Characterization of BAMO/NMMO Copolymers

The compositions and microstructures, thermolyses, and sensitivities of 3,3-bis(azidomethyl)oxetane (BAMO) copolymers with 3-nitratomethyl-3-methyloxetane (NMMO) were characterized. The molar ratios of monomers fed in the copolymerizations were: BAMO/NMMO = 8/2, 7/3, and 6/4. The observed compositions were 81/19, 68/32, and 60/40, respectively. The relative compositions of trade microstructures were also exactly the same as theoretical values. The copolymerization of BAMO with NMMO behaved like an ideal system in the sense that the copolymer has approximately the same composition as the monomer fed. The microstructures of copolymers were also randomly arranged. Poly BAMO showed side chain decomposition in the initial stage of the thermolysis, on the other hand, backbone decomposition controlled the thermolysis of poly NMMO. The BAMO units and the NMMO units appeared to decompose more or less independently of one another and retained their individual decomposition characteristics despite being copolymerized. However, the heat generated by the NMMO decomposition, which occurred at 40°C lower than that of BAMO. activated the reaction of BAMO. Poly B/N(7/3) showed very interesting characteristics in sensitivities, mechanical properties, and the heat of decomposition.     

Thermal Decomposition of BAMO Copolymers

The effects of copolymerization of THF, as an inert component, AMMO, as an energetic one and NMMO, as a nitrate ester, with BAMO on their thermal decomposition are reported here. Although the thermal decomposition of the BAMO and NMMO units in B/N(7/3) carry out independently and the heat generated by the NMMO unit decomposition accelerates the BAMO unit decomposition, the THF and AMMO units do not affect that of the BAMO unit in B/T(7/3) and B/A(7/3). One exothermic peak in DSC is shown for B/A(7/3) and B/T(7/3) except for B/N(7/3) which shows two peaks. One peak at lower temperature is from the NMMO unit decomposition and the other is from the BAMO unit. The rate of decomposition of B/A(7/3) is the same as that of poly(BAMO), which indicates that the reactivity of the AMMO unit is equal to that of the BAMO unit. In propellant, containing 75% HMX and 25% copolymer binder, burning rate of B/A(7/3)/HMX is faster than that of B/N(7/3)/HMX. Although the heat of decomposition for B/A(7/3) in DSC is smaller than that for B/N(7/3), that of B/A(7/3)/HMX is larger than that of B/N(7/3)/HMX. The reaction occurred in the condensed phase of the propellant, therefore, may play an important role in the combustion.     

Burning Rate Augmentation of BAMO Based Propellants

Thermal decomposition and the burning properties of BAMO based propellants with HMX or AN/HMX have been investigated. The heat generated by the azide binder decomposition initiated and accelerated the thermal decomposition of HMX and AN. Ammonium perchlorate (AP) and lead stearate with carbon black significantly altered the mechanisms of the thermal decomposition and the burning properties of the HMX based propellants. AP showed an increase in burning rate with a slight decrease in burning rate pressure exponent. The lead catalyst yielded high value of the burning rate with the lowest pressure exponent. The ammonium dichromate also influenced the mechanisms of the thermal decomposition and the burning properties of the AN/HMX samples. The combination of ammonium dichromate and copper chromite was the most effective on the burning rate augmentation of AN/HMX based propellants. AN sublimed and evaporated from the condensed phase and mainly reacted exothermically in the gas phase HMX and AN/HMX based propellants showed smokeless burning characteristics in the small rocket motor combustion tests.     

BAMO/NMMO Copolymer with Polyester Initiation

In order to improve of mechanical properties at low temperature region, 3,3-bis(azidomethyl)oxetan (BAMO), 3-nitratomethyl-3-methyloxetane (NMMO) and polyester (PE) copolymer were synthesized by using polyester initiator with boron trifluoride etherate. The molar ratio of each units in the BAMO/NMMO/PE copolymer was 7.4/2.6/0.39 according to the ¹H-NMR spectrum analysis and was almost exactly the same composition as the monomer fed (7/3/0.33). The relative composition of triad microstructures was same as theoretical value and they were randomly arranged. The PE, which was a replacement of 1,4-butanediol, acted as an excellent soft segment in the copolymer, and the glass transition point of the elastomer was 4.8 degrees lowered by the replacement. This effect was also verified in the mechanical properties of the composite propellant and the tensile elongation was increased from 15% to 40%percnt; at −40 °C.     

Thermal Decomposition of BAMO/HMX Propellants

Thermal decomposition of BAMO [bis(azidomethyl)oxetane/tetrahydrofuran copolymer]/HMX composite propellants was studied by isothermal TGA (thermogravimetric analysis) and DSC (differential scanning calorimetry) in helium atmosphere, which was showing overall two steps first-order kinetics. The effects of cross-link ratio on the accelerated aging of the BAMO/HMX propellants were also measured with infrared spectroscopy and gas chromatography. The accelerated aging was conducted at 347 K for several weeks. BAMO/HMX propellants for a very low cross-link ratio made the cavity between HMX and BAMO binder by N₂, CO₂, and H₂O evolutions during accelerated aging. An exotherm, generated by the decomposition of azide binder, initiated and accelerated the thermal decomposition of HMX. The burning rate of BAMO/HMX propellant was larger than those of BAMO binder and HMX, respectively. However, the propellant could not maintain the combustion at low pressure, at which its burning rate was equal to that of BAMO binder.     

