Burning Rate Catalysts Research Articles

Preparation, characterization and molecular dynamics of novel pre-plasticized nitrocellulose composite microspheres containing burning rate catalysts

ABSTRACT In this contribution, pristine nitrocellulose (NC) and novel NC/glycidyl azide polymer (GAP) composite microspheres with uniformly dispersed burning rate catalysts, a high degree of roundness and excellent fluidity, were successfully prepared using a solution blending procedure. The burning rate catalysts had an apparent catalytic effect on the thermal decomposition of the novel composite microspheres and promoted their heat release. Furthermore, molecular dynamics simulation was conducted to explore the plasticizing mechanism of GAP. NC/GAP showed improvements in free volume and radius of rotation of 82.14% and a 50.13%, respectively, compared to pristine NC, indicating that GAP molecules had increased mobility in the NC matrix. In addition, the radial distribution function showed that NC/GAP exhibited higher intermolecular intensities from both hydrogen bonding and van der Waals forces compared to those of pristine NC, which was consistent with the value obtained for the average intermolecular interaction energy. The experimental and computational studies showed that there may be good potential for the design and manufacture of novel pre-plasticized NC composite microspheres having low vulnerability and good plasticizing performance for preparation of propellant.

Synthesis, crystal structure and thermal behavior of magnesium 5,5′-bistetrazole-1,1′-diolate hexahydrate complex

ABSTRACT A new energetic green burning rate catalyst, magnesium 5,5′‒bistetrazole‒1,1′‒diolate hexahydrate complex ([Mg(BTO)(H2O)6], 1) was synthesized based on 5,5′‒bistetrazole‒1,1′‒diolate dehydrate (BTO, 2) by the metathesis reaction, and it was characterized by FTIR spectroscopy, elemental analysis (EA), Scanning Electron Microscopy (SEM) and single X-ray diffraction. The thermal decomposition processes of magnesium complex 1 and compound 2 were studied utilizing the TG‒DTA and TG‒MS technologies. Moreover, the sensitivity tests were carried out to evaluate the stability of compound 1 and compound 2. Besides, the DSC was used to evaluate the catalytic effect of magnesium complex 1 on thermal decomposition of cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX), hexanitrohexaazaisowurtzitane (CL‒20) and dihydroxylammonium 5,5′-bistetrazole −1,1′-diolate (TKX‒50). The thermal behaviors indicate that the gaseous products such as NO, CO, N2 are checked from the decomposition of the complex at 320°C. Sensitivity results show that compound 1 is more insensitive to mechanical stimuli than compound 2. The results from DSC and the target line method analyses indicate that [Mg(BTO)(H2O)6] have no effect on the thermal decomposition of RDX, HMX, CL‒20 except for TKX‒50.

Synthesis of ferrocenylated-aminopyridines and ferrocenylated-aminothiazoles and their anti-migration and burning rate catalytic properties

For overcoming the migration problems of ferrocene (Fc)-based burning rate catalysts (BRCs) as well as for enhancing burning rate (BR) of ammonium perchlorate (AP)-based propellants, ferrocenylated-amino pyridines (AP-Fcs) and ferrocenylated-amino thiazoles (AT-Fcs) have been synthesized. The synthesis of AP-Fcs and AT-Fcs was confirmed by nuclear magnetic resonance (1H NMR). Electrochemical properties of these ferrocenylated derivatives were explored by cyclic voltammetry (CV). The BR catalytic activities of AP-Fcs and AT-Fcs on thermal decomposition of AP were examined by thermogravimetric (TG) and differential thermogravimetric (DTG) techniques. Thermal analysis results showed that AP-Fcs and AT-Fcs showed good BR catalytic effects on thermal decomposition of AP. AP-Fcs and AT-Fcs were also applied for anti-migration studies in comparison with catocene (Cat) and ferrocene. It was found that AP-Fcs and AT-Fcs displayed anti-migratory behavior.

Synthesis and combustion catalytic activity of ferrocene‐based energetic compounds

AbstractAmmonium perchlorate (AP) is a common oxidizer in composite solid rocket propellants due to its excellent burning characteristics, good processability, and storability. Owing to their outstanding catalytic effects, ferrocene, and its derivatives have become the most widely used burning rate catalysts (BRCs). The addition of ferrocene and its derivatives to AP rendered performance optimization. In this study, azole‐based ferrocenyl compounds were successfully synthesized. The compounds were characterized by single‐crystal X‐ray diffraction, UV‐vis spectroscopy, and other techniques. The thermal degradation of AP catalyzed by these compounds was evaluated by differential scanning calorimetry and thermogravimetric analysis. Results revealed that the decomposition peak temperature of AP dramatically decreases and that the released heat of AP significantly increases with the new compounds as additives. Hence, the six azole‐based ferrocenyl BR catalysts are favorable for the combustion catalytic activity.

