Nitrocellulose Fibers Research Articles

Surface modification of nitrocellulose by interfacial self-assembly of metal-phenolic network for enhanced thermal stability and eco-friendly propulsion energy

Metal-phenolic networks (MPNs) have received widespread interest owing to their ability to incorporate metal ions and phenolic ligands in a modular manner. However, the effect of MPNs on nitrocellulose (NC), an energetic material for propulsion, has not been extensively investigated. Herein, we fabricated MPN-coated NC fibers (NC@MPN) and confirmed the successful coating and homogeneous distribution of MPN on the surface of NC through Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–visible spectroscopy, scanning electron microscopy (SEM) and Energy Dispersive spectroscopy (EDS). The thermal stability of NC was enhanced as evidenced by differential scanning calorimetry (DSC), accelerating rate calorimetry (ARC) and the ignition point test. The thermal decomposition activation energy of NC@MPN can reach 200.73 kJ•mol−1, 7.50 % higher than that of NC primitive fiber (186.72 kJ•mol−1). The ARC tests demonstrate that the implementation of MPN coating prolonged the time of entering the adiabatic section by 5.4 °C and the forecast temperatures for TD8 and TD24 have increased by 4.6 and 4.8 °C, respectively. Additionally, the ignition point was also raised by 2 °C. The aforementioned three experimental results provide evidence for the enhanced thermal stability conferred by MPNs. Besides, thermogravimetric analysis (TGA) results demonstrate a reduction in the residue from thermal decomposition. The present study presents a simple and robust coating strategy for the modular surface engineering of energetic materials, which significantly improves thermal stability and reduces the residues of thermal decomposition.

The influence of solvent selection on nitrocellulose-based, perchlorate-free red-and green-light illuminants

ABSTRACT Nitrocellulose (NC) has been used since the late 1800ʹs in numerous energetic formulations; however, the effect of processing agents (solvents, etc.) on performance has not been thoroughly detailed. For illuminate applications, this is critical as spectral purity and dominant wavelength must meet specifications. In this effort, six processing agents (water, ethanol (EtOH), isopropyl alcohol (IPA), ethyl acetate (EtAc), acetone, and tetrahydrofuran (THF)) are evaluated and the effect they have on the NC fibers and subsequent performance is detailed. XRD and FTIR analysis indicates that the choice of processing agent directly affects the molecular integrity of the NC fibers due to the inhibition of NO2 bonds as well as freeing of hydrogen bonds between polymer chains during solubilization. Time-step FTIR analysis indicated that the weak nitrate ester bond (RCH2-ONO2) is targeted when processed in tetrahydrofuran, ethyl acetate, or acetone, and if heavy solvent interaction occurs, can lead to the autocatalytic decomposition of NC, when heat treated at 110°C. Spectral performance is detrimentally impacted as a result of such interactions. While all six processing agents for red-light illuminant formulations met the military requirements (i.e., spectral purity and wavelength), only ethanol and isopropyl alcohol processed formulations met the military required wavelength of 540 ± 20 nm for green-light illuminants. The IPA processed formulations exhibited the best results with spectral purity values of 69.0% and 94.8% for green and red-light illuminants, respectively.

Effects of Different Nanocarbon Materials on the Properties of Al/MoO3/NCM Thermite Prepared by Electrostatic Spinning.

In order to improve thermal conductivity, energy performance, and combustion performance of the aluminum-containing thermite, nanocarbon materials were added to thermite. Aluminum/molybdenum and trioxide/nanocarbon materials (Al/MoO3/NCM) were fabricated by electrostatic spinning technology. The Al and MoO3 particles of the nAl/MoO3/NCM thermite are much smaller than nitrocellulose (NC); thus, the two components can be better attached to NC fibers. Results on thermal conductivity demonstrated that the addition of NCM can improve the thermal conductivity of Al/MoO3, and the addition of reduced graphene oxide (RGO) has a more significant impact on thermal conductivity. Energy performance analysis results indicated that the energy performance of Al/MoO3/NCM thermite spinning is the best when the value of combustion oxygen equivalent ratio (Φ) is 0.90–1.00. The combustion performance results show that the addition of NCM can significantly increase the combustion rate of thermites, and the addition of RGO improves its combustion rate the most, followed by carbon nanotubes (CNT) and nanoflake graphite (NFG) being the lowest. By changing the shape of the Al/MoO3/NCM charge and the internal composition of the charge, the sensitivity of the agent can be adjusted, and the matching performance and use performance of the electric igniter can be improved.

