EA/MMT纳米复合材料的制备及其光固化动力学研究

通过4 - 溴甲基二苯甲酮与二甲基正十八胺反应合成的季铵盐光引发剂苯甲酰苄基二甲氨基十八烷基溴化铵(BDOB),进行插层修饰蒙脱土(MMT),通过层间引发聚合法光固化制备环氧丙烯酸酯/蒙脱土(EA/MMT)纳米复合材料;利用红外光谱法对EA/MMT的光固化行为进行了研究.XRD和TEM分析结果表明,MMT在光固化复合材料中已得到插层和部分剥离;增加光引发剂浓度及提高环境温度均可提高其固化速率和双键最终转化率,氧气的存在使体系的诱导期延长,双键转化率降低;光固化反应总级数约为6～7,表观活化能为9.8 kJ/mol.     

烯丙基乙烯基醚锂1,2-迁移机理研究

以从头算方法（6－31G基组）研究了烯丙基乙烯基醚锂化物发生乙烯基从氧到碳上的1，2－迁移的机理，乙烯基烯丙基同锂试剂（RLi)反应，但尚未重排前，烯丙基端的C3－O醚键就已断裂，则不是锂离子和烯丙基负离子呈负离子对形式存在，过渡态构型类似一个二聚代的反式三元环结构，重排反应的活化能较高（137.4kJ/mol)，然而整个反应的放热效应也相当高（176.5kJ/mol)，因而它是一个反应速度相当快的重排反应。     

(S)-N-甲基脯氨醇催化甲基乙烯基酮与苯甲醛的不对称Baylis-Hillman反应的理论研究

采用密度泛函DFT-B3 LYP方法在6-31＋G＊基组下研究了（S）-N-甲基脯氨醇催化甲基乙烯基酮与苯甲醛的不对称Baylis-Hillman反应,得到了反应中各物种的优化构型及其电子能量,获得了反应势能面,同时考虑水和1,4-二氧六环的溶剂效应,解释了该不对称反应的立体选择性.     

二烷氨基香豆素在烯烃和聚合物中的荧光行为

7-二乙氨基-4-甲基香豆素(DAMC)在液态烯烃和固态聚合物介质中的激发(吸收)波长和发射波长随介质的极性增大而红移。DAMC在聚合物介质中荧光量子产率和荧光寿命决定于介质的极性,辐射失活速率常数与非辐射失活速率常数也与此相关。处在单线激发态的DAMC与活泼烯烃会发生化学反应。据此说明DAMC的单线激发态构型为扭动两性离子是合理的。     

Kinetics of thermal decomposition of hydrated minerals associated with hematite ore in a fluidized bed reactor

The kinetics of removal of loss on ignition (LOI) by thermal decomposition of hydrated minerals present in natural iron ores (i.e., kaolinite, gibbsite, and goethite) was investigated in a laboratory-scale vertical fluidized bed reactor (FBR) using isothermal methods of kinetic analysis. Experiments in the FBR in batch processes were carried out at different temperatures (300 to 1200℃) and residence time (1 to 30 min) for four different iron ore samples with various LOIs (2.34wt% to 9.83wt%). The operating velocity was maintained in the range from 1.2 to 1.4 times the minimum fluidization velocity (U_mf). We observed that, below a certain critical temperature, the FBR did not effectively reduce the LOI to a desired level even with increased residence time. The results of this study indicate that the LOI level could be reduced by 90% within 1 min of residence time at 1100℃. The kinetics for low-LOI samples (<6wt%) indicates two different reaction mechanisms in two temperature regimes. At lower temperatures (300 to 700℃), the kinetics is characterized by a lower activation energy (diffusion-controlled physical moisture removal), followed by a higher activation energy (chemically controlled removal of LOI). In the case of high-LOI samples, three different kinetics mechanisms prevail at different temperature regimes. At temperature up to 450℃, diffusion kinetics prevails (removal of physical moisture); at temperature from 450 to 650℃, chemical kinetics dominates during removal of matrix moisture. At temperatures greater than 650℃, nucleation and growth begins to influence the rate of removal of LOI.     