Study on Friction Sensitivity of Passive and Active Binder based Composite Solid Propellants and Correlation with Burning Rate


 Friction sensitivity of composite propellants and their ingredients is of significant interest to mitigate the risk associated with the accidental initiation while processing, handling, and transportation. In this work, attempts were made to examine the friction sensitivity of passive binder: Hydroxy Terminated Polybutadiene/Aluminium/Ammonium Perchlorate and active binder: (Polymer + Nitrate Esters)/Ammonium Perchlorate/Aluminium/Nitramine based composite propellants by using BAM Friction Apparatus. As per the recommendation of NATO standard STANAG–4487, the friction sensitivity was assessed by two methods: Limiting Frictional load and Frictional load for 50% probability of initiation (F50). The test results showed that the active binder based formulations were more vulnerable to frictional load as compared to the formulations with passive binders. Examination of a comprehensive set of propellant compositions revealed that the particle size distribution of Ammonium Perchlorate and burn rate catalysts were the most influential factors in dictating the friction sensitivity for HTPB/Al/AP composite propellants. For active binder/AP/Al/Nitramine composite propellants, the formulation with RDX was found more friction sensitive with a sensitivity value of 44 N as compared to its HMX analog (61 N). The correlation studies of friction sensitivity, burning rate, and thermal decomposition characteristics of HTPB/Al/AP composite propellants is described.

Formation of composite fuels by coating aluminum powder with a cobalt nanocatalyst: Enhanced heat release and catalytic performance

Aluminum (Al) and Cobalt (Co) materials are used as a metal fuel and a burning rate catalyst in solid propellants, respectively. However, micro-sized Al fuel has a poor heat release performance because of inertial surface oxide layers, and a nano-sized Co catalyst tends to agglomerate due to high surface energy and magnetism. In this work, we successfully synthesize a new composite fuel by coating Al fuel with a Co catalyst (Co/Al) via a novel replacement reaction and experimentally investigate its heat release and catalytic performance. Our measurements show that the heat release efficiency of Al powder is greatly enhanced by coating only 4.6 wt% of Co. The high oxidation temperature of the formed composite fuel is advanced by 112 °C, and the heat release is approximately 1.5 times that of the raw Al. The Co/Al composite fuel displays excellent catalytic activity and stability toward the thermal decomposition of ammonium perchlorate (AP), thereby decreasing the high decomposition temperature of AP by approximately 150 °C. To the best of our knowledge, the promoting efficiencies of the high-temperature oxidation of Al and the high-temperature decomposition of AP are higher than those reported in literature. The heat release and catalytic thermal decomposition mechanisms of Co/Al composite fuel are proposed on the basis of experimental phenomena and results. Results confirm that the formation of composite fuel by coating Al powder with a Co nanocatalyst is an effective method to enhance the heat release of Al and the catalytic performance towards AP. The as-obtained Co/Al composite fuel is expected to have wide application prospects in solid propellants.

Novel ferrocene-based 1,2,3-triazolyl compounds: Synthesis, anti-migration properties and catalytic effects on oxidizers during combustion

To tackle high-migratory and high-volatility problem of marketed neutral ferrocene-based burning rate catalysts, twenty-one ferrocene-based 1,2,3-triazolyl compounds (Fc-TAZs) were synthesized by click reaction and characterized completely by NMR, FT-IR, UV–Vis and elemental analysis. In addition, four compounds were structurally confirmed by single crystal X-ray diffraction. TG and DSC analysis showed that the new Fc-TAZs are of high thermal stability. Cyclic voltammetry investigations suggested that more than half of the Fc-TAZs are reversible redox systems. Anti-migration and anti-volatility tests revealed that all the Fc-TAZs display, on comparison with Catocene, extremely low volatility and migration tendency due to the appearance of polar oxygen and nitrogen atoms in their molecules. Catalytic activity tests of the novel Fc-TAZs towards the thermal decomposition of oxidizers, evaluated by TG and DSC techniques, indicated that all Fc-TAZs exert great effects on the thermal disintegration of AP and compounds 5, 7 and 11 can promote the thermal decomposition of HMX during combustion.

