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1.
Four different samples of ferrocene‐grafted hydroxyl‐terminated polybutadiene (Fc‐HTPB), containing 0.20, 0.52, 0.90, and 1.50 wt % iron, were synthesized by the Friedel–Crafts alkylation of ferrocene with hydroxyl‐terminated polybutadiene (HTPB) in the presence of AlCl3 as a (Lewis acid) catalyst. The effects of the reaction conditions on the extent of ferrocene substitution were investigated. The Fc‐HTPBs were characterized by IR, ultraviolet–visible, 1H‐NMR, and 13C‐NMR spectra. The iron content and number of hydroxyl groups were estimated, and the properties, including thermal degradation, viscosity, and propellant burning rates (BRs), were also studied. The thermogravimetric data indicated two major weight loss stages around 395 and 500°C. These two weight losses were due to the depolymerization and decomposition of the cyclized product, respectively, with increasing temperature. The Fc‐HTPB was cured with toluene diisocyanate and isophorone diisocyanate separately with butanediol–trimethylolpropane crosslinker to study their mechanical properties. Better mechanical properties were obtained for the gumstock of Fc‐HTPB polyurethanes with higher NCO/OH ratios. The BRs of the ammonium perchlorate (AP)‐based propellant compositions having these Fc‐HTPBs (without dilution) as a binder were much higher (8.66 mm/s) than those achieved with the HTPB/AP propellant (5.4 mm/s). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

2.
We observed that modified polyphenylene ether (PPE) was solubilized in thermoplastic styrenic elastomer (TPS) and that a two‐phase lacy structure formed on nanometer scales when the TPS composition was 67 wt % and modified PPE and polystyrene‐block‐poly(styrene‐co‐ethylene‐co‐butylene)‐block‐polystyrene (S‐SEB‐S triblock copolymer) were blended. However, the molecular weight of the outer PS block segments MoutPS and the content of the outer PS block segments ?outPS were <10,000 g/mol and 20 wt %, respectively. The resulting S‐SEB‐S/modified PPE nano‐alloy exhibited both flexibility and flame retardancy, unlike other materials, where a trade‐off exists between these two properties; that is, the flame retardancy was excellent when the phosphorus additive was present. This combination of properties might be attributed to the two‐phase nanometer‐scale structure consisting of flame‐retardant styrene/PPE domains and a continuous soft, lacy SEB matrix. The results for polystyrene‐block‐poly(ethylene‐co‐butylene)‐block‐polystyrene (S‐EB‐S triblock copolymer)/modified PPE blends were presented for comparison. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40446.  相似文献   

3.
This paper presents an overview of a modified composite propellant formulation to meet future requirements. The composite propellant mixtures were prepared using nitro functionalized Hydroxyl‐Terminated Polybutadiene (Nitro‐HTPB) as a novel energetic binder and addition of energetic plasticizer. The new propellant formulation was characterized and tested. It was found that the Nitro‐HTPB propellant with and without energetic plasticizer exhibited high solid loading, high density, and reasonable mechanical properties over a wide range of temperatures. It was shown that the burning rate of Nitro‐HTPB propellant is up to 40% faster than that of the HTPB propellant. These results are encouraging and suggest that it should be possible to improve the ballistic performance of popular HTPB propellants through use of the studied Nitro‐HTPB binder.  相似文献   

4.
A series of symmetrical triblock copolymers containing crystallizable high-trans-1,4-polybutadiene (HTPB) were synthesized by sequential anionic polymerization of 1,3-butadiene (Bd) with isoprene (Ip) (or styrene (St)) using barium salt of di(ethylene glycol) ethyl ether/triisobutylaluminium/dilithium (BaDEGEE/TIBA/DLi) as initiation system. The microstructures of the symmetrical triblock copolymers were determined by IR, 1H NMR, and 13C NMR. The results indicated that polyisoprene-block-high-trans-1,4-polybutadiene-block-polyisoprene (IBI) contained HTPB segments and medium 3,4-polyisoprene (PI) segments, and polystyrene-block-HTPB-block-polystrene (SBS) contained HTPB and atatic-polystyrene (PS) segments. The DSC analysis revealed that SBS tended to phase separate but IBI did not. The cold crystallization was observed in IBI but not in SBS.  相似文献   

