季戊四醇四硝酸酯及其五氟硫基衍生物性能的理论研究

运用密度泛函B3LYP方法,以6-31G*为基组,对季戊四醇四硝酸酯(PETN)和它的4个五氟硫基(—SF_5)取代物五氟硫基季戊三醇三硝酸酯(PPTN)、二-五氟硫基季戊二醇二硝酸酯(PDPDN)、三-五氟硫基季戊醇硝酸酯(PTPN)和四-五氟硫基季戊烷(TPNT)进行了研究,优化了它们的分子几何构型,进行了振动频率分析,计算预测了它们的密度、热力学函数、爆轰性能和可能的热分解引发键的解离能。结果表明,5种化合物中,PPTN的密度和爆轰性能更好,且PPTN的稳定性优于PETN;随着—SF_5数目的增多,化合物的密度增大;但—SF_5数目过多时,化合物的爆速和爆压反而降低。PPTN的能量和稳定性满足高能量密度化合物(HEDC)的指标要求。     

硝酸羟胺的热稳定性评估及热分解机理研究

为评估氧化剂硝酸羟胺的热稳定性,使用标准液体铝皿于3K/min、4K/min、5K/min加热速率下进行热分析。借助非等温DSC曲线的参数值,应用Kissinger法和Ozawa法求得热分解反应的表观活化能和指前因子,根据Zhang-Hu-Xie-Li公式、Hu-Yang-Liang-Xie公式、Hu-Zhao-Gao公式以及Zhao-Hu-Gao公式,计算硝酸羟胺的自加速分解温度和热爆炸临界温度,并对热分解机理函数进行了研究。设计了7条热分解反应路径,采用密度泛函理论B3LYP/6-311++G(d,p)方法对硝酸羟胺的热分解进行了动力学和热力学计算。计算结果表明,硝酸羟胺热分解的自加速分解温度TSADT=370.05K,热爆炸临界温度Tbe0=388.68K,Tbp0=397.54K,热分解最可几机理函数的微分形式为f(α)=17×(1-α)18/17。硝酸羟胺热分解各路径中,动力学优先支持路径Path 6、Path 5、Path 4和Path 1生成NO和NO_2,其次是Path 2、Path 7和Path 3生成N2和N_2O。温度在373K以下时,Path 1′反应无法自发进行,硝酸羟胺无法进行自发的热分解。从热力学的角度来看,硝酸羟胺在370.05K以下储存是安全的。     

硝酸异丙酯对双基推进剂的热分解性能影响研究

为研究云爆剂中硝酸异丙酯渗露对双基推进剂的热分解性能影响,采用加速量热仪(ARC)对双基推进剂在加入硝酸异丙酯环境下的热分解情况进行测试,得到其绝热分解的温度、压力时间曲线,利用速率常数法计算出样品的活化能和指前因子等动力学参数。研究发现在加入硝酸异丙酯后,双基推进剂的起始热分解温度升高,表观活化能变大,表明硝酸异丙酯会提高双基推进剂的热稳定性。     

用扭辫分析法研究纤维素硝酸酯塑溶胶体系的固化过程

扭辫分析方法(简称TBA)是六十年代出现的一种动态力学性能试验方法。本文利用TBA法研究了纤维素硝酸酯与丙三醇三硝酸酯(NC-NG)和纤维素硝酸酯与硝化三乙二醇(NC-TEGDN)两种塑溶胶体系的固化过程。得到了这两种体系的动态力学谱图,并作出了NC-NG固化过程的三T状态图,为固化过程工艺条件选择提供了理论依据。由研究结果发现,纤维素三硝酸酯在增塑剂中的物理固化过程有着与热固性树脂相类似的固化现象,即有明显的物理凝胶和玻璃化现象。而且物理凝胶时间与温度的关系符合凝胶反应动力学规律。     

激波驱动下硝酸异丙酯的分散变化规律研究

研究液滴的分散过程对于阻止火灾蔓延、提高内燃机效率、改进云雾爆轰武器和提高云雾爆轰控制技术有着重要的作用。通过高速摄影技术以及压力测量系统,着重研究液态燃料硝酸异丙酯（IPN）的分散过程,分析液膜厚度和激波强度对IPN液膜分散的影响。IPN液膜初始阶段以水平方向的分散为主;随后,以竖直方向的分散为主。水平方向,液膜抛洒先进入减速阶段,随着液膜厚度H的增加,液膜分散效果变差,分散需要的时间更长,其分散表征与石油醚相似。IPN液膜分散所需能量要高于石油醚。激波强度超过某个值之后,超压比ε随液膜厚度H呈线性变化,可以为液膜分散提供足够的能量。当H＜12 mm时,IPN液膜的分散变化过程主要受激波强度影响;当H＞12 mm时,IPN液膜的分散变化过程主要受液膜厚度影响。     

