Curing characteristics of glycidyl azide polymer‐based binders

The curing of a glycidyl azide polymer (GAP) with a triisocyanate, Desmodur N‐100, was followed by measuring the hardness and viscosity. The thermal behavior of the cured samples were investigated by a differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA). Curing causes an increase in the glass transition temperature of GAP. The T_g of gumstocks also increases with an increasing NCO/OH ratio while the decomposition temperature remains practically unchanged. The ultimate hardness of the cured samples increases with an increasing NCO/OH ratio. The binder with a NCO/OH ratio of 0.8 was found to provide the most suitable thermal and physical characteristics for composite propellant applications. The increase in the glass transition temperature of gumstocks upon curing can be compensated by using a 1:1 mixture of bis‐2,2‐dinitropropyl acetal and formal as the plasticizer. The T_g value of gumstocks can be decreased to −46.7°C by adding 25% b.w. of a plasticizer which does not have any significant effect on the decomposition properties of the gumstocks. Furthermore, a remarkable decrease in the ultimate hardness of the gumstocks is achieved upon addition of a plasticizer, while the curing time remains almost unaffected. The addition of dibuthyltin dilaurate as a catalyst reduces the curing time of the gumstocks from 3 weeks to 5–6 days at 60°C. Use of the curing catalyst also results in the hardening of the gumstocks. The decomposition properties of the gumstocks remain practically unchanged while a noticeable increase is observed in the glass transition temperature with an increasing concentration of the catalyst. This can also be compensated by a reverse effect of the plasticizer. The gel time, an important parameter which determines the pot life of a propellant material, can be measured by monitoring the viscosity of the mixture, which shows a sharp increase when gelation starts. The addition of a curing catalyst shortens the gel time remarkably. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 65–70, 2001     

Molecular-beam mass-spectrometric study of the flame structure of composite propellants based on nitramines and glycidyl azide polymer at a pressure of 1 MPa

A study was performed of the chemical and thermal structure of flames of model composite propellants based on cyclic nitramines (RDX and HMX) and an active binder (glycidyl azide polymer) at a pressure of 1 MPa. Propellant burning rates were measured. The chemical structure of the flame was studied using molecular-beam mass spectrometry, which previously has not been employed at high pressures. Eleven species (H₂, H₂O, HCN, N₂, CO, CH₂O, NO, N₂O, CO₂, NO₂, and nitramine vapor) were identified, and their concentration profiles, including the composition near the burning surface were measured. Two chemical-reaction zones were observed. It was shown that flames of nitramine/glycidyl azide polymer propellants are dominated by the same reactions as in flames of pure nitramines. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 48–57, November–December, 2006.     

Core–shell type multi‐arm azide polymers based on hyperbranched copolyether as potential energetic materials in solid propellants

A series of novel multi‐arm azide copolymers (POGs) with the same hyperbranched poly[3‐ethyl‐3‐(hydroxymethyl)oxetane] core (PEHO‐c) and different content of linear glycidyl azide polymer shell (GAP‐s) have been synthesized by sequential cationic ring‐opening polymerization and azidation. Detailed structural information of these copolyethers was deduced from Fourier transform infrared, ¹H NMR and inverse gated decoupled ¹³C NMR spectroscopies, matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry, gel permeation chromatography and elemental analysis. The molecular weight of POG having GAP‐s and PEHO‐c with a molar ratio 14.95:1 (R_s/c) was around 31 000 g mol^?1, far above that of linear GAP (around 4000 g mol^?1). The apparent viscosity and glass transition temperature (?51 to ?23 °C) decreased first and then slightly increased with increasing molecular weight. Thermal analysis revealed that all the obtained POGs exhibited excellent resistance to thermal decomposition up to 220 °C. Moreover, the energetic properties, investigated using oxygen bomb calorimetric measurements, indicated that the enthalpy of formation of the POGs was higher than that of general linear GAP, but similar to that of branched GAP under reasonable R_s/c. The compatibilities of the POGs with common materials used in solid propellants were studied using differential scanning calorimetry and the results indicated that the POGs had good compatibility with these materials. © 2017 Society of Chemical Industry     

Thermal structural damage and thermal decomposition characterization of GAP propellants with nitrate ester plasticizers

GAP and nitrate ester compounds are introduced into the solid propellant formulation as energetic binders and energetic plasticizing agents, respectively, to further enhance the energy level of solid propellants. However, under abnormal thermal conditions, various components within GAP propellants, especially nitrate ester plasticizers, can collectively result in the generation of a large number of voids within the propellant due to factors such as thermal stress and slow component decomposition. This phenomenon can impact the safety of solid rocket engines, necessitating research into their thermal decomposition processes and thermal damage structures. In this study, the thermal decomposition characteristics and gas products of GAP propellants with different nitrate ester plasticizer formulations were investigated using DSC-TG and FT-IR. The damage structure of GAP propellants heated under unignited conditions was studied through Micro-CT, examining the influence of heating conditions and nitrate ester plasticizers on the thermal damage structure of GAP propellants. During heating, the thermal damage structure of GAP propellants was found to include voids generated within the GAP binder and cracks at the interface between the GAP binder and particles, with nitroglycerin as a plasticizer exacerbating the thermal damage of GAP propellants (about 2.2–2.9 times).     

