正硅酸乙酯原位聚合改性淀粉膜的制备和性能

采用正硅酸乙酯(TEOS)原位聚合改性制备了淀粉膜,研究了其性能。当TEOS用量为淀粉的25%时,膜的力学性能最好,拉伸强度和断裂伸长率分别为16.91 MPa和24.88%。此外,还进行了电子能谱仪、扫描电子显微镜、X射线衍射和降解性测试。结果表明,淀粉膜中Si元素含量与添加量吻合,硅羟基与淀粉分子中的羟基发生了脱水缩合反应;淀粉膜表面均一平整,结晶度低,热塑性、降解性良好,是一种可完全生物降解的环保材料。     

大颗粒超高纯度硅溶胶的制备及其表征(英文)

采用新工艺路线制备四乙氧基硅烷（tetraethoxysilane,TEOS）,以TEOS为原料制备超纯度大颗粒硅溶胶。TEOS是烷氧基硅烷法制备甲硅烷的副产物,经过精馏提纯以后,加入盐酸或氨水催化剂,采用溶胶-凝胶法制备硅溶胶。结果表明：TEOS和硅溶胶金属杂质离子总含量都低于0.3mg/L。用盐酸催化TEOS水解制备溶胶,胶粒直径达到129nm;用氨水催化,胶粒直径达272nm。当物质的量比n（C2H5OH）/n（TEOS）=6,n（H2O）/n（TEOS）=5,搅拌速度为250 r/min,制备的硅溶胶胶粒均匀度最好。加水不搅拌,胶粒很容易发生团聚,但是,当搅拌速率高于500 r/min时,胶粒出现团聚现象。     

仿生物矿化制备硅纳米材料

利用正硅酸乙酯和人工合成的多肽,在比较温和的条件下快速合成了硅纳米材料,并研究了制备过程中的多种因素对产物形貌的影响,研究发现:在pH值=8.0的磷酸盐缓冲液中,当R5肽的浓度为10 mg/mL,正硅酸乙酯的浓度0.1mol/L,反应15min时,可得到规则的球状颗粒。X射线能谱分析证明产物为硅和多肽的复合物。     

Synthesis of High Surface Area Silica Gels Using Porous Carbon Matrices

Porous silica was prepared using the sol-gel synthesis with porous carbon matrices as a pore-forming support. Tetraethoxysilane (TEOS) was hydrolyzed in an acid medium in the presence of a substoichiometric amount of water. Various carbon materials were used, among them Sibunit and catalytic filamentous carbon. Carbon matrices were impregnated with hydrolyzed TEOS and dried, then carbon was removed by burning out in air at 873 K. The obtained porous silica samples were studied by adsorption and electron microscopic methods. The specific surface area as high as 1267 m²g and pore volume as high as 5.7 cm³/g were determined for some silica samples. Thus deposited SiO₂ was found to cover the carbon surface copying its surface. With CFC used as carbon matrix, silica nanotubes were obtained. Thermostability of such silica is significantly greater as compared to silica gels reported earlier.     

Methanol Decomposition Over Copper/Silica: Effect of Temperature and Co-reactant on Carbon Deposition

The interaction of methanol with a copper/silica catalyst at 373 and 523K under reducing, oxidising and inert carrier gas flows has been studied. Under all conditions there is retained material associated solely with the copper. In general the retained species is adsorbed methanol/methoxy; only over an oxidised catalyst after treatment at 523K is there no evidence for adsorbed methanol/methoxy. Desorption of carbon dioxide is associated with an up-take in dioxygen indicating oxidation of a surface species, probably formate. After laydown under reducing or inert gas flow, the copper does not re-oxidise under the TPO gas flow, even at temperatures >673K indicating that material is still retained by the copper. Bulk re-oxidation of the reduced catalyst in the absence of retained species is rapid at 293K. Under oxidising conditions at 523K there is no evidence for adsorbed methanol/methoxy on the surface of the copper; in this case the retained species may be more akin to a carbonate.     

含能材料燃烧过程中热分解化学的研究进展

从模拟燃烧条件、组分相互作用、组分物理状态、分析测试技术等几方面介绍了含能材料燃烧过程中热分解化学研究近几年来的最新进展。着重介绍燃烧热分解中的基元反应对建立推进剂燃烧新型模型的重要性、氧化剂和黏合剂及催化剂之间的相互作用、氧化剂的黏度和相态变化对燃烧和热分解过程的影响。     

Further Understanding of the Chemistry of Manganese‐Induced Peroxide Decomposition

Manganese is the most effective catalyst for the hydrogen peroxide decomposition during peroxide bleaching used in the pulp and paper industry. We studied the chemistry involved in this project. The results showed that Mn²⁺ and Mn³⁺ are present during the course of the reaction. We followed the Mn²⁺ and Mn³⁺ concentrations during the course. It was found that a steady state of Mn³⁺ concentration was attained until the hydrogen peroxide concentration was zero. At this time, the Mn³⁺ concentration was maximum, then it decreased due to the disproportionation to form MnO₂. Removal of O₂ from the system slowed down the rate of decomposition. The detailed reactions involved were discussed.     