Functionalization graphene oxide with energetic groups as a new family of metal-free and energetic burning rate catalysts and desensitizers for ammonium perchlorate

A new family of metal-free and energetic graphene oxide (GO)-based burning rate catalysts (FGO 1–6) with excellent catalytic and desensitization performances for ammonium perchlorate (AP) were synthesized by nucleophilic substitution reaction of energetic functional groups with acylated GO. The chemical structures, thermal stabilities, catalytic properties and desensitization performances of the functionalized GO were determined. It was shown that the functional groups on the nanosheets of GO imparted its energetic performance and thermal stability, and the catalytic properties and desensitization performances were also enhanced. The reduced mass loss rate along with enhanced residues formation indicated significant improvement in thermal stabilities for FGO 1–6 compared with GO. Besides, not only did FGO 1–6 lower the decomposition temperature, but also enhanced the overall heat for the thermal decomposition of AP. The FGO 1–6 decreased the exothermic peak of the high-temperature decomposition process of AP by 88.1, 93.4, 98.3, 85.8, 90.7 and 79.8 °C, corresponding to the decomposition heat of AP increased significantly from 655 to 2707, 2915, 3529, 3002, 3642 and 2718 J g−1, which exhibited better catalytic activity than that of GO. In addition, the mechanical sensitivities of AP/GO and AP/FGO 1–6 mixtures decreased obviously in comparison with pure AP were also obtained. A new family of metal-free and energetic GO-based burning rate catalysts with excellent catalytic properties and desensitization performances for ammonium perchlorate were developed.

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.

HTPB‐Clay Nanocomposites (HCN): An Efficient Burning Rate Catalyst for Composite Propellant

AbstractIn present study, two types of montmorillonite clay, organically modified with polar and apolar moieties, are used, for preparation of HTPB‐clay nanocomposites (HCN) by dispersion of nanoclay in polymer matrix with high shear mixing. These nanocomposites are evaluated in composite propellants for their catalytic effect on decomposition of ammonium perchlorate a work horse oxidizer. Several composite propellant formulations containing 1–3 weight % of nanoclays over binder, were prepared. Along with this, formulations with conventional burning rate catalyst like iron oxide in 1–3 weight % over binder, and formulation without any burning rate catalyst as base composition were also processed. All these formulations were evaluated by means of theoretical prediction, end of mix viscosity, ballistic properties, mechanical properties, sensitivity parameters and thermophysical properties. Experimental results showed that HCN based compositions have lower or comparable end of mix viscosity than base compositions. Further characterization revealed that formulations with 3 weight % of nanoclays over binder have 70 % higher burning rate than base composition as well as 20–25 % higher burning rate than compositions having 3 weight % of iron oxide over binder. Pressure exponent values are determined for 3 to 11 MPa of pressure range and were found to be significantly higher for HCN based compositions (0.33 to 0.7) in comparison to the base composition. Mechanical properties and sensitivity data of HCN based compositions are comparable with base composition. Thermal studies revealed decrease in onset temperature of decomposition of AP with presence of nanoclay which may be the probable cause for enhancement in burning rate.

Thermal analysis of mechanically activated Al-(Fe2O3, MoO3, and MnO2) metastable intermolecular composites

Metastable intermolecular composites (MIC) are among energetic materials that can act as burn rate catalysts in many applications and composition determines how quickly the mixture burns. Such materials can be prepared by the arrested reactive milling (ARM) process. In this study, Al-Fe2O3, Al-MoO3, and Al-MnO2 thermite systems were milled via ARM for 0, 4, and 8 h to evaluate the effects of mechanical activation time and thermite mix on the reaction temperature and intensity, evaluated using DSC analysis. The results of DSC, SEM, and XRD analyses indicated that the morphology and average particle size of as received metal oxides had a considerably effective on achieving reaction initiation and reaction intensity level. It was found that MoO3 powders with a considerably higher average particle size (lower agglomeration) than those of the other oxides, requiring a lower milling time for reaction start with a considerable intensity, while the results obtained for Al-Fe2O3 and Al-MnO2 systems were not promising for achieving a low mechanical activation time and high reaction intensity.