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

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

GAP黏合剂胶片力学性能的影响因素

应用静态拉伸、动态力学和核磁交联密度仪等方法研究了增塑剂正丁基硝氧乙基硝胺(BuNENA)、固化剂多异氰酸酯(N-100)和甲苯二异氰酸酯(TDI)、交联剂三羟甲基丙烷(TMP)、扩链剂1,4-丁二醇(BDO)对改性聚叠氮缩水甘油醚(GAP)黏合剂胶片力学性能的影响。结果表明,增塑比(Pl/Po)由0.6增至1.6,GAP黏合剂胶片的拉伸强度由0.22MPa降至0.06MPa,交联密度由6.7×10-5 mol/mL降至4.9×10-5 mol/mL,延伸率略有提升。调节N-100/TDI双固化体系,可提高GAP黏合剂胶片的强度和延伸率,当N-100和TDI的固化参数分别为0.36、1.44时,胶片强度和延伸率分别为0.24MPa和558.7%。加入质量分数0.5%的交联剂TMP可使GAP黏合剂胶片强度升至0.32MPa,延伸率降至278.5%。加入质量分数0.1%的扩链剂BDO,可使胶片强度和延伸率分别达到0.33MPa和323.1%。     

Kinetics of polyurethane formation between glycidyl azide polymer and a triisocyanate

Kinetics of the polyurethane formation between glycidyl azide polymer (GAP) and a polyisocyanate, Desmodur N‐100, were studied in the bulk state by using quantitative FTIR spectroscopy. The reaction was followed by monitoring the change in intensity of the absorption band at 2270 cm^?1 for NCO stretching in the IR spectrum, and was shown to obey second‐order kinetics up to 50% conversion. The activation parameters were obtained from the evaluation of kinetic data at different temperatures in the range of 50–80°C. The enthalpy and entropy of activation were found to be ΔH^? = 44.1 ± 0.5 kJ · mol^?1 and ΔS^? = ?196 ± 2 J · mol^?1l · K^?1, respectively. Dibutyltin dilaurate (DBTDL) was used as the curing catalyst. The kinetic study of the polyurethane formation between GAP and Desmodur N‐100 showed that the reaction is enormously speeded up in the presence of the catalyst, and the reaction obeys second‐order kinetics, provided that the catalyst concentration is kept constant. An investigation on the rate of the catalysed reaction depending on the catalyst concentration provided the order of the reaction, with respect to the DBTDL catalyst concentration, and the rate constant for the catalytic pathway of the reaction. The rate constant for the catalytic pathway was established to be 4.37 at 60°C, while the uncatalyzed reaction has a rate constant of 3.88 × 10^?6 L · mol^?1 · s^?1 at the same temperature. A rate enhancement factor of 23 was achieved by using 50 ppm catalyst. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 918–923, 2001     

GAP高能低特征信号推进剂的燃烧性能调节

研究了硝胺种类、固体组分含量和粒度、增塑剂与GAP的增塑比及燃速催化剂对GAP高能低特征信号推进剂在11~19MPa下燃烧性能的影响。结果表明,当HMX取代推进剂样品中的RDX时,推进剂的燃速较高,压强指数从0.72降至0.63;在AP和HMX总质量分数为67.5%的条件下,随着AP质量分数由5%增至30%,推进剂燃速逐渐增大,压强指数由0.82降至0.45;减小AP粒度以及在配方中添加燃速催化剂或调节过渡金属化合物J1/J2的配比,可较大幅度地增加推进剂燃速和降低压强指数,其中,J1与J2总质量分数为3%,二者质量比为2∶1和1∶1时,推进剂的压强指数较小,分别为0.50和0.48;随着HMX粒度减小及增塑剂与GAP黏合剂的增塑比的降低,推进剂的燃速和压强指数降低。     

Rheological and thermal properties of glycidyl azide polyol‐based energetic thermoplastic polyurethane elastomers