Effect of pH on the Chemistry of the Barium Titanium Citrate Gel and Its Thermal Decomposition Behavior

In this investigation, X-ray diffractometry and ¹³C NMR spectroscopy were used to characterize the effect of pH on the formation of gel and its thermal decomposition by the Pechini process. It was found that the major effect of pH was to destroy the esterification between citric acid (CA) and ethylene glycol, which in turn could influence Ba species and the formation of a mixed-metal CA complex. It was also found that barium carbonate was derived from the Ba species and was not related to the instability of Ba₂Ti₂O₅CO₃, but Ba₂Ti₂O₅CO₃ was formed by the thermal decomposition of a mixed-metal CA complex. Moreover, BaTiO₃ formed via two routes, the reaction of BaCO₃ with Ti species and thermal decomposition of Ba₂Ti₂O₅CO₃.     

Microporous Materials Derived from the Thermal Decomposition of the Titania/PDMS Hybrid Particles

A microporous material containing titania nano-particles was obtained by thermal decomposition of the titania/silicone hybrid spherical particles. The titania/silicone hybrid spherical particles were converted to porous silica with the BET surface area of about 360 m²/g by heat treatment at 400^∘C in air, while the spherical morphology of the particles was retained. The thermal decomposition of the organic groups of the hybrid particles was accompanied with the generation of the micropores and the transformation of the silicone to silica. The thermal decomposition of the organic groups and the micro-structural change of the hybrid particles were investigated by XRD, N₂ adsorption/desorption isotherm, CHN elemental analysis, FT-IR, and solid-state ²⁹Si magic angle spinning (MAS) NMR.     

Decomposition Chemistry of TAGN

Triaminoguanidine nitrate (TAGN) is a unique energetic material which produces relatively low molecular weight combustion products. TAGN is characterized by the oxidizer fragment “HNO₃” that is attached by an ionic bond in the molecular structure. In this study, various types of experiments were conducted in order to elucidate the physicochemical decomposition process of TAGN. The exothermic rapid reaction observed at the early stage of the decomposition is the process representing the nature of energetics of TAGN. This exothermic reaction occurs immediately after the endothermic phase change from solid to liquid. Since the weakest chemical bond consisting in the TAGN molecule is the N N bond (159 kJ/mol), the initial bond breakage should be the amino groups and the NH₂ radicals split off. The energy released by the dissociation of the NH₂ radicals (104.3 kJ/mol) is the heat produced at the early stage decomposition of TAGN. Thus, the burning rate of TAGN is considered to be dominated by the dissociation of the NH₂ radicals. It must be noted that the burning rate of TAGN is almost double that of HMX even though the energy contained in the unit mass of TAGN is less than that of HMX. The HNO₃ attached to the molecular structure of TAGN is not the fragment to produce the exothermic rapid reaction observed at the early stage decomposition process.     

Effect of Low-Energy Accelerated Ion Bombardment on the Properties of Metal-Organic Decomposition Derived SrBi2(Ta,Nb)2O9 Thin Films Processed at Low Temperature

Ferroelectric SrBi₂(Ta,Nb)₂O₉ (SBTN) thin films were deposited on Pt (200 nm)/TiO _x (40 nm)/SiO₂ (100 nm)/Si substrates by metal-organic decomposition. The effects of bombardment from accelerated argon and oxygen ions on the properties of SBTN thin films were investigated. It was found that the argon ion bombardment could decrease the crystallization temperature owing to the increase of internal energy of the films. Also, the oxygen vacancies at the interface between the SBTN film and platinum bottom electrode or at grain boundaries in the film were passivated through the oxygen ion treatment, resulting in the improved electrical properties. By optimizing the process parameters and using bombardment of accelerated argon and oxygen ions, SBTN films with good ferroelectric and electrical properties could be obtained, at a temperature as low as 650°C.     