A Hybrid Paper and 3D Printed Microfluidic Platform for Electrochemical Detection of Ag-Labeled Magnetic Particles

Here we present a hybrid microfluidic device (hyFlow) composed of a disposable paper electrode and a three-dimensional (3D) printed plastic chip for the electrochemical detection of a magnetic bead-silver nanoparticle (MB-AgNP) bioconjugate. Detection of micron-size magnetic conjugates in a paper-only fluidic device is a challenging task. Typically, these devices operate by capillary flow or use paper hollow channels and suffer from flow issues due to entrapment of MB conjugates in cellulose/ nitrocellulose fibers. The hyFlow system was designed to minimize such issues and transport the MB conjugate to the electrochemical detection area without using a syringe pump. Moreover, this device is capable of detecting the MB-AgNP conjugate in both preformed (off-chip) and in-situ formed (on-chip) formats. This portable device can store dried assay reagents in a buffered matrix containing 10% sucrose and 10% D(+)-trehalose and successfully resolvate and mix the reagents in less than 2 min to detect electrochemically. The hyFlow system could detect AgNP labels of preformed MB-AgNP conjugates down to concentrations as low as 12 pM, representing an estimated AgNP coverage of 22 AgNPs per MB.

Modification of a nitrocellulose membrane with nanofibers for sensitivity enhancement in lateral flow test strips.

Lateral-flow analysis (LFA) is a convenient, low-cost, and rapid detection method, which has been widely used for screening of diseases. However, sensitivity enhancement in LFA is still a focus in this field and remains challenging. Herein, we propose an electrospinning coating method to modify the conventional nitrocellulose (NC) membrane and optimize the liquid flow rate for enhancing the sensitivity of the NC based LFA strips in the detection of human chorionic gonadotropin (HCG) and luteinizing hormone (LH). It can be seen that coating the NC membrane with nitrocellulose fibers could obtain a NC based strip with HCG and LH detection limits of 0.22 and 0.36 mIU mL−1 respectively, and a quantitative linear range of 0.5–500 mIU mL−1. The results show that electrospinning is effective in modifying conventional NC membranes for LFA applications.

Electrospun nitrocellulose membrane for immunochromatographic test strip with high sensitivity.

The main goal of this work is to develop an economical, portable, disposable, and reliable point of care paper biosensor based on visualization, which can be used to detect viruses, bacteria, and proteins. However, the sensitivity of immunochromatography test (ICT) strips based on nitrocellulose to target detection has always been a problem. Here, we use anelectrospun nitrocellulose (ENC) fiber membrane instead of traditional nitrocellulose fiber membrane to construct ICT strips for early pregnancy detection. By proper selection of the diameter of theENC fiber to adjust the pore size, porosity, and morphology of the membrane, ICT strips with low flow rate and high protein loading were obtained. Based on these properties, a convenient and sensitive method for the colorimetric determination of human chorionic gonadotropin was developed. Under the optimal conditions, the detection limit of ICT based on ENC membrane is 10mIUmL-1 (S/N = 3), the linear detection range is 5-1000mIUmL-1, and the linear relationship is Y = 0.0434 X - 0.0136 (R2 = 0.9802). In addition, the test striphas good specificity and stability, and will not produce false-positive results. Graphical abstract.

Supercritical Antisolvent Processing of Nitrocellulose: Downscaling to Nanosize, Reducing Friction Sensitivity and Introducing Burning Rate Catalyst.

A supercritical antisolvent process has been applied to obtain the nitrocellulose nanoparticles with an average size of 190 nm from the nitrocellulose fibers of 20 μm in diameter. Compared to the micron-sized powder, nano-nitrocellulose is characterized with a slightly lower decomposition onset, however, the friction sensitivity has been improved substantially along with the burning rate increasing from 3.8 to 4.7 mm·s−1 at 2 MPa. Also, the proposed approach allows the production of stable nitrocellulose composites. Thus, the addition of 1 wt.% carbon nanotubes further improves the sensitivity of the nano-nitrocellulose up to the friction-insensitive level. Moreover, the simultaneous introduction of carbon nanotubes and nanosized iron oxide catalyzes the combustion process evidenced by a high-speed filming and resulting in the 20% burning rate increasing at 12 MPa. The presented approach to the processing of energetic nanomaterials based on the supercritical fluid technology opens the way to the production of nitrocellulose-based nanopowders with improved performance.