The purpose of this study was to investigate the effects of polyol on glycidyl azide polyol (GAP)‐based energetic thermoplastic polyurethane elastomers (ETPEs). Briefly, a series of GAP/polyol‐based ETPEs (GAP/polyol ETPEs) with different copolyol ratios and hard segment contents were synthesized using GAP‐diol with common polyol and 4,4‐methylenebis(phenylisocyanate)‐extended 1,5‐pentanediol as soft and hard segments, respectively, by solution polymerization in dimethylformamide. The three types of polyols used were poly(tetramethylene ether) glycol (PTMG), polycarbonate‐diol (PCL‐diol) and polycaprolactone‐diol (PCD‐diol). The synthesized GAP/polyol ETPEs were identified and characterized using Fourier transform infrared and ¹H NMR spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and rheometric mechanical spectrometry. For GAP/PCL ETPEs with lower hard segment content, DSC results showed that the GAP segment failed to interact with either the PCL segment or PCL melting. In addition, the results of DMA showed that the presence of PCL segments in ETPEs improved the storage modulus below the melting temperature of the PCL block. Further, the crystalline PCL segments were attributed to reinforcing the ETPEs in a manner similar to that of the hard domain. As the hard segment content increased in the GAP/polyol ETPEs, both GAP/PTMG ETPEs and GAP/PCL ETPEs exhibited microphase separation transitions, while rheological experiments demonstrated a sudden decrease in complex viscosity in neighboring microphase separation transitions. © 2012 Society of Chemical Industry     

聚叠氮缩水甘油醚的合成与改性研究进展

聚叠氮缩水甘油醚(GAP)是国内外重点研究的含能粘合剂之一。该文综述了GAP的合成研究进展,重点介绍了高相对分子质量GAP、支化GAP和等规GAP的合成。针对GAP反应活性低的特点,介绍了GAP的多种端基改性方法。GAP的无规、嵌段共聚物改善了GAP粘合剂的性能,GAP与其他粘合剂的互穿及共混,为GAP在推进剂中的应用提供了广阔前景。引用文献37篇。     

GAP型交联改性双基推进剂黏合剂的力学性能

将GAP与异氰酸酯预聚后引入双基推进剂黏合剂中,研究了固化剂种类、R值、固化催化剂二月桂酸二丁基锡(T12)的含量和增塑比对黏合剂的交联网络结构参数RNB值和力学性能的影响。结果表明,随着R值以及(T12)含量的增大,黏合剂的RNB值增大。在与NC中活性-OH交联反应时,TDI的反应活性比IPDI的高。GAP-TDI/NC/NG胶片的最大抗拉强度和断裂延伸率分别可达1.09MPa和202.12%,Tg最低为-42.66℃。     

Synthesis of poly(methyl methacrylate‐g‐glycidyl azide) graft copolymers using N,N‐dithiocarbamate‐mediated iniferters

A glycidyl azide polymer with pendent N, N‐diethyl dithiocarbamate groups (GAP‐DDC) was prepared by the reaction of poly(epichlorohydrin) (PECH) with pendent N, N‐diethyl dithiocarbamate groups (PECH‐DDC) and sodium azide (NaN₃) in dimethylformamide (DMF). It was then used as a macro‐photoinitiator for the graft polymerization of methyl methacrylate (MMA). Photopolymerization was carried out in a photochemical reactor at a wavelength greater than 300 nm. Conversion was determined gravimetrically and first‐order time conversion plot for the polymerization system showed linear increase with the polymerization time indicating that polymerization proceed in controlled fashion. The molecular weight distribution (M_w/M_n) was in the range of 1.4–1.6 during polymerization. The formation of poly(methyl methacrylate‐g‐glycidyl azide) (PMMA‐g‐GAP) graft copolymer was characterized by gel permeation chromatography, FT‐IR spectroscopy, Thermogravimetric analysis, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

端叠氮基聚叠氮缩水甘油醚的合成与热性能

以不同多元醇为起始剂,环氧氯丙烷经阳离子开环聚合得到不同结构的端羟基聚环氧氯丙烷(PECH-OH),将其端羟基进行磺酰化改性得到端磺酸酯基聚环氧氯丙烷(PECH-OTS),随后的叠氮化反应中叠氮基同时取代PECH-OTS的端磺酸酯基和侧基中的氯得到目标产物。用IR、GPC、TG和DSC对不同结构的GAPA进行了表征。结果表明,GAPA-2、GAPA-3和GAPA-4的数均相对分子质量分别为810、830和1190,玻璃化转变温度分别为-67.5、-63.8和-58.6℃,端叠氮基聚叠氮缩水甘油醚(GAPA)的热分解可分为相对独立的叠氮基热分解(250℃)和聚醚主链热分解。     

Structure and mechanical properties of fluorine‐containing glycidyl azide polymer‐based energetic binders

