联剂在环氧涂料中的应用

本文对硅烷偶联剂的水解特性，以及对硅烷偶联剂直接添加到环氧涂料中形成的涂层与钢铁基材的附着力进行了研究。研究发现硅烷偶联剂水解能力很强且容易在涂层与基材之间形成化学键作用；将硅烷偶联剂直接添加到环氧涂料中能够显著地提高涂层对钢铁基材的附着力。     

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.     

Migration of additives toward the surface during aging of epoxy coating by infrared spectroscopy

This research highlights the application of multi‐angle attenuated total reflection (ATR) infrared (IR) spectroscopy method in investigating the migration of additives from the bulk toward the surface which happens in the epoxy coating. Concentration profiles of additives such as low molecular polyamide 651 (LMPA 651) and 2,4,6 ‐ tris (dimethylaminomethyl) phenol (DMP‐30) were studied. Analysis of the shape of the additives concentration profiles revealed the existence of enrichment region and indicated the migration phenomenon of additives in epoxy coating during natural aging and accelerated aging processes. The changes of the additives concentration determined by the ATR‐IR method were consistent with the results obtained by FTIR analysis and gravimetric analysis. The result shows that the ATR‐IR method is very promising for investigating the surface chemical changes in epoxy coating due to its nondestructive testing, conveniency, and high efficiency. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40051.     

硝化甘油/1,2,4-丁三醇三硝酸酯混合酯的高效液相色谱分析

混合硝化法制备硝化甘油/1,2,4-丁三醇三硝酸酯混合酯(NG/BTTN)已经实现工业化生产,为满足工业生产的需要,建立了利用高效液相色谱仪测定NG/BTTN混合酯中NG和BTTN含量的方法.该方法简单快速,标准偏差≤0.46％,相对误差≤0.49％,具有重复性好、准确度高的优点.能够满足生产的需要,实现对混合酯中NG和BTTN含量的准确测定.同时对外标法和色谱峰面积归一化法进行了对比.     

SDS-PAGE法分离和表征明胶中不同构象

仔细分析已发表的文献表明,迄今为止用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)测定明胶分子量分布仅限于分出<α、α_1、α_2、和β组份,而γ及>γ的组份未能检出,也就是说,分子量大约30万以上的组份未能进入凝胶板内(以下简称“入板”)。这对明胶构象的全分析和对明胶质量的判断都是一个严重的缺陷。本文主要探讨和研究了γ及>γ组份的入板问题。所采取的办法有:有效地控制丙烯酰胺和甲叉双丙烯酰胺(交联剂)的相对含量,选择合适的交联度梯度和孔径大小,使之既适用于α和β组份迁移,也能让γ及>γ的组份入板。此外,在小交联度和大孔径情况下,还能符合凝胶板对凝胶强度的基本要求。实验结果表时,操作过程缩短,分辨率改善,成功地得到了从几万到30万以上的分子量分布的明胶全部构象的图谱。     

Qualitative Assessment of Nitroglycerin Migration from double-base and composite modified double-base rocket propellants: Concepts and methods of prevention

Several concepts explaining the phenomenon of the nitroglycerin migration from DB and CMDB propellants to the inhibitor, are presented in this review. In the light of these concepts and the data available in the literature, methods to prevent/reduce NG migration are also discussed.     

Electrochemical performance of pyrolytic carbon-coated natural graphite spheres

Natural graphite (NG) spheres were coated by pyrolytic carbon from the thermal decomposition of C₂H₂/Ar at 950 °C in a fluidized bed reactor. Scanning electron microscopy and secondary electron focused ion beam (FIB) images clearly showed that a pyrolytic carbon layer with a thickness of ∼250 nm was uniformly deposited on the surface of the NG spheres. Electrochemical performance measurements for the original and coated NG spheres as anode materials of a lithium-ion battery indicated that the first coulombic efficiency and cyclability were significantly improved in the coated sample. The reasons for this were investigated by analyzing structural characteristics, specific surface area, pore size distribution, and solid electrolyte interphase (SEI) film. Using a FIB workstation, we demonstrated, by cross-section imaging of a coated NG sphere that had experienced five electrochemical cycles, that the SEI film formed on the non-graphitic pyrolytic carbon surface became thinner (60-150 nm) and more uniform in composition compared with that on the surface of uncoated NG spheres; and the formation of an “internal SEI film” inside the NG spheres was also remarkably suppressed due to the uniform coating of pyrolytic carbon.     