Electrospinning and thermal characterization of nitrocellulose nanofibers containing a composite of diaminofurazan, aluminum nano-powder and iron oxide nanoparticles

Electrospinning was used to fabricate composite nanofibers based on nitrocellulose (NC), and some additives comprising aluminum nanoparticles, Fe2O3 nanoparticles and diaminofurazan (DAF). The appropriate mechanical properties (such as elasticity, stiffness and tensile strength) accompanied by the suitable combustion rate of these fibers make them attractive for the utilization in the propellant formulations. The results of this work show that the average diameter of electrospun composite nanofibers (NC fibers containing Al/Fe2O3/DAF) is 80 nm. Thermal behavior of the fabricated nanofibers was characterized by DSC technique. The results showed that thermal decomposition of the nanofibers happens at the temperature 190 °C. In this study, two non-isothermal kinetics analysis methods (i.e., Kissinger and Starink) were used to predict kinetic parameters of thermal decomposition, such as activation energy and frequency factor; as well as, thermodynamic parameters (ΔG#, ΔH#, and ΔS#). The results yield activation energies about 219 kJ mol−1 for thermal decomposition of the nanofibers. Moreover, it was found that the thermal stability of Al/Fe2O3/NC nanofibers in the presence of DAF improves and hence it has a positive effect on the safety of this nanocomposite.

Silica aerogel membranes fabricated using removable nitrocellulose scaffolds

Abstract Two different methods were developed to generate silica-based aerogel membranes using nitrocellulose scaffolds. The first method involved incorporating fibers of nitrocellulose (NC) into the sol prior to gelation. NC fibers were either removed using a solvent during aging or calcining after aerogel formation to produce reticulated micron-sized channels in the aerogels. In the second method, an NC lacquer was mixed with the sol, and the mixture separated into a NC-rich phase and a sol-rich phase. The NC phase was subsequently removed from the aerogel using a solvent, creating aerogels with interconnected porosity. Aerogels were prepared from tetraethyloxysilane (TEOS) as a precursor and methyltriethoxysilane (MTES) as a co-precursor. Replacing TEOS with 25 vol% MTES increased the mechanical stability, allowing for greater ease of handling. Additionally, the more open network of the MTES gels led to higher helium gas permeability than that for the pure TEOS gels.

Theoretical and experimental study on the effect of nitrogen content on the thermal characteristics of nitrocellulose under low heating rates

The thermal behavior of nitrocellulose (NC) with different nitrogen contents has been widely investigated in previous works. However, most of the experiments were carried out under high heating rates, a situation in which it is difficult to capture minor changes during the thermal decomposition process. In the present study, the thermal characteristics of NC with different nitrogen contents were theoretically and experimentally investigated using a CALVET heat flux calorimeter C80 at heating rates from 0.2 to 0.8 °C/min. Before thermal analysis, the results of high-precision scanning electron microscopy showed that more cracks and coarser surfaces were detected on NC fibers with higher nitrogen contents. It was found that a “turning point” was detected on the heat flow curves of NC with higher nitrogen contents. Furthermore, the heat flow curves of NC transformed from “bell shape” to “right triangles” with increases in the nitrogen content, which suggested that NC with high nitrogen contents exhibited autocatalysis characteristics under low heating rates. This characteristic was also confirmed by the isothermal experiment results that showed the autocatalytic properties became increasingly obvious by increasing the isothermal temperature. Moreover, the relevant chemical kinetic and thermodynamic parameters were obtained. The heat of the reaction (ΔH) increased and the activation energy values in the initial stages of NC decomposition decreased as the nitrogen content was increased. Furthermore, the critical explosion temperature (Tb), which is as an important parameter to evaluate the thermal hazard of NC, decreased by elevating the nitrogen content.

The Thermal Properties of Nitrocellulose: From Thermal Decomposition to Thermal Explosion

ABSTRACTNitrocellulose is an extremely dangerous explosive substance, which will decompose at a relatively low temperature. This article studied the thermal properties transformed from thermal decomposition to thermal explosion for a less violent nitrocellulose sample (nitrogen content: 10.92%). Four experiments were implemented: XPS analysis and SEM analysis, DSC-TG analysis, and small-scale thermal explosion experiment. From XPS analysis and SEM analysis, high temperatures led to the decrease of N1s and O1s (O-NO2 bond) and the break or even “melt” of the nitrocellulose fibers. The results demonstrated that nitrocellulose would become more unstable if it was exposed to high temperature. From the DSC-TG analysis and small-scale thermal explosion experiment, the upper critical ambient temperatures (UCATs) of the nitrocellulose were calculated. The UCATs of the nitrocellulose sample would decrease from 132.5ºC to 96.4ºC with the dimensions increased from 0.1 m to 1.6 m. The results demonstrated that the risk of spontaneous combustion and thermal explosion increased significantly with the increase of the volume of nitrocellulose.