纤维素硝酸酯在MWCNTs/PMMA复合体系中的助分散作用

引进一种碳纳米管的分散剂纤维素硝酸酯,研究纤维素硝酸酯在MWCNTs/PMMA复合体系中的助分散作用和可能的机理。通过观察MWCNTs在液体中的沉降情况评价纤维素硝酸酯的助分散效果;采用原位本体聚合法制备MWCNTs/PMMA复合材料并测试其耐划痕性和硬度。观察实验显示,酸处理和未酸处理的MWCNTs均能够稳定地悬浮于含有纤维素硝酸酯的MMA溶液中。测试结果表明,含有纤维素硝酸酯的酸处理MWCNTs/PMMA复合材料的耐划痕性比纯PMMA的提升了67%,布氏硬度提升了14%。纤维素硝酸酯的使用解决了MWCNTs在基体单体MMA中的沉降问题,其助MWCNTs分散作用优良。     

NG/TEGDN混合硝酸酯废酸安全处理工艺研究

研究采用稀释后热分解法处理硝化甘油/二缩三乙二醇二硝酸酯(NG/TEGDN)混合硝酸酯合成过程中产生的废酸的工艺参数。研究表明:处理后废酸是较理想的稀释介质,处理后废酸/处理前废酸流量比为2.5~3.0、处理温度为150~180℃、真空度为0.02~0.04 MPa、流量为1.8~2.0 L/min时,废酸处理效果较好,处理后废酸中酯含量0.5%,能稳定达标排放,且不影响安全和连续化生产。     

硝酸异丙酯与空气混合物的爆轰性能研究

采用立式激波管对硝酸异丙酯(IPN)与空气混合物的爆轰极限、起爆能、爆压和爆速进行了测定,同时从理论上对该燃料的爆轰参数作了计算,计算结果与实验值吻合较好.实验结果证明了IPN的临界起爆能与燃料当量比成"U"形曲线关系;该结果对防止意外事故有一定的指导意义.     

3,5-二硝基吡唑-4-硝酸酯的合成及热分解机理研究

以4-氯吡唑为原料,经过硝硫混酸硝化制得4-氯-3,5-二硝基吡唑,再以硝酸根为亲核试剂进行亲核取代反应得到一种新型的含能化合物3,5-二硝基吡唑-4-硝酸酯,并采用红外光谱、核磁共振、元素分析对产物结构进行了表征。计算了爆轰性能并与常规含能化合物进行了比较。采用TG-DSC-MS联用方法对其热分解机理进行了研究。结果表明,3,5-二硝基吡唑-4-硝酸酯的爆轰性能接近于黑索金与奥克托金而优于梯恩梯。DNPN的热分解机理可能是,首先O—NO_2键断裂,接着硝基吡唑发生硝基自由基或者亚硝基自由基断裂,最后吡唑环开环生成N_2、NO、N_2O以及CO_2等产物。     

硝酸熔盐储热材料在太阳能利用中的研究进展

随着全球经济的快速发展,能源危机日渐凸显,太阳能作为可再生能源的一种,越来越受到人们的重视.因此,如何高效利用太阳能资源值得深究.熔盐具有良好的蓄热特性,在石化、电池及冶金行业中发挥着很大的作用,尤其可以作为传热蓄热介质应用于太阳能热发电和太阳能制氢中.其中硝酸盐的特性较为适合用于熔盐储热材料.主要针对硝酸熔融盐体系,一是介绍了硝酸熔融盐体系在太阳能方面的应用,二是介绍了国内外学者对此体系的物化性质研究,如工作温度范围、热力学性质及热稳定性等.通过对比,总结了不同混合熔融盐各项性能的异同.指出了硝酸熔融盐性能深入研究的方向,为硝酸熔盐在能源开发利用和环境保护等方面发挥更重要的作用提供了重要参考.     

Preparation,damping and thermal properties of potassium titanate whiskers filled castor oil-based polyurethane/epoxy interpenetrating polymer network composites

A series of potassium titanate whiskers (PTW) filled castor oil-based polyurethane (PU)/epoxy resin (EP) interpenetrating polymer network (IPN) composites were prepared. The damping properties, thermal stability as well as tensile strength of the IPN composites were studied systematically in terms of composition. Results revealed that the addition of PTW can significantly improve the damping properties of pure PU/EP IPN and can improve the thermal decomposition temperature. Tensile tests showed that the tensile strength of the IPN composites was improved after the incorporation of PTW. It is expected that the PTW filled IPN composites may be used as structural damping materials.     