Ferrocene grafted hydroxyl terminated polybutadiene: A binder for propellant with improved burn rate

In this work, iron containing hydroxyl terminated polybutadiene (Fe-HTPB) based binder cum burn rate catalyst has been developed without altering the crucial physical properties of HTPB. Ferrocene, the source of Fe in the Fe-HTPB, has been grafted at the terminal carbons of HTPB to ensure no alternation in microstructure of HTPB which in turn helped in retaining physical properties of pristine HTPB. The structure and the presence of ferrocene as the end cap groups of the Fe-HTPB were confirmed by solid-state NMR and MALDI-TOF-MS analysis. Control over the viscosity and Fe content of the Fe-HTPB was achieved by varying the grafting reaction recipes and conditions. The Fe content, as measured by inductively coupled plasma - atomic emission spectroscopy (ICP-AES) in the Fe-HTPB varied from 0.06% to 0.165% (by weight) and found to be responsible for increasing viscosity of Fe-HTPB from 5857 mPa S to 11,890 mPa S. Non aluminized composite solid propellants (CSPs) with 86% (wt%) ammonium perchlorate loading were prepared using Fe-HTPB as a binder for studying the burn rate efficiency. Burn rates of CSPs made from Fe-HTPB binders were found to be enhanced by ∼125% compared to CSPs of pristine HTPB. At 40 bar pressure, the burn rate of CSPs made from Fe-HTPB and pristine HTPB binders are 20.56 and 9.07 mm/s burn rate, respectively. In addition, all the CSPs made from Fe-HTPB were found to be very stable as their pressure index is less than 0.5.

Synthesis and Characterization of a Dinuclear Nitrogen‐Rich Ferrocenyl Ligand and Its Ionic Coordination Compounds and Their Catalytic Effects During Combustion

Alkylferrocene‐based burning‐rate catalysts (BRCs) exhibit distinct migration tendency and high volatility and thus result in inferior performance of composite solid propellants during their combustion processes. To deal with these drawbacks, a novel dinuclear nitrogen‐rich ferrocene derivative, 4‐amino‐3,5‐bis(4‐ferrocenyl‐1,2,3‐triazolyl‐1‐methyl)‐1,2,4‐triazole (BFcTAZ) and its twenty seven ionic coordination compounds, [M2(BFcTAZ)2(H2O)4]mXn·xH2O (M = Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+ and Pb2; X = polycyano anions), were synthesized and characterized by FT‐IR, UV/Vis, and elementary analysis. Crystal structure of BFcTAZ was further confirmed by single‐crystal X‐ray diffraction and a general molecular structure of the new complexes was proposed. Their high thermal stability was verified by TG technique. Cyclic voltammetry studies suggested that the new compounds are diverse redox systems. Their effects on the thermal degradation of some common oxidizers were measured by DSC technique. The results indicated that most of the new complexes exert great effects on the thermal decomposition of AP, RDX, and 1,1‐diamino‐2,2‐dinitroethylene (FOX‐7) and some of them are more active than catocene. The Cu2+ complexes are among the excellent ones. However, only six compounds have appreciable catalytic activity in the thermal degradation of HMX.

Ferrocenyl Ionic Compounds Containing [Fe(CN)6]3– Anions: Synthesis, Characterization, and Catalytic Effects during Combustion

Twenty‐eight novel ferrocenyl ionic compounds, composed of mononuclear 1‐ferrocenylmethylalkyldimethylammoniums, 1‐ferrocenylmethyl‐3‐alkylimidazoliums, or their dinuclear analogs and [Fe(CN)6]3– anion, were designed and synthesized to tackle significant volatility and migration tendency of ferrocene‐based burning rate catalysts (BRCs) used currently in the composite solid propellants. The new compounds were characterized by UV/Vis, FT‐IR, and elementary analysis. The crystal structures of compounds 2·5H2O and 3·CH2Cl2·4H2O verified the successful preparation of the desired ionic compounds. The TG tests at 70 °C for 24 h revealed that the new compounds exhibit lower volatility than catocene. The cyclic‐voltammetry results suggested that new compounds are quasi‐reversible or irreversible redox systems. TheTG/DSC analyses exhibited that the compounds are of highly thermal stability. Their catalytic effects on the thermal degradation of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), and 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazacyclooctane (HMX) were investigated. The results showed that most of the compounds exert great effects on the thermal degradation of AP and RDX during combustion. 11 and 2 are comparable to catocene in the thermal decomposition of AP and RDX, respectively, and can therefore be used as alternatives of catocene in a composite solid propellant. Some new compounds are unexpectedly active in promoting the thermal disintegration of HMX.