5.
Polytetrahydrofuran (PTHF) is an effective binder ingredient for improving propellant performance, even though it is not an energetic material. PTHF becomes sufficiently rubbery for use as a binder when a triol material such as glycerin is added as a crosslinking modifier. The cured PTHF/glycerin binder had unsatisfactory mechanical characteristics for use as a propellant binder, so a more appropriate crosslinking modifier than glycerin needs to be found. In this study, glycerol propoxylate (GPO), with a molecular weight of 260, was used as a crosslinking modifier, and the curing behavior, tensile properties, and thermal decomposition behaviors of the PTHF binder using GPO were investigated. The PTHF/GPO blend did not solidify when the PTHF/GPO mole ratio (ξ) was greater than a certain value. The PTHF (Mn=650)/GPO blend with ξ≤5 and the PTHF (Mn=1400)/GPO blend with ξ≤3 were used as propellant binders. From the curing behaviors and tensile properties, it was found that the PTHF/GPO binders ensured optimal mixing of the propellant ingredients and casting of the uncured propellant into the rocket motor case, and the tensile properties of the binders changed more drastically with the variation in ξ than did those of the PTHF/glycerin binders. The thermal decomposition behaviors of the PTHF/GPO binders were hardly dependent on ξ and were almost identical to those of the PTHF/glycerin binders.  相似文献   

6.
Solid composite propellants contain 80–90% of a crystalline oxidizer like ammonium perchlorate and powdery metallic fuel like aluminum with 10 to 15% organic binders like HTPB or CTPB, to bind the solids together and maintain the shape under severe stress and strain environment. Also, the propellant must not crack or become brittle at subzero temperatures. Formulating and processing of the highly filled composite propellants are difficult tasks and need a thorough understanding of rheology, even apart from a knowledge of propellant chemistry, particulate technology, manufacturing methods, and safe handling of explosives and hazardous materials. The flow behavior or rheology of the propellant slurry determines the ingredients and some of the abnormalities of the motor during firing. The propellant viscosity and mechanical properties are determined by the binder system, and the unloading viscosity of the propellant slurry is dependent on the initial viscosity of the binder system, solid loading, particle size, and its distribution, shape, temperature, and pressure. In the present report an attempt is made to study the dependency of viscosity of the HTPB binder system on temperature, plasticizer level (composition), and torque (angular velocity of spindle). The viscosity measurements were made using a Brookfield viscometer model DV III at different plasticizer levels (10–50%), temperatures (30–65°C), and torques (50–100%). The data indicate that the viscosity of HTPB, DOA, and their mixture decreases with increasing temperature and is constant with torque. The Arrhenius equation gives the energy for viscous flow to be ?35 kcal/mol for HTPB. The variation of viscosity with temperature of HTPB/DOA and their mixture follows a mathematical model expressed as where T is the temperature and a1, a2, a3, a4, and a5 are the constants. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1002–1007, 2002  相似文献   

7.
Due to the requirements for the preparation of an ammonium perchlorate (AP)/hydroxy‐terminated polybutadiene (HTPB) based composite propellant, an upper limit content of AP applicable in the propellant, φmax (wt%), exists. The rheology of concentrated AP/HTPB suspensions prepared at φmax is investigated in this study. The relative viscosity, η(‐), of the suspensions prepared at φmax is almost constant at approximately 200. For the suspensions prepared at φmax, the HTPB layer thickness, Hφp (µm), on the AP particle, calculated from the specific surface area measured by the air‐permeability method, is closely related to the void fraction, εmax(‐), for the loose packing of the AP powder. Hφp decreases with increasing εmax. By reversal conclusion it was found that the relative viscosity of the suspension, of which the HTPB layer thickness is Hφp, will accordingly be η.  相似文献   