Estimation of the impact in the air quality by the use of clean fuels (fuel oil versus natural gas)

The extended use of fuels with high sulfur content (fuel oil) in the electric power industry represents one of the biggest concerns on air quality currently in Mexico. The organic sulfur compounds in the fuel oil are oxidized as SO_x during combustion, causing high concentration at the surface level near the releasing point. Shifting towards cleaner energy is crucial, however natural gas (NG) production is currently scarce and substantial investment is required to assure the NG supply to replace the fuel oil. Large investments should be made by the public and private sectors to replace heavy fuel oil use by NG. In order to support decision takers, this work assess the air quality impact due to cleaner energy use and determine the optimal NG and fuel oil mixture required to reduce substantially the SO₂ concentration. The dispersion model was applied to compare, against a base case, a set of artificial emissions scenarios with different fuel oil and NG mixtures. The model was previously validated against SO₂ field measurements performed at an Industrial Corridor, Mexico. The results show that increasing 40% the NG consumption, the SO₂, concentration in the air is reduced in 90%, therefore not further NG increasing is needed.     

Use of reactable light stabilizers to prevent migration and to improve durability of coatings on plastic substrates

One of the challenges of coating plastic substrates for exterior automotive applications involves the tendency for light stabilizers, which inhibit UV degradation of the coating, to migrate out of the topcoat and into the underlying plastic substrate. The consequent depletion of the stabilizer from the topcoat could account for significantly poorer durability for coatings applied on plastic than on a nonpermeable substrate such as steel. These studies investigate the migration of both nonreactable and reactable UV absorbers (UVAs) and hindered amine light stabilizers (HALS) in fully formulated 2K urethane coatings applied on thermoplastic olefin (TPO) and steel substrates. Extensive migration of the nonreactable stabilizers occurs during accelerated exposure of the cured coating, and this migration correlates with poorer performance on TPO. Functionalization of the stabilizer with a group which covalently reacts into the coating will prevent much of this migration, and the improved degree of retention of the reactable light stabilizers in the topcoat correlates with improved performance on TPO substrates. In addition, stabilizer variables, such as the type and extent of functionalization as well as their chemical structure, have an effect on both the migration and performance of the stabilizers.     

DRYING OF A PAPER COATING : EXPERIMENTAL STUDY AND MODELLING

This research deals with the physical mechanisms that occur during drying of a paper coating. A study at the local scale of the drying of a paper coating coupled with natural binder (starch) migrations is carried out. In this aim, drying experiments have been realized and lead to the determination of drying kinetics, time evolution of moisture content profiles, and starch concentration distribution at the end of drying. The results obtained allow the modelling to be validated. This model, which is based on diffusive liquid transport, takes into account the shrinkage of the coating and the migration of the different solid components during drying. It leads us to suggest that starch migration occurs until the coating is totally consolidated.     

Failure modes in organic coatings studied by scanning acoustic microscopy

Scanning acoustic microscopy (SAM) has been found to be well suited to study physically and chemically induced changes and defects in polymer coatings exposed to corrosive environments. In this work, SAM was used to investigate sub-surface migration and blister formation in polymer coatings of different layer structure after exposure to a corrosive solution. Two model systems consisting of base coat and clear coat on steel substrates where studied. The time evolution of sub-surface migration fronts and blister initiation and their growth were investigated by analysing SAM images after different exposure times. Depending on the layer structure, it was possible to differentiate between transport of the electrolyte solution (i) through the coating and (ii) along the coating/substrate interface. Samples without clear coat typically showed randomly distributed blisters at the coating/substrate interface, irrespective of the location of initial defects. The random distribution of blisters is related to diffusion of the electrolyte solution through the coating layer followed by “nucleation” at weak spots of the substrate, at the interface between polymer and substrate or within the polymer. In contrast, samples with a clear coat acting as a diffusion barrier showed a sub-surface migration front of 2–4 μm height, propagating along the coating/substrate interface, starting at initial defects. The linear propagation of this front cannot be explained by Fickian diffusion and is discussed in terms of an accelerated diffusion or crack growth kinetics. Since blistering started only at regions, where the migration front has already passed, the presence of electrolyte solution or water at the coating/substrate interface was found to be a prerequisite for the nucleation of blisters.     