Silicone bridged iron metallocene butadiene composite solid propellant binder: aspects of thermal decomposition kinetics, pyrolysis and propellant burning rate

ABSTRACTPropellant binders are essential components of composite solid propellants (CSP’s) used in launch vehicles and missiles. Binders act as a fuel and contribute directly to the combustion in conjunction with oxidizer particles and metallic fuel apart from imparting structural integrity to the solid propellant grain .The performance of CSP’s are directly related to the burn rate of the propellant. The burn rates of the ammonium perchlorate (AP) propellants are generally moderated using various types of transition metal oxide (TMO) catalysts. However, TMO’s are associated with inherently large dispersions in propellant burn rates and compromise on energetics. One of the most suitable methods for achieving lower dispersion in burn rate is using binders wherein a burn rate catalyst is grafted to the polymer matrix. In the present paper, the thermal decomposition of ferrocene bound hydroxyl terminated polybutadiene (FC-Si-HTPB) grafted to butadiene backbone via hydrosilylation was investigated The thermal degradation mechanism, stability and its effectiveness as burn rate catalyst are the most important aspects for use in CSP’s. The mechanism of decomposition of the neat resin and in combination with AP has been elucidated using pyrolysis gas chromatography–mass spectrometric technique (GC-MS). FC-Si-HTPB exhibits single stage decomposition in the temperature range of 263–491°C. The decomposition of FC-Si-HTPB with AP oxidizer follows a two stage mechanism in the 195–490°C.The char residue was characterized using FTIR, Raman spectroscopy and FE-SEM analysis, which enables to vindicate the mechanism of reaction. The activation energy for the decomposition of HTPB is 283.6 kJ/mol, FC-Si-HTPB is 251.5 kJ/mol and for Fc-Si-HTPB-AP system is 67.1 kJ/mol. The major pyrolysis products of neat FC-Si-HTPB are ferrocenyl derivatives, silylated ferrocenyl derivatives and precursors emanating from polybutadiene backbone. The propellants based on the new binder exhibited an increase in burn rate with iron content and higher fine content. A comparison of propellant burn rate with conventional micron sized ferric oxide exhibited an improvement of 34%.Based on the thermal analysis studies, the thermal endurance of the system was computed to be FC-HTPB> HTPB> FC-HTPB-AP.

Catalytic effects of p-phenylene-bridged methylated binuclear ferrocenes on thermal decomposition of the main component of composite solid propellants

This contribution describes the catalytic activity of homobimetallic complexes derived from p-phenylene on the thermal decomposition of ammonium perchlorate (abbreviated as AP). The complexes, [CpFe-p-Ph-FeCp] (1), [Cp*Fe-p-Ph-FeCp*] (2), [CpFe-p-Ph’-FeCp] (3) and [Cp*Fe-p-Ph’-FeCp*] (4) (with p-Ph: p-Bis(3,4-dimethylcyclopentadienyl)benzene and p-Ph’: p-Bis(2,3,4,5-tetramethylcyclopentadienyl)benzene), were compared with the catalytic activity of the catocene (cat) complex previously reported. Furthermore, in order to clarify the mechanism of the bimetallic compounds, it was tested ferrocene (Fc), frequently used as burning rate (BR) catalyst on the thermal decomposition of AP. The synthetized compounds shown a shift on the peak temperature to lower values and an increase in the released heats during thermal decomposition of AP. The burning rate catalytic activity of the compounds on thermal decomposition of AP were examined by thermogravimetry and differential scanning calorimetry techniques. Theoretical calculations of these compounds were carried out to gain further understanding of these catalysts systems.

Ionic Ferrocenyl Coordination Compounds Derived from Imidazole and 1,2,4‐Triazole Ligands and Their Catalytic Effects During Combustion