Damping analysis of polyurethane/epoxy graft interpenetrating polymer network composites filled with short carbon fiber and micro hollow glass bead

A series of short carbon fiber (CF) and micro hollow glass bead (HGB) filled polyurethane (PU)/epoxy resin (EP) graft interpenetrating polymer network (IPN) composites were prepared. The damping properties, thermal stability properties as well as tensile and impact strength of IPN composites were studied systematically. Results revealed that the addition of short carbon fiber and micro HGB can significantly improve the damping properties of pure PU/EP IPN and can improve the thermal decomposition temperature. Mechanical tests showed that the tensile strength of the IPN composites could be improved after the incorporation of short carbon fiber and micro HGB, while the impact resistance of the composites was impaired after the addition of micro HGB. It is expected that the carbon fiber and micro HGB filled IPN composites may be used as structural damping materials.     

PF／PnBA IPN的合成及相容性研究

本文采用乳液和溶液聚合法合成PF/PnBA IPN,并对产物进行了动态力学性能、热重分析及微观形态研究。结果表明,IPN可使组分相容性得到提高热性能得以改善,乳液聚合与溶液聚合法合成IPN产物的微观形态有所不同。     

Morphology,mechanical and thermal properties of nano-structured full IPNs based on polyisoprene and PMMA

Morphology, mechanical properties, thermal stability and gas transport behaviour of interpenetrating polymer networks (IPNs) based on PI/PMMA have been investigated using various techniques. Crosslinking level of both phases and concentration of PMMA were found to have noticeable effects on the compatibility of immiscible components during IPN formation. Effect of crosslinking was studied by preparing IPNs with varying amount of crosslinker concentration in each phase. Crosslinking of both phases facilitated deeper interpenetrations between both networks, and certain degree of compatibility is attained during IPN formation. Nanometre-sized domains were observed for highly crosslinked IPN. Lower concentration of PMMA was found to favour phase mixing more effectively than others. DSC curve of 65/35 IPN showed a broad transition arising from the α and β-relaxations of PMMA due to the higher flexibility attained by mixing with the highly mobile PI chains. The mechanical properties of the IPNs were correlated to the morphology of the system and 50/50 composition showed maximum mechanical properties among the studied compositions. Mode of mechanical failure, thermal stability and gas transport behaviour were also analysed. IPNs having nanometre-sized domains showed least gas permeability among the studied samples.     

Two-step synthesis of polyacrylamide/poly(vinyl alcohol)/polyacrylamide/graphite interpenetrating network hydrogel and its swelling,conducting and mechanical properties

Polyacrylamide/poly(vinyl alcohol)/polyacrylamide/graphite interpenetrating network (PAM/PVA/PAM/G IPN) hydrogel is synthesized using a simple two-step polymerization method. The swelling behaviors of the hydrogel depend on the PVA, graphite, and crosslinker dosages, and swelling process is dominated by a relaxation of macromolecule chains. Owing to IPN structure, the hydrogel shows a good mechanical strength and thermal stability. On the other hand, the incorporation of graphite improves the conductivity of the hydrogel.     

聚氨酯/环氧树脂互穿聚合物网络半硬泡沫的结构与性能

采用同步法合成了聚醚型聚氨酯/环氧树脂互穿聚合物网络半硬泡沫.通过FTIR,DMA,SEM研究了IPN半硬泡沫的化学结构、动态力学性能以及微观结构形态.FTIR分析表明了聚氨酯和环氧树脂的网络间存在接枝反应.很宽组成比范围内IPN半硬泡沫均显示出单一的宽温域玻璃化转变,而且该转变随着环氧树脂含量的增加向高温方向移动.通过SEM发现IPN半硬泡沫泡孔结构形状都比较均一.循环加载压缩发现所有IPN泡沫不仪压缩性能好而且具有很好的回弹性,大变形压缩后泡沫儿乎不变形,重复使用性能好.     