Sm3+掺杂LnNbO4(Ln=La,Y)红色荧光粉的性能分析

通过高温固相法合成系列Sm3+掺杂LnNbO4(Ln=La,Y)红色荧光粉,并对样品的物相结构、荧光特性、衰减寿命和荧光热猝灭等性能进行实验分析。分析结果表明:合成的样品不含杂质相,可以被近紫外光LED和蓝光LED芯片有效激发,发出色坐标为(0615 5,0380 2)的红光对于LnNbO4(Ln=La,Y)基质来说,Sm3+掺杂LaNbO4基质的荧光强度比较强,最佳的Sm3+掺杂浓度为2%;随着Sm3+掺杂浓度的提高衰减寿命曲线由单指数线形变双指数线形,且衰减寿命不断变短;Sm3+之间的电偶极 电偶极作用是导致荧光浓度猝灭发生的原因;样品在293~450 K这一温度范围内具有良好的热稳定性。说明Sm3+掺杂的LaNbO4红色荧光粉具备成为白光LED用红色荧光粉的潜力。     

Investigation of the kinetic mechanism of the demanganization reaction between carbon-saturated liquid iron and CaF2-CaO-SiO2-based slags

The demanganization reaction kinetics of carbon-saturated liquid iron with an eight-component slag consisting of CaO-SiO₂-MgO-FeO-MnO-Al₂O₃-TiO₂-CaF₂ was investigated at 1553, 1623, and 1673 K in this study. The rate-controlling step (RCS) for the demanganization reaction with regard to the hot metal pretreatment conditions was studied via kinetics analysis based on the fundamental equation of heterogeneous reaction kinetics. From the temperature dependence of the mass transfer coefficient of a transition-metal oxide (MnO), the apparent activation energy of the demanganization reaction was estimated to be 189.46 kJ·mol-1 in the current study, which indicated that the mass transfer of MnO in the molten slag controlled the overall rate of the demanganization reaction. The calculated apparent activation energy was slightly lower than the values reported in the literature for mass transfer in a slag phase. This difference was attributed to an increase in the "specific reaction interface" (SRI) value, either as a result of turbulence at the reaction interface or a decrease of the absolute amount of slag phase during sampling, and to the addition of calcium fluoride to the slag.     

温度对乙烯在TiCl_4/MgCl_2-Al(i-Bu)_3上聚合动力学的影响

研究了聚合温度(T)对乙烯在负载型TiCl_4/MgCl_2-Al(i-Bu)_3体系催化剂上聚合动力学的影响,在其他条件相对固定下,聚合速度(R)、活性中心浓度(C~*)和链增长速度常数(K_p)随温度升高而增大,而聚乙烯分子量(MW)则随温度升高而降低,求出体系的表观活化能(Ea)为29kJ/mol.根据测得的数据,讨论了温度在活性衰减、链转移反应和活性中心生成中的作用.     

HBr2 +离子的结构及其解析势能函数

 采用密度泛函（B3LYP）方法,以及6-311++G(2df,2pd)基组优化出了单态HBr⁺²离子的结构参数、离解能和力常数。在此基础上,利用多体项展式方法导出了HBr₂⁺（C_s,X¹ A′）离子的分析势能函数,并获得其势能面,正确的再现了HBr₂⁺离子的平衡结构特征及其离解能,并可由势能图观察到Br(² P_u )+HBr⁺ (X² Π_i)→HBr₂⁺（X¹ A′）反应通道上出现一个鞍点,其位置在R_BrBr=0.42 nm,R_HBr=0.16 nm,∠HB_r B_r=97.5°,V=-5.5 eV,垒高约0.53 eV。为进一步探讨HBr₂⁺离子的反应动力学过程打下了基础。     

微波加热与常规加热硅锰粉固相脱硅动力学比较

采用微波加热和常规加热对硅锰粉和巴西粉锰的脱硅反应进行了动力学行为研究,以巴西粉锰为脱硅剂,与硅锰粉中的硅发生氧化还原反应.微波加热和常规加热分别加热到不同温度并保温一定时间,测定产物中硅含量并计算固相脱硅反应的表观活化能.实验表明:单一和混合料均可在微波场中快速升温.随着温度的升高和保温时间的延长,两种加热方式脱硅率均随之提高,在相同实验条件下,微波加热的脱硅率和反应速率均高于常规加热,微波加热可以提高固相脱硅率;微波加热固相脱硅反应的限制性环节为扩散环节,其表观活化能为102.93 kJ·mol-1,常规加热脱硅反应的表观活化能为180 kJ·mol-1,说明微波加热能改善固相脱硅的动力学条件,提高固相脱硅反应速率,降低脱硅反应的活化能.