Alkylferrocene‐based burning‐rate catalysts (BRCs) show conspicuous migration tendency and volatility during prolonged storage and fabrication process of a composite solid propellant. To enhance anti‐migration ability of the BRCs, forty novel ionic coordination compounds, [M(L)4(H2O)2]mXn (M = Mn2+, Co2+, Cu2+, Ni2+, Zn2+, Fe2+, Pb2+, Cr3+, Bi3+, or Cd2+; L = ferrocenylmethyl imidazole or ferrocenylmethyl‐1,2,4‐triazole; X = picrate or trinitroresorcinolate), were synthesized and characterized by FT‐IR, UV/Vis, and elementary analysis. Additionally, the crystal structures of six compounds were confirmed by single‐crystal X‐ray diffraction. The TG analyses revealed that the new compounds show high thermal stability. Cyclic voltammetry studies suggested that theyare irreversible redox systems. Their catalytic activities in the thermal degradation of ammonium perchlorate (AP), 1,3,5‐trinitro‐1,3,5‐triazacyclo‐hexane (RDX) and 1,2,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX) were examined by DSC technique. The results indicated that all the new compounds exert great effects on the thermal decomposition of AP and RDX, among them some compounds are more active than catocene. Compound 26 has good catalytic ability in the thermal decomposition of HMX, representing a rare example of the reported ferrocene‐based BRCs which show catalytic activity during combustion of HMX.

Tris(2‐aminoethyl)amine‐based ferrocene‐terminated dendrimers as burning rate catalysts for ammonium perchlorate‐based propellant decomposition

Ferrocene‐based derivatives show potential application as burning rate catalysts (BRCs) for solid composite propellants. However, migration problems of simple ferrocene‐based derivatives limit their application as BRCs in solid composite propellants. To overcome the migration problems of ferrocene‐based BRCs and to enhance the burning rate of ammonium perchlorate (AP)‐based propellants, zero‐ to second‐generation tris(2‐aminoethyl)amine‐based ferrocene‐terminated dendrimers (G0, G1 and G2) were synthesized. The structures of G0, G1 and G2 were confirmed using 1H NMR, Fourier transform infrared and UV–visible spectroscopies. The electrochemical behavior of G0, G1 and G2 was investigated using cyclic voltammetry. It was found that G0, G1 and G2 showed redox behavior due to the presence of ferrocene and this redox behavior was diffusion controlled over the investigated scan range. The burning rate catalytic effect of G0, G1 and G2 on thermal decomposition of AP was investigated using thermogravimetry and differential thermogravimetry. G0, G1 and G2 showed good catalytic effect on the thermal decomposition of AP. Anti‐migration studies showed that migration of G0, G1 and G2 was much slower than that of 2,2‐bis(ethylferrocenyl)propane (catocene) and ferrocene.

Energetic Nanocomposites as Burn Rate Catalyst for Composite Solid Propellants

AbstractIn the present study the effect of addition of Al/Fe2O3 based energetic nanocomposites (ENC) to non‐aluminized and aluminized propellants was investigated. Comparative study was carried out using n‐Fe2O3 as burn rate catalyst. Ferric oxide xerogel and Al/Fe2O3 ENC were synthesized by sol‐gel method. The dried xerogel was characterised by Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). TEM and SEM images reveal presence of porous interconnected ferric oxide clusters of size 3–5 nm and intimate mixing of the ingredients at nanoscale in case of ENC. XRD analysis shows amorphous nature of the ferric oxide xerogel. Fe2O3 and FeO(OH) are the major constituents (>84 %) of the xerogel as confirmed by XPS analysis. Thermal analysis of the ENC indicates that the composition is energetic in nature. Sensitivity analysis was carried out to assess the safety of the ENC during propellant processing. The differential scanning calorimetry (DSC) results for propellant samples show that the Al/Fe2O3 ENC is a better catalyst for AP decomposition than n−Fe2O3. Burn rate studies of ENC catalyzed propellants with μ‐Al and with n‐Al were carried out using acoustic strand burner. The results indicate that ENCs can be promising catalysts for composite propellants.

Synthesis of ferrocene‐modified poly(glycidyl methacrylate) and its burning rate catalytic property

A series of ferrocene‐modified poly(glycidyl methacrylate) (PGMA‐Fc) compounds were synthesized and applied as burning rate catalysts in simulative solid propellant to overcome migration problems. 1H NMR and Fourier transform infrared spectroscopies and gel permeation chromatography were used to characterize the synthesized polymers. Their electrochemical behavior was evaluated using cyclic voltammetry. Their catalytic performance for the decomposition of ammonium perchlorate (AP) was investigated using thermogravimetric analysis. Anti‐migration studies were conducted in migration tubes under 50°C. The results show that PGMA‐Fc has a good catalytic effect on lowering the thermal decomposition temperature of AP. Anti‐migration studies show that PGMA‐Fc has better anti‐migration performance than ferrocene and catocene.