8.
In previous papers, the synthesis and characterization of OH‐terminated glycidyl azide‐r‐(3,3‐bis(azidomethyl)oxetane) copolymers (GA/BAMO) and poly‐3‐azidomethyl‐3‐methyl oxetane (pAMMO) by azidation of their respective polymeric substrates were described. The main objective was the preparation of amorphous azido‐polymers, as substitutes of hydroxy‐terminated polybutadiene (HTPB) in new formulations of energetic propellants. Here, the subsequent characterization of both the binders is presented. First of all, several isocyanates were checked in order to optimize the curing reaction, and then two small‐scale formulations of a propellant, based on aluminium and ammonium perchlorate, were prepared and characterized. Finally, the mechanical properties and burning rate were compared to those of a similar propellant based on HTPB as binder.  相似文献   

9.
Amorphous boron powder granulated with HTPB, whose particle diameter could be controlled, was prepared by mechanical mill method. It was found that amorphous boron powder could be granulated with HTPB binder to form B‐HTPB particles, whose median particle diameter (d50) and specific surface area are in the range of 125.0–431.0 µm and 0.02–0.1 m2 g−1, respectively. The B‐HTPB particles could be dispersed in the HTPB binder with relatively low viscosity compared with direct addition of amorphous boron powder to the HTPB binder. The experimental results showed that the content of boron particles in a fuel‐rich propellant could be increased by addition of B‐HTPB particles and the combustion characteristics of the fuel‐rich solid propellant could be improved.  相似文献   

10.
利用国军标方法及CAD系统软件,在标准条件(pc∶p0=70∶1)下,计算了含1,1-二氨基-2,2-二硝基乙烯(FOX-7)的各类推进剂的能量特性参数,分析了氧化剂(AP、RDX、CL-20)及黏合剂(HTPB、PET、GAP、PBAMO)等成分对FOX-7推进剂能量特性的影响。结果表明,将AP加入HTPB/FOX-7推进剂配方中取代FOX-7可有效改善氧条件,有利于推进剂能量的提高。在黏合剂含量较低(质量分数<8%)的推进剂体系中,使用惰性黏合剂有利于提高推进剂的能量;而在黏合剂含量较高(质量分数>10%)的推进剂体系中,使用含能黏合剂提高推进剂能量的幅度优于惰性黏合剂,且GAP优于PBAMO。用FOX-7取代NEPE推进剂中的AP,推进剂最大理论比冲可达2 567 N.s/kg。由GAP/FOX-7/RDX组成的无烟推进剂,在很宽的范围内都可以达到2 400 N.s/kg以上的理论比冲值。  相似文献   

11.
Hydroxyl terminated polybutadiene (HTPB) is widely used as a propellant binder. A plasticizer is usually added to improve the processing properties, the mechanical properties, and the burning characteristics of the propellant. Glycerin was found to be an effective additive to improve these properties. The glycerin/HTPB blend was hard enough to act as a binder for the composite propellant when the glycerin/HTPB mole ratio was less than 10. Only a small quantity of glycerin was incorporated into the network structure of the cured HTPB. Most of the added glycerin physically entered the voids in the network of the cured HTPB. Addition of a small quantity of glycerin (mole ratio less than 0.1) significantly altered the network density and the viscoelastic properties of the blends. The properties were only slightly dependent on the amount of the added glycerin in the mole ratio range of 0.1–10. The dangling ends were formed in the HTPB network by the addition of glycerin and the network structure was loosened, thereby enhancing the mobility of the chain segment. The viscoelastic properties of the blends followed the time‐temperature superposition principle, and the properties were estimated accurately by the Williams‐Landel‐Ferry approach. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