3,3-双(叠氮甲基)氧杂环丁烷/四氢呋喃共聚醚的合成

以季戊四醇为原料经氯化、碱性关环、取代叠氮化合成了３,３－双（叠氮甲基）氧杂环丁烷,采用三氟化硼乙醚在０℃引发３,３－双（叠氮甲基）氧杂环丁烷和四氢呋喃本体聚合,合成了具有能量特征的叠氮共聚醚并用ＩＲ和１ＨＮＭＲ表征了分子结构,运用１３ＣＮＭＲ和ＧＰＣ分析了聚合物的分子量和端基性质。     

BAMO废水中叠氮根含量测定

研究了3,3-双（叠氮甲基）环氧丁烷（BAMO）废水中叠氮根含量的测定方法。考察了入射波长、酸度、显色剂用量、反应温度和时间等对测定体系的影响。加入3ml pH为6的NaOH-KH2PO4缓冲液,再加入2ml体积分数1％CS2．乙醇溶液和2ml质量分数0．3％CPC溶液,控制水浴温度20～30℃下反应1h,318nm处测定吸光度,能够得到较满意的分析结果。标准曲线为Y=0．0061x＋0．009,线性相关系数R^2=0．9998。方法的适用范围为0～7mg／L。     

相转移催化法合成BBMO和BAMO

以1,1,1-三溴甲基-1-羟甲基甲烷为原料、水和甲苯为反应溶剂、季铵盐为相转移催化剂,在NaOH的作用下经关环反应合成3,3-双溴甲基氧杂环丁烷(BBMO);以季铵盐为相转移催化剂,BBMO在水相介质中经叠氮基取代反应制备出3,3-双叠氮甲基氧杂环丁烷(BAMO);用红外、核磁表征产品结构,高效液相色谱分析产品纯度.结果表明,BBMO收率与纯度分别为81%和97.2%;BAMO收率与纯度分别为80.9%和98.37%.用相转移催化法制备BBMO和BAMO具有收率高、纯度高、安全性好等特点.     

Energetics of AMMO

The thermal decomposition process and combustion wave structure of azide polymer were studied to determine the parameters which control the burning rate. The azide polymer studied was 3-azidomethyl-3-methyl oxetane (AMMO) which contains energetic –N₃ groups. From the experiments, it was found that the thermal decomposition process of AMMO consists of a two-stage weight loss process: the first-stage corresponds to an exothermic reaction which is caused by the scission of N-N₂ bond, and the second-stage corresponds to the decomposition of the remaining fragments. The burning rate of AMMO is approximately 50% of the burning rate of GAP propellant and is as high as that of conventional double base propellant. The heat feedback from gas phase to the burning surface increase with increasing pressure. The burning surface temperature and the heat of reaction at the surface decrease with increasing pressure.     

相转移催化法合成BBMO和BAMO

以1，1，1-三溴甲基-1-羟甲基甲烷为原料、水和甲苯为反应溶剂、季铵盐为相转移催化剂，在NaOH的作用下经关环反应合成3，3-双溴甲基氧杂环丁烷（BBM0）；以季铵盐为相转移催化剂，BBMO在水相介质中经叠氮基取代反应制备出3，3-双叠氮甲基氧杂环丁烷（BAM0）；用红外、核磁表征产品结构，高效液相色谱分析产品纯度。结果表明，BBMO收率与纯度分别为81％和97．2％；BAM0收率与纯度分别为80．9oA和98．37％。用相转移催化法制备BBMO和BAMO具有收率高、纯度高、安全性好等特点。     

BAMO/AMMO基ETPE的合成与性能

以3-溴甲基-3-甲基氧杂环丁烷(BrMMO)为单体,聚合形成溴代聚醚.叠氮溴代聚醚为叠氮聚醚PAMMO;以3,3-双叠氮甲基氧杂环丁烷(BAMO)为单体,直接开环聚合形成叠氮聚醚PBAMO.以四氢呋喃为溶剂,PBAMO为硬段预聚物,PAMMO为软段预聚物,甲苯二异氰酸酯(TDI)为二异氰酸酯单体,丁二醇氨酯型齐聚醇为扩链剂,按照一步法溶液聚合工艺,制成了数均分子量在25000左右的含能热塑性弹性体(ETPE).ETPE具有可熔可溶的特点,室温抗拉强度和延伸率约为5MPa和400%.     