A novel energetic polymer, fluorine‐containing glycidyl azide polymer (FGAP ), was developed via an initial cationic copolymerization of epichlorohydrin and 1,1,1‐trifluoro‐2,3‐epoxypropane, followed by azidation. The structure of FGAP was confirmed using Fourier transform infrared, ¹H NMR and ¹³C NMR spectroscopies. The molecular weight and the thermal behavior of FGAP were characterized using gel permeation chromatography, differential scanning calorimetry and thermogravimetric analysis. FGAP had a molecular weight of 2845 g mol^?1, and the glass transition temperature and decomposition temperature were found to be ?47.8 and 253 °C, respectively. FGAP ‐based polyurethane networks were further prepared using triphenylmethane‐4,4,4‐triisocyanate as the crosslinking agent. In comparison with GAP , FGAP ‐based polyurethane networks exhibited better mechanical behaviors (a tensile strength of 1.5 MPa and an elongation at break of 81.6%). The results demonstrated that FGAP might be a promising polymeric binder for future propellant formulations. © 2017 Society of Chemical Industry     

新型高能聚合物GAP的热分解和燃烧

简要回顾了GAP的研究历程及应用情况，介绍了有关GAP的特点及研究现状，着重阐述了GAP热分解及燃烧过程的特点，给出了目前比较先进的实验方法及手段，如色谱—质谱联用、热解质谱、分子束质谱、红外激光、紫外激光、CO2激光诱导热解等，可供进一步研究GAP参考。     

GAP基含能热塑性弹性体的合成与表征

以聚叠氮缩水甘油醚(GAP)为软段,1,4-丁二醇(BDO)和4,4′-二苯基甲烷二异氰酸酯(MDI)为硬段,采用熔融预聚体法合成了GAP基含能热塑性弹性体(ETPE)。研究了扩链剂加料方式、催化剂用量、异氰酸酯指数、硬段含量等因素对弹性体力学性能的影响。采用傅里叶变换红外光谱(FT-IR)、凝胶渗透色谱(GPC)、热台显微镜、差示扫描量热(DSC)、热重分析(TG)表征了ETPE的性能。结果表明,采用恒速滴加扩链剂方法合成的ETPE具有良好的热稳定性和力学性能。当催化剂质量分数为0.6‰,异氰酸酯指数(R)为0.98,硬段质量分数(Y)为35%时,热塑性弹性体的数均相对分子质量为52 312,软化点为96℃,拉伸强度为14.52MPa,断裂伸长率为518.78%。     

含能增塑剂研究进展(续)

(接上期第 2 5页 )3　 2种含能基团3.1　硝酸酯基 +硝基在 2 0 0 1年第 32届火炸药年会上瑞典国防研究所的DetlefDrees将 2 ,2 二硝基 1,3 二硝氧基丙烷(NPN) [2 7] 与其他 2种增塑剂进行比较 ,结果见表 5。表 5　NPN与其他增塑剂性能比较性能Bu NENABDNPF/ANPN　相对分子质量 2 0 7　 42 6　 2 5 6　氧平衡 / % -10 4.3　 -5 7.5　 12 .5　密度 / (g·cm- 3) 1.2 2　 1.3 9　 1.66　熔点 /℃ -9　 -15　Tg(纯物质 ) /℃ -83 .5　 -65 .2　 -81.5　Tg(PNIMMO与增塑剂　质量比为 5 0∶5 0 ) /℃ -70 .1　 -4 8.5　 -64 .6　粘…     

Thermal interaction between polymer‐based composite friction materials and counterfaces

Attempts have been made to improve the performance of polymeric composite friction materials for eliminating undesirable mechanical and thermal effects on the opposing surfaces. Elastic compression modulus and thermal conductivity of the moulded friction materials were found to be the most effective parameters upon the thermal interaction between the disc and brake pad. Effects of elastic modulus on temperature accumulation of the interface have also been studied. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 364–369, 2001     

Synthesis,spectral and DSC analysis of glycidyl azide polymers containing different initiating diol units

Glycidyl azide polymers (GAPs), containing different diol units, were prepared by treating the corresponding poly(epichlorohydrin)s (PECHs) with sodium azide in DMF solvent at 110°C for 8–10 h. The poly(epichlorohydrin)s containing different diol units were synthesized by the polymerization of epichlorohydrin using borontrifluoride etherate as initiator in the presence of a small amount of low molecular weight diols. The formation of these PECHs was confirmed by IR spectroscopy. The nature of terminal hydroxyl group present in the polymer chain was confirmed by proton NMR spectroscopy. The structure of GAPs containing different initiating diol units was confirmed by UV, IR, and proton NMR spectral analysis. Thermal properties of the GAPs were evaluated using differential scanning calorimetry; the stabilities and glass‐transition temperatures of the GAPs varied according to the initiating diol unit present in the polymer chains. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2157–2163, 2004