12.
An effective pathway was explored to design and select proper bonding agents that could effectively improve the interfacial interactions between bonding agents and solid particles, with three novel synthesized alkyl bonding agents, dodecylamine‐N,N‐di‐2‐hydroxypropyl‐acetate (DIHPA), dodecylamine‐N,N‐di‐2‐hydroxypropyl‐hydroxy‐acetate (DIHPHA) and dodecylamine‐N,N‐di‐2‐hydroxypropyl‐cyano‐acetate (DIHPCA), as examples. Molecular dynamics simulation was applied to compare unit bond energies of these bonding agents with the [110] crystal face of ammonium perchlorate (AP) and the [120] crystal face of hexogen (RDX). The infrared test was used to characterize the interfacial interactions of these bonding agents with AP or RDX. XPS test was applied to calculate the adhesion percentage of the bonding agents on the surface of precoated AP or RDX particles. All of the above results indicated that these three bonding agents have strong interfacial interactions with AP or RDX in the order of DIHPCA>DIHPHA>DIHPA. The prepared three bonding agents were used in HTPB/AP/RDX/Al propellants, and their effects on tensile strength (σ), elongation under maximum tensile strength (εm), elongation at breaking point of the propellant (εb) and adhesion index (Φ) of the propellant were studied. The results show that the bonding agents improve the mechanical properties of the propellant in the order of DIHPCA>DIHPHA>DIHPA. The methods found from theoretical design, materials synthesis, and mechanistics studies up to practical application show effective guiding significance for choosing the proper bonding agent and improving the interfacial interactions between the solid particles and binder matrix.  相似文献   

13.
The aim of this study was to evaluate the role of different poly(ethylene glycol):poly(propylene glycol) (PEG:PPG) molar ratios in a triblock copolymer in the cure kinetics, miscibility and thermal and mechanical properties in an epoxy matrix. The poly(propylene glycol)‐block‐poly(ethylene glycol)‐block‐poly(propylene glycol) (PPG‐b‐PEG‐b‐PPG) triblock copolymers used had two different molecular masses: 3300 and 2000 g mol?1. The mass concentration of PEG in the copolymer structure played a key role in the miscibility and cure kinetics of the blend as well as in the thermal–mechanical properties. Phase separation was observed only for blends formed with the 3300 g mol?1 triblock copolymer at 20 wt%. Concerning thermal properties, the miscibility of the copolymer in the epoxy matrix reduced the Tg value by 13 °C, although a 62% increase in fracture toughness (KIC) was observed. After the addition of PPG‐b‐PEG‐b‐PPG with 3300 g mol?1 there was a reduction in the modulus of elasticity by 8% compared to the neat matrix; no significant changes were observed in Tg values for the immiscible system. The use of PPG‐b‐PEG‐b‐PPG with 2000 g mol?1 reduced the modulus of elasticity by approximately 47% and increased toughness (KIC) up to 43%. Finally, for the curing kinetics of all materials, the incorporation of the triblock copolymer PPG‐b‐PEG‐b‐PPG delayed the cure reaction of the DGEBA/DDM (DGEBA, diglycidyl ether of bisphenol A; DDM, Q3‐4,4′‐Diaminodiphenylmethane) system when there is miscibility and accelerated the cure reaction when it is immiscible. All experimental curing reactions could be fitted to the Kamal autocatalytic model presenting an excellent agreement with experimental data. This model was able to capture some interesting features of the addition of triblock copolymers in an epoxy resin. © 2018 Society of Chemical Industry  相似文献   

14.
Polytetrahydrofuran (PTHF) is an effective binder ingredient for improving propellant performance, although it is not an energetic material. PTHF becomes sufficiently rubbery for use as a binder when a triol is added as a crosslinking modifier. In this study, glycerol propoxylate (GPO), with a molecular weight of 1500, was used as a crosslinking modifier, and the curing behavior, tensile properties, and thermal decomposition behaviors of the PTHF binder with GPO were investigated. A PTHF (M n=650)/GPO blend with a PTHF/GPO mole ratio (ξ ) less than or equal to 4 and a PTHF (M n=1400)/GPO blend with ξ ≤1 were used as propellant binders. The curing behaviors and mechanical properties of the PTHF/GPO blends were influenced by the molecular weight of PTHF and ξ , while the thermal decomposition behaviors were not affected. It was found that the PTHF/GPO blends had higher initial viscosity, longer pot life, and unique mechanical properties compared to those of the PTHF blends supplemented with GPO (M n=260).  相似文献   