Characterization of P(BAMO/AMMO) ETPE Prepared Using Different Diisocyanates

Poly(3,3‐bisazidomethyl oxetane/3‐azidomethyl‐3‐methyl oxetane) energetic thermoplastic elastomers (P(BAMO/AMMO) ETPEs) is one of the most valuable ETPEs in the field of energetic binders. P(BAMO/AMMO) ETPEs were prepared using different diisocyanates (TDI, HMDI, IPDI, and HDI) to investigate the influence of the diisocyanate on the performance of P(BAMO/AMMO) ETPEs. Mechanical properties and heats of formation were investigated. FT‐IR spectroscopy results showed that TDI‐based ETPE has the highest degree of hydrogen bonding with a value of 69.00 %. Mechanical test results showed that the TDI‐based ETPE has better mechanical property with maximum stress at 5.24 MPa and breaking elongation at 390 %. The order for degree of hydrogen bonding and mechanical property of different diisocyanate‐based ETPEs was TDI>HMDI>IPDI>HDI. The heats of formation were calculated by the group additivity method and by the heat of combustion method. The values of heats of formation for TDI‐based ETPE were 3.44 kJ g⁻¹ and 3.75 kJ g⁻¹ according to the two methods. Additionally, TDI‐based ETPE has a lager heat of formation than the other ETPEs.     

Surface Energetics and Adhesion

The relationships between surface energetics and adhesion are critically reviewed. New data that confirm such relationships, for peel tests as well as lap shear tests, are presented. The effect of hydrothermal aging of aluminum surfaces on surface energetics can be used to predict degradation in bond strength. The mechanism of failure for elastic adhesives (such as Scotch ® tape) in peel tests may be essentially the same as for more brittle adhesives (such as epoxies) in lap shear tests. This mechanism may involve brittle fracture that forms a critical flaw at the adherend-adhesive interface (on a microscopic level), followed by crack propagation which then may include considerable elastic and plastic deformation. The locus of propagation (fractography) is generally not (but may be) relevant to the problem of how to remedy mechanical weakness in an adhesive joint, since the local region of critical flaw formation rather than the general surface area determines the joint strength.     

BAMO/AMMO三嵌段共聚物的合成、表征及热分解动力学

以三氟化硼.乙醚/1,4丁二醇作引发体系,利用阳离子开环共聚合的方法合成出3,3′-双叠氮甲基环氧丁烷/3-叠氮甲基-3′-甲基环氧丁烷(BAMO/AMMO)三嵌段共聚物。用FTIR、1HNMR和GPC对共聚物的结构和相对分子质量进行了表征,用DSC测定了共聚物的玻璃化转变温度。结果表明,合成的BAMO/AMMO三嵌段共聚物的相对分子质量可控、且分布窄,并具有含能热塑性弹性体的性质。同时用Vyazovkin的非线性无模型函数方法研究其热分解动力学,得到叠氮基团的分解活化能约为150kJ/mol。三嵌段共聚物在叠氮基团分解之后形成了交联网络结构。     

含能单体BAMO热稳定性研究及其组成的表征

通过热失重-差热（TGA-DTA）分析，初步研究了3，3-双（叠氮甲基）氧杂环丁烷（BAMO）热失重过程的变化规律。结合红外光谱分析谱图对BAMO热稳定性进行了表征，采用气相色谱仪对BAMO组成进行分析检测，建立了BAMO组成气相色谱分析方法。该气相色谱分析法具有较好的重复性和再现性，且快速、易行，可作为BAMO产品及中控常规检测方法。     

Energetics of point defects in TiC

Density functional theory was used to evaluate the energetics of point defects in TiC_x (x < 1): C vacancies and Al substitution at a C site. Our ambition is to contribute towards understanding the underlying atomic mechanisms enabling the Al intercalation into TiC_x and the subsequent formation of Ti₃AlC₂. The difference between the energy of formation for an Al substitution at a C site and a bulk C vacancy is 0.224 eV. Furthermore, only 49 meV/vacancy is required to order the existing bulk C vacancies. Surface effects were also considered: the energy of formation for Al on TiC(1 0 0) at a vacant surface C site is smaller by 2.779 eV than in the case of the C surface vacancy, indicating that Al is likely to be incorporated. Based on these energy differences, it is reasonable to assume that Ti₃AlC₂ is formed by Al surface ingress into TiC_x and that vacancy ordering takes place.     

Energetics of Nitro/Azide Propellants

A new type of double-base propellant which contains GAP was studied in order to elucidate the burning rate characteristics and combustion wave structure. This class of propellants is termed “nitro/azide propellants”. Experimental results revealed that the burning rate and temperature sensitivity are increased when 12.5% DEP is replaced with 12.5% GAP. The reaction rate in the dark zone is increased by the replacement of DEPo with GAP. However, the gas phase structure of NG/NC/GAP propellant is fundamentally the same as that of NG/NC/DEP propellant and the basic chemical reaction mechanism in the gas phase zone remains unchanged for both propellants.     

Preliminary Characterization of Propellants Based on p(GA/BAMO) and pAMMO Binders

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.     

Energetics and structures of carbon nanorings

Molecular dynamics (MD) simulation is adopted to study the stability of carbon nanorings, where the force-field function describes the interactions of the carbon atoms. A nanoring is formed by bending a straight nanotube (n, m) and connecting its two ends together. Both armchair and zigzag nanorings are investigated, and the critical diameters for stable nanorings are obtained. It is found that zigzag nanorings have a larger critical diameter than armchair nanorings.