溶胶-凝胶法制备PET/SiO2纳米复合材料及其TG、DSC分析

采用溶胶-凝胶（sol-gel）法，将正硅酸乙酯和水加入到制备聚对苯二甲酸乙二酯（PET）的中间产物对苯二甲酸双羟乙酯(BHET)中,在液态下均匀混合，高温下快速发生溶胶-凝胶反应，再按PET缩聚反应制得PET/SiO₂纳米复合材料。通过TEM、TG、DSC对材料进行了表征和研究。结果表明，SiO₂在PET中均匀分散，其尺寸在10～100 nm之间，PET/SiO₂纳米复合材料的热降解活化能较普通PET有明显提高，但初始降解温度和结晶性能均有所降低。     

聚酰胺12非等温热分解动力学研究

在不同升温速率下,利用热重分析法研究了聚酰胺12（PA12）在氮气氛围中的热分解动力学。运用Freeman Carroll、Kissinger、Ozawa、Achar和Coats Redfern方法计算和确定了PA12在氮气氛围中的热分解活化能和热分解机理及其模型。结果表明,在氮气氛围中,PA12的热分解活化能为246.5 kJ/mol,指前因子为1014.71;PA12热分解机理为收缩球体法则,机理方程的微分形式为f(α)=3(1-α)2/3,积分形式为G(α)=1-(1-α)1/3。     

Decomposition of Dolomite Monitored by Neutron Thermodiffractometry

Dolomite powder from Coín (Spain) was heated in air at a constant rate of 2°C/min to 1000°C, while neutron diffraction patterns were collected every 150 s. Rietveld refinement was applied and raw intensity data were used to monitor decomposition. The full process happened in two stages: dolomite decomposition to give calcite and periclase, and calcite breakup. The first stage activation energy was 47 kcal·mol⁻¹ from fitting to a contracting sphere model. The dolomite mean thermal expansion coefficients were (6.7 ± 0.4) × 10⁻⁶ and (2.7 ± 0.2) × 10⁻⁵ K⁻¹ along the a and c axes, respectively. Changes in the Ca–O and Mg–O bond distances were also measured.     

RDX和HMX的热分解III.分解机理

简述RDX和HM X热分解的各种机理,其热分解的初始过程是N-N和C-N键断裂的竞争反应,试验条件和样品相态等因素影响竞争过程。用DSC-FT IR联用技术和热裂解原位池/FT IR分析了主要分解气相产物和凝聚相中主要官能团的变化。结果表明,RDX和HM X热分解的主要分解气相产物为N2O,CH2O,CO,CO2,H2O和HCN。RDX的分解气相产物CH2O和H2O红外吸收率的温度关系曲线都产生双峰,RDX基团-NNO2的吸收带1 589 cm-1和1 278 cm-1有两个不同速率的变化过程。用N-N键和C-N键竞争断裂的观点解释了RDX与HM X热分析和产物分析的结果。     

阿莫西林的热分解行为研究

利用热重分析（TG）采用不同升温速率（5,10,15,20,30℃/min）在氮气气氛下对阿莫西林热分解动力学进行了研究。采用Coats-Redfern和Ozawa热分析处理动力学数据的方法,计算阿莫西林热分解反应活化能E及指前因子A。结果表明,阿莫西林的热分解反应为一级反应,在15%～35%的失重率时热分解表观活化能为51.43～56.34 kJ/mol,指前因子lgA值为8.76～9.38。     

脱硫石膏料球的分解

为研究脱硫石膏在成球状态下的分解特性,根据石膏分解气固反应和固固反应机制,探索脱硫石膏料球分解反应的影响因素及其影响规律。研究结果表明:脱硫石膏料球很难在弱还原性气氛条件下分解;在掺入石油焦作为固体还原剂后,脱硫石膏能够较好地实现分解。正交实验结果表明:掺入石油焦的脱硫石膏料球较优的分解条件为:分解温度1 200℃、分解时间30 min、碳硫摩尔比n(C)/n(S)为1.0、料球粒径为5~7 mm。     

介孔薄膜制备的研究进展

为了使介孔薄膜更广泛地应用于分离、催化、化学传感器、发光材料和太阳能电池等方面,人们对其合成与应用进行了研究.文章综述了近年来高度有序介孔薄膜制备方法、表征技术,介绍了介孔SiO2薄膜和介孔TiO2薄膜的研究进展,并对介孔薄膜未来的发展进行展望.     

二氯丙烯胺的热分解动力学

用热分析的方法研究了二氯丙烯胺的热分解动力学,起始分解温度在120℃左右,并用无模式函数法计算出反应活化能、指前因子。     

水中臭氧的分解动力学研究

在尽可能地排除UV、传质及自由基吸收剂等影响的情况下,在 293.2~298.5K和pH3.2~13.0条件下,用Stopped-Flow光谱仪研究了O3在水中分解反应动力学。pH3.2~13.0条件下,O3分解相对于O3的反应级数为1级。在pH 10.1~10.3之间,OH-或pH对O3分解的影响可能有一个突变点。pH 10.1~10.3以下(含pH 10.1点),O3分解相对于OH-反应级数平均为0.13, 在pH 10.1~10.3以上(含pH 10.3点),O3分解相对于OH-反应级数为1.37。在pH 10.1~10. 3以下时,O3分解活化能为146.7kJ穖ol-1。