15.
The nitration of low molecular weight polybutadiene (PB) by a convenient and inexpensive procedure was investigated. To retain the unique physico‐chemical properties of the plasticizer, it was nitrated to an extent of 10 % double bonds. The product nitropolybutadiene (NPB) was characterized by FT‐IR and 1H NMR spectroscopy as well as GPC, DSC, and TGA methods. The kinetic parameters for the decomposition of NPB from room temperature to 400 °C were obtained from non‐isothermal DSC. The changes in glass transition temperature (T g) and inert uncured binder systems were used for determination of its efficiency as plasticizer. NPB was used in cured and unfilled nitro‐hydroxyl terminated polybutadiene (NHTPB) binder. Isothermal thermogravimetric analysis (Iso‐TGA) was employed to determine the migration rate in cured and unfilled HTPB binder systems compared to the dioctyladiphate (DOA) plasticizer. It was found that the exudation of the NPB plasticizer is slower than that of the DOA plasticizer. Thus, the NHTPB/NPB binder system (binder/plasticizer) presents more convenient mechanical properties than HTPB/DOA and is a promising new energetic binder system for polymer bonded explosives.  相似文献   

16.
The burning rate of AP/HTPB composite propellant increases with increasing AP content and with decreasing AP size. In addition, the burning rate can be enhanced with the addition of Fe2O3. The burning characteristics and thermal decomposition behavior of AP/HTPB composite propellant using coarse and fine AP particles with and without Fe2O3 at various AP contents were investigated to obtain an exhaustive set of data. As the AP content decreased, the burning rate decreased and the propellants containing less than a certain AP content self‐quenched or did not ignite. The self‐quenched combustion began at both lower and higher pressures. The lower limit of AP content to burn the propellant with coarse AP was lower than that with fine AP. The lower limit of AP content to burn was decreased by the addition of Fe2O3. The thermal decomposition behavior of propellants prepared with 20–80 % AP was investigated. The decrease in the peak temperature of the exothermic decomposition suggested an increased burning rate. However, a quantitative relationship between the thermochemical behavior and the burning characteristics, such as the burning rate and the lower limit of AP content to burn, could not be determined.  相似文献   

17.
We report the functionalization of hydroxyl terminated polybutadiene (HTPB) backbone by covalently attaching 1‐chloro‐2, 4‐dinitrobenzene (DNCB) at the terminal carbon atoms of the HTPB. The modification of the HTPB by the DNCB does not alter the unique physico–chemical properties and the microstructure of the parent HTPB. IR, 1H‐NMR, 13C‐NMR, size exclusion chromatography (SEC) and absorption spectroscopy studies prove that the DNCB molecules are covalently attached to the terminal carbon atoms of the HTPB. The π electron delocalization owing to long polymer chain, strong electron withdrawing effect of the DNCB molecule are the major driving forces for the covalent attachment of the DNCB at the terminal carbon atom of the HTPB. We are the first to observe the existence of intermolecular hydrogen bonding between the terminal hydroxyl groups of the HTPB. IR study shows that the attached DNCB molecules at the terminal carbon atoms of the HTPB breaks the intermolecular hydrogen bonding between the HTPB chains and forms a hydrogen bonding between the NO2 groups of the DNCB and the OH groups of the HTPB. Absorption spectral study of the modified HTPB indicates the better delocalization of π electron of butadiene due to the strong electron withdrawing effect of the DNCB molecules. Theoretical calculation also supports the existence of hydrogen bonding between the OH and NO2 groups. Theoretical calculation shows that the detonation performance of both the DNCB and the HTPB‐DNCB are promising. HTPB‐DNCB is the new generation energetic binder which has potential to replace the use of HTPB as binder for propellant.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