聚氨酯/环氧树脂互穿网络半硬泡沫的热稳定性

制备了聚氨酯/环氧树脂互穿网络半硬泡沫,通过热重分析(TGA)研究了其热分解,计算了各分解阶段的热分解反应动力学参数。结果表明,氮气中,互穿聚合物网络(IPN)泡沫根据环氧树脂含量不同其分解过程有2~3个失重阶段,随着环氧含量增加,第一阶段的失重率减小,第二阶段的失重率增大。IPN泡沫在第一、二两阶段总的热失重率低于纯聚氨酯泡沫及纯环氧树脂。环氧树脂含量为30%(质量分数,下同)时泡沫的热稳定性最好。预测IPN半硬泡沫在100℃氮气中失重5%时的热老化寿命可达2.4E7年,表明IPN泡沫具有很好的热稳定性。     

蒙脱土改性PU/EP IPN的研究

本文通过端异氰酸酯基聚氨酯预聚体与环氧树脂E-51形成了互穿网络,并通过热重分析仪(TGA)研究了完全固化后的互穿网络的热分解行为;透射电镜研究了IPN的相分离行为及用拉伸强度,断裂伸长率对其进行了力学性能的表征.结果表明,经过环氧树脂改性的聚氨酯的耐热性能比纯聚氨酯得到了提高,且力学性能也有所改善.并选取性能较好的PU/EP IPN,用纳米级有机蒙脱土对其进行了改性.研究发现,经有机纳米蒙脱土改性的PU/EP IPN的力学性能及耐热性有了进一步的提高.     

Aliphatic amine cured PDMS-epoxy interpenetrating network system for high performance engineering applications—Development and characterization

A siliconized epoxy interpenetrating network (IPN) was synthesized from commercially available DGEBA epoxy resin GY250 (Ciba-Geigy, epoxy equivalent = 182–192, viscosity = 9000–12000 cP) and hydroxyl terminated polydimethylsiloxane (PDMS). PDMS and GY250 were thoroughly mixed at 30°C to get the prepolymer. Stoichiometric amounts of PDMS-epoxy prepolymer, γ-aminopropyltriethoxysilane, aliphatic amine curing agent (HY951), and dibutyltindilaurate catalyst, were thoroughly mixed and cast in a mould after evacuating the entrapped air. The cured material was then taken out and post cured at 70°C for 10 h. IPN was characterized by FTIR spectroscopy, SEM, DSC, TGA and viscosity measurements. Incorporation of PDMS in the epoxy matrix increased the viscosity and lowered the exotherm and pot-life. PDMS in IPN increasedT _g, heat-distortion temperature and reduced the percentage weight loss with increase in temperature. Incorporation of PDMS drastically reduced the tensile and flexural strengths and hardness. By reducing the tensile and flexural modulus, the siloxane moiety effectively reduced the internal stress of IPN thereby improving its impact strength and percentage elongation. PDMS increased the electric potential gradient of IPN to withstand without breakdown. An increase in the tracking index and arc resistance of IPN were observed, because of the presence of Si-O-Si, which minimized the possibility of forming carbonized path. Volume and surface resistivities of IPN also increased with the incorporation of PDMS. The siliconized epoxy IPN, with better impact and thermal resistance, may be used in automobile and aerospace applications to withstand high temperature, and mechanical stress. The PDMS-epoxy IPN may be used for encapsulation, high temperature and high voltage application due to their low shrinkage and lesser internal stress. With the improved electrical characteristics, IPN may be used for high performance electrical insulation, insulator housings, and encapsulation to withstand high voltage, moisture, oxidation, chemical attack, biological attack, outdoor weathering, contamination, electrical, mechanical and thermal stress.     

Thermo- and pH-sensitive IPN hydrogels based on PNIPAAm and PVA-Ma networks with LCST tailored close to human body temperature

Interpenetrating polymer network (IPN) hydrogels based on chemically modified poly(vinyl alcohol) (or PVA-Ma), with different degrees of substitution (DS), and poly(N-isopropylacrylamide) (or PNIPAAm) were obtained and characterized in this work. The PVA-Ma/PNIPAAm membrane hydrogels were prepared in two steps. In the first step the PVA-Ma hydrogels (with using PVA-Ma with different DS) were prepared by the reaction of double bonds on PVA-Ma, using the persulfate/TEMED pathway. In the second step the PNIPAAm network was prepared within the parent PVA-Ma network at different PVA-Ma/NIPAAm ratios using a photoreaction pathway. The studies show that degree of swelling of PVA-Ma/PNIPAAm IPN hydrogels is dependent on both temperature and pH of the soaking solution. The LCST of PVA-Ma/PNIPAAm IPN hydrogels, which was determined by measuring the intensity of light transmitted through the swollen hydrogels, can be tailored closer to human body temperature. Furthermore, SEM images showed that the IPN hydrogels present characteristic morphology as compared to parent PVA-Ma networks. IPN hydrogels presented lower cytotoxicity as compared to respective PVA-Ma hydrogels but the increase in the PVA-Ma/NIPAAm ratio allows the respective hydrogels being lesser cytocompatibles. The IPN hydrogels synthesized in this work presented characteristics that potentize their application as biomaterials, drug carriers, artificial muscles and treatment of wound.