Effects of nano-graphene on the physico-mechanical properties of bagasse/polypropylene composites

This study was aimed at identifying the best approach of incorporating nano-graphene (NG) into bagasse/polypropylene composites to enhance their mechanical and physical properties. The composites with different NG contents were produced by melt compounding in a twin-screw extruder and then by injection molding. The mass ratio of the bagasse flour (BF) to polymer was 15/85 and 30/70 (w/w). Water absorption, thickness swelling, tensile strength, bending characteristics, impact strength and morphological properties of the produced composites were evaluated. In general, applying NG would improve mechanical properties of the composites. The mechanical test results indicated that when only 0.1 wt % of NG was added, tensile and flexural properties reached their maximum values, while the notched impact was slightly decreased. The composites containing 0.1 wt % NG and 30 wt % BF exhibited the highest tensile, flexural and notched impact strength values. Although incorporating NG into the polymer matrix effectively improves mechanical properties, this improvement comes at proper nanofiller loading (0.1 wt?%). Addition of NG almost did not change the average water uptake and thickness swelling, compared to the control (without NG) samples. Morphological study confirmed that high contents (0.5–1 wt?%) of NG were easily agglomerated. Thermal analysis showed slight increase in thermal stability of WPCs after incorporation of NG particles. In addition, it was found that the effect of BF was notable in material properties of the composites.     

Change of the Structure of a Can Coating during Contact with Food Simulants: an ESR Study

In relation to the study of interactions between food and coated aluminium cans, structural features of a vinylic organosol were studied by electron spin resonance, using amino-oxyls as probes. Two transitions could be observed which were assigned to the poly(vinyl chloride) (PVC) and the epoxy phases. The influence of contact of simulants on the coating was studied using the spin probe method, by monitoring both migration into the liquid and the transition temperatures. © 1997 SCI     

硝化棉在涂料行业应用现状与发展趋势分析

介绍了硝化棉在涂料行业的应用现状及趋势、硝基涂料的优点与广泛应用情况；分析了目前硝基涂料发展面，临的严峻挑战和有利条件，着重指出实现品种低污染化是硝基涂料的主要发展方向。     

Nitroglycerine (NG) Migration to Various Unsaturated Polyesters and Chloropolyesters Used for Inhibition of Rocket Propellants

The kinetics of NG migration has been studied for two groups of resins—Group I: PR-3, FUP-9 and EP-4 and Group II: PAP-1, CPAP-1 and CPAP-2. These unsaturated polyesters and chloropolyesters have been characterized for tensile strength (TS), %-elongation and crosslink density. Further, diffusion coefficient (D), NG migration at infinite time (M_∞) and concentration profiles have also been determined. The data generated on TS, crosslink density, D and M_∞ corroborate the fact that as the crosslink density increases, D as well as M_∞ decrease.     

A New Method for Determining the Vapor Pressure of Nitroglycerine Above Solid Rocket Propellants

Measuring the vapor pressure of compounds such as nitroglycerine (NG) which have a low volatility has not been a straightforward task in the past. There are a wide range of values in the literature for the vapor pressure of NG and furthermore, there is little information regarding the vapor pressure of this compound above solid rocket propellant formulations. We have devised a new method for determining the vapor pressure of NG both above the pure material and solids containing this nitrate ester. The values obtained for pure liquid NG are in good agreement with some previously published values. It was also found that the vapor pressure of this compound is slightly lowered when it is incorporated into solid rocket propellant formulations.     

Studies of the aging effect on the level of isocyanate residues in polyester-based can coating systems

A methyl ethyl ketone oxime-blocked isocyanate was used as a crosslinking agent in the curing of polyester–polyurethane (PEPU) can coatings. The completeness of cure was assessed from the amount of residual (un-reacted) isophorone diisocyanate (IPDI) trimer that was presented in the coating after curing. This amount of residual trimer depended strongly on the temperature at which the curing was undertaken and time given for curing. The degree of cure was also assessed, correlating with the reduced IPDI trimer migration potential. The amount of residual IPDI trimer that was extractable from a typical PEPU coating rose markedly (15- to 20-fold) if the wet coating was aged up to 6 months before use. The presence of a TiO₂ pigment increased the aging effect. An aluminum flake pigment had an even greater effect. The TiO₂ pigment increased aging by different degrees according to the type of surface modification that had been applied to the pigment. The grade having the greatest alumina content, as a result of surface modification, gave the greatest aging. The undesirable effects of aging were counteracted by the addition of more catalyst to the aged coating just before the coating was used to coat panels. Deactivation of the acidic polymerization catalyst system (based on organotin compounds) is thought to be the cause of this aging. These findings have allowed improvements to be made to the specifications of the pigments and the catalysts used, with respect to the consistent industrial production of low migration coatings.     

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.     

硝化甘油脉冲输送技术的应用

介绍一种硝化甘油脉冲输送装置以及计算和测试水脉冲与硝化甘油脉冲的方法。通过理论计算 ,可以精确确定水段和硝化甘油段的输送时间。该法在实际生产中得到了应用 ,并取得了较好的效果