Nitrocellulose Synthesis from Miscanthus Cellulose

AbstractThe possibility of synthesizing nitrocellulose (NC) from an easily renewable non‐woody feedstock, Miscanthus, is demonstrated herein. Nitration of Miscanthus cellulose with commercial mixed acid was found to afford high‐quality NC: 11.85 % nitrogen content, 18 cP viscosity of 2 % NC‐acetone solution, 97 % solubility in alcohol‐ester mixture, and 0.11 % ash content. The Miscanthus NC structure and fibers were characterized by analytical techniques such as SEM, IR spectroscopy, TGA/DTG, and 13C NMR spectroscopy. The Miscanthus NC is comparable in quality to basic NC types used for the manufacture of films, membranes, lacquers, nail polish, liquid bandage, artificial silk and skin.

Electrospun nanofiber-based nanoboron/nitrocellulose composite and their reactive properties

Nanometal fuels have a great potential in energetic field for their high reactivity and their low ignition temperature. However, their high surface energy makes them aggregate. In this work, the electrospinning was employed to fabricate the nanoboron/nitrocellulose nanofibers expecting to enhance the reactivity of nanoboron. The results of SEM and TEM show that nanoboron is well dispersed in the nitrocellulose fiber matrix. TG–DSC confirms that the nanoboron in the fibers reacted more drastically than pure nanoboron and nanoboron/nitrocellulose powders resulted from the thermal analysis. Combustion propagation velocity shows that the presence of nanoboron in nitrocellulose fibers causes the faster and more intensive burning than the mechanical mixture of nanoboron and nitrocellulose.

A novel method for blood-typing using nitrocellulose.

Blood wicking in its steady-state form, i.e. the uniform distribution of blood cells in plasma, is completely different from that in its coagulated form on a porous surface like paper. The hydrophilic property of the cellulose leads to a significant wicking of the blood cells on paper fibers after rinsing with isotonic solution. The difference in the wicking length of the blood cells in steady state and that in the coagulated form could be considered as a criterion to recognize the blood type in a paper-based kit. However, owing to the molecular structure of the nitrocellulose, a better process occurs while separating the coagulated blood from the steady-state form of cells. Therefore, it is possible to use the nitrocellulose for the blood-typing kit which leads to a simpler way to diagnose a blood type. Two series of experiments were performed on nitrocellulose membrane. First, antibody solutions and blood samples were sequentially absorbed on nitrocellulose strips, allowed to interact, rinsed with an isotonic solution and distilled water, and image processing performed on a digital picture of the remaining blood cells. The efficiency of the agglutinated blood cell fixation was quantified by red color intensity. Then, it was demonstrated that there is no considerable difference in fixation of agglutinated blood cells with rinsing using isotonic and nonisotonic solutions. This fact can be a considerable advantage over paper since it can eliminate the probable mistake from using unisotonic solution for rinsing. Second, owing to the nonwicking property of the blood cells on the hydrophobic nitrocellulose fibers, we employed another diagnostic criterion and investigated nitrocellulose blood-typing prototypes. The nitrocellulose blood-typing kit provides more simple, sensitive and trustworthy assay for rapid blood typing in situations with no access to laboratory facilities.

The thermal decomposition mechanism of nitrocellulose aerogel

Nitrocellulose (NC) aerogel was prepared by sol–gel synthetic approach and supercritical carbon dioxide drying method as a new energetic matrix for nano-composite energetic materials. Scanning electron microscopy of the NC aerogel reveals that the aerogel is accumulated by nanoparticles with a diameter of 30–50 nm and has nano-porous structure, which makes the thermal behavior of the NC aerogel different from that of the NC fibers. Therefore, the thermal properties of NC aerogel were determined by TG/DSC, which showed that the maximum decomposition temperature and the exothermic peak temperature of NC aerogel decreased 8.2 and 11.4 °C than NC fibers, respectively. By TG/FTIR technology combined FTIR test of the condensed phase, the decomposition mechanism was derived based on the experimental results. The initial reaction of NC aerogel decomposition is the splitting of urethane bond, and then, the scission of –O–NO2 bonds happens. Moreover, the macromolecular chains’ scission site of NC aerogel firstly occurs at –C–O–C– in the ring, while the chains of NC fibers break at –C–O–C– between the rings.

Microstructured Al/Fe2O3/Nitrocellulose Energetic Fibers Realized by Electrospinning

At present, metastable intermolecular composites (MICs) have been widely studied for their potential in high-density energetic materials and nanotechnology, but the relatively low-pressure discharge in a short period of time and the oxidation of Al powders have seriously impeded their applications in rocket solid fuels and explosives. In this work, the authors successfully fabricated microstructured Al/Fe2O3/nitrocellulose (Al/Fe2O3/NC) fibers via simple electrospinning, introducing nitrocellulose (NC), a gas generator to MICs. In view of previous reports, wrapping nAl in NC fibers might reduce their further oxidation during storage. In addition, the thermal properties and elastic modulus of NC fibers were measured before and after adding Al/Fe2O3.