18.
The triblock energetic copolymer poly(lactic acid)‐block‐(glycidylazide polymer)‐block‐polystyrene (PLA‐b‐GAP‐b‐PS) was synthesized successfully through atom‐transfer radical polymerization (ATRP) of styrene and ring‐opening polymerization of d,l ‐lactide. The energetic macroinitiator GAP‐Br, which was made from reacting equimolar GAP with α‐bromoisobutyryl bromide, firstly triggered the ATRP of styrene with its bromide group, and then the hydroxyl group on the GAP end of the resulting diblock copolymer participated in the polymerization of lactide in the presence of stannous octoate. The triblock copolymer PLA‐b‐GAP‐b‐PS had a narrow distribution of molecular weight. In the copolymer, the PS block was solvophilic in toluene and improved the stability of the structure, the PLA block was solvophobic in toluene and served as the sacrificial component for the preparation of porous materials, and GAP was the basic and energetic material. The three blocks of the copolymer were fundamentally thermodynamically immiscible, which led to the self‐assembly of the block copolymer in solution. Further studies showed that the concentration and solubility of the copolymer and the polarity of the solvent affected the morphology and size of the micelles generated from the self‐assembly of PLA‐b‐GAP‐b‐PS. The micelles generated in organic solvents at 10 mg mL?1 copolymer concentration were spherical but became irregular when water was used as a co‐solvent. The spherical micelles self‐assembled in toluene had three distinct layers, with the diameter of the micelles increasing from 60 to 250 nm as the concentration of the copolymer increased from 5 to 15 mg L?1. © 2017 Society of Chemical Industry  相似文献   

19.
A hydroxy‐terminated polybutadiene (HTPB)/isophorone diisocyanate (IPDI) elastomer is commonly used as propellant binder material. The thermal degradation of the binder is believed to be an important parameter governing the performance of the propellant. The aging of these binders can be monitored by mechanical property measurements, such as modulus or tensile elongation. These techniques, however, are not easily adapted to binder agents that are dispersed throughout a propellant. In this paper we investigated solid‐state nuclear magnetic resonance (NMR) relaxation times as a means to predict the mechanical properties of the binder as a function of aging time. Proton (1H) spin–lattice and spin–spin relaxation times were insensitive to the degree of thermal degradation of the elastomer. Apparently, these relaxation times depend on localized motions that are only weakly correlated with mechanical properties. A strong correlation was found between the 13C cross‐polarization (CP) NMR time constant, Tcp, and the tensile elongation at break of the elastomer as a function of aging time. A ramped‐amplitude CP experiment was less sensitive to imperfections in setting critical instrumental parameters for this mobile material. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 453–459, 2001  相似文献   

20.
BuNENA含能增塑剂的性能及应用   总被引:3,自引:0,他引:3  
BuNENA(N–丁基硝氧乙基硝胺)是一种性能优良的新型含能增塑剂,在枪炮发射药和火箭推进剂应用中均受到研究者的广泛关注,并被进行系统研究。在发射药中,BuNENA具有塑化能力强、工艺性能好、感度低、能量高等优点,能进一步提高配方力学性能,其应用前景广阔。而在HTPE(端羟基聚环氧乙烷–四氢呋喃嵌段共聚醚)火箭推进剂中,BuNENA已被证明是一种对提高能量、降低感度和提高推进剂力学性能等具有明显作用的新型含能增塑剂,使用HTPE/BuNENA黏合剂体系的钝感固体推进剂的综合性能优于HTPB/AP(端羟基聚丁二烯/高氯酸铵)推进剂,并可满足钝感弹药(IM)要求,已在各种战术发动机中获得了实际应用。  相似文献   

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