Coating of nitrocellulose for colorimetric DNA microarrays

We report on the modification of a nitrocellulose film with copoly(DMA-NAS-MAPS), a tercopolymer based on N,N-dimethylacrylamide (DMA), N-acryloyloxysuccinimide (NAS), and 3-(trimethoxysilyl)propyl-methacrylate (MAPS). The chains of this polymer, interacting with nitrocellulose fibers, introduce active ester functionalities that promote the covalent binding of short oligonucleotide fragments to the nitrocellulose thin film. Using colorimetric detection, naked eye visible DNA microarrays are developed for easy identification of foodborne pathogens. The fast and robust procedure of nitrocellulose functionalization opens the opportunity to implement this material in disposable analytical microdevices that do not require sophisticated readout systems.

Synthesis of Ultra-Fine Conducting Polyaniline Micro/Nanotubes Using Fiber Template and Their NH3 Gas Sensitivity

We have recently fabricated ultra-fine conducting polyaniline (PANI) tubes with high gas sensitivity. This route includes two steps. Firstly, aniline polymerizes on the surface of a suitable fiber template prepared by electrospun nitrocellulose (NC). Then, the NC fiber template is dissolved and the ultra-fine PANI tubes are obtained. The structure of the conducting PANI tubes is characterized by IR spectrum and wide-angle X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results indicate that the PANI shows the shape of ultra-fine tubes with average inner diameter of 250-350 nm. The wall thickness of the ultra-fine PANI tubes increases with increasing the content of oxidant. The conductivity of the doped PANI tubes is about 6.9 x 10(-2) S. The results of gas sensitivity of the ultra-fine PANI tubes indicate that the PANI tubes can act as "electronic nose" to detect toxic NH3 gas below 20 ppm.

Scanning electron microscope examination of JA2 propellant samples exposed to plasma radiation

Some plasma-exposed samples of transparent (graphite-free) JA2 propellant were examined by scanning electron microscopy. It was found that the plasma-exposed surface of these samples was covered with humps or bubble-like structures. When the samples were cryogenically split, the interior was found to contain numerous open cracks and voids; in a very few cases where the split actually went through a hump/bubble, cracks/voids were found immediately under the hump, suggesting a cause and effect relationship. The inside surfaces of the cracks and voids appeared in some cases to be either (a) smooth and undulating, or (b) about as would be expected if the two sides of the crack had been simply pulled apart; or (c) rough and/or debris-covered. In some type (c) cases they appeared to have been initially rough or debris-covered but to have been at least partially smoothed, possibly by processes involving heat, liquefaction and thermal decomposition. These observations seem consistent with an interpretation involving subsurface penetration of the propellant sample by visible and infrared radiation; this radiation then might cause cracks as a result of uneven expansion due to heating and/or internal gasification due to photochemical and/or thermal decomposition, particularly at sites of small patches of unplasticized nitrocellulose fibers. If these changes also included liquefaction or melting, with or without decomposition, this would also help to understand the smoothing process. In any case, these results suggest that interaction of plasma radiation with the sample is a significant effect. An end-exposed grain of standard, semitransparent JA2 was also examined; in this case the cracks were oriented differently; they extended from holes in the surface into the interior in a direction perpendicular to the surface and parallel to the direction of extrusion.

Thermochemistry of the Binary System Nitrocellulose-s-Diethyldiphenylurea

A method of gelation enthalpy determination of nitrocellulose (NC)+s-diethyldiphenylurea (Centralite 1, C1) binary system was elaborated using the change of Centralite 1 melting enthalpy in the mixture. The heats of C1 melting together with gelation and dissolution of NC fibres were determined by DSC calorimetric methods. A sharp maximum of the gelation enthalpy for C1 mole fraction x C1 max =0.555 suggests that the complex is very stable and one partly nitrated anhydroglucose ring is interacting with about 1.25 C1 molecules. The gelatinization enthalpy maximum equals % MathType!MTEF!2!1!+- % feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqFj0xd9q8as0-LqLs-Jirpepeea0-as0Fb9pgea0db9fr-xfr-x % frpeWZqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqadIeagaqeam % aaDaaaleaaieaacaWFTbGaa8xyaiaa-HhaaeaacaWFnbaaaaaa!3DEB! $$ \bar H_{max}^M $$ =−4.59 kJ mol−1.