抗氧剂3114合成反应热力学和动力学的研究

研究了常温溶剂法合成抗氧剂3114反应热力学和动力学过程。控制温度在117±2℃,研究结果表明,反应是零级反应,反应速率常数k=1.91×10-3/min,反应的平衡常数K=138.4(mol/L)-6,反应活化能Ea=1366.2J/mol。     

Methods to determine solubility parameters of polymers at high temperature using inverse gas chromatography

Experimental values of Flory–Huggins parameters, χ, between polymers and probes, are frequently used to determine the solubility parameters of the polymers by the method of DiPaola–Baranyi and Guillet. The solubility parameters of probes were usually estimated by using heat of vaporization. When χ is measured at a temperature near the critical temperature of the probes and used to determine the solubility parameter of polymers, the departure of enthalpy of the probe vapor from the ideal gas state should be considered. This study discussed the method to make the correction and its effect on the determination solubility parameter of polymers. Without correction in the vapor phase enthalpy, the solubility parameters of the probes and polymer tend to be underestimated and the error increases when the critical temperature is approaching. Analytical expressions for the effect of correction on the solubility parameter of probes and parameters of polymers were derived. By use of probes with a range of solubility parameters on both sides of the solubility parameter of polymers, the correlation between parameters of polymers was shown to be reduced. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1547–1555, 2004     

超高交联树脂吸附酚类的热力学研究与机理探讨

合成和表征了超高交联树脂AM-1，以大孔吸附树脂Amberlite XAD-4为参照，比较研究了其在水溶液中吸附邻硝基苯酚，对硝基苯酚的吸附行为和热力学性质，测定了不同温度下的平衡吸附量，Langmuir模型和Freundlich模型均能很好拟合。利用Freundlich模型求得△H、△G、△S。研究发现，AM-1型树脂比表面小于XAD-4型树脂的比表面，而吸附能力却更强。这得益于其更多的微孔体积及表面活性基团。     

An improved prediction result of entropic‐FV model for vapor–liquid equilibria of solvent–polymer systems

In this work, entropic expressions of UNIFAC‐FV and Entropic‐FV models were evaluated by using an extensive database of infinite dilution vapor–liquid equilibrium (VLE) data of athermal systems containing polypropylene, polyethylene, and polyisobutylene. For the infinite dilution athermal systems, performance of the Entropic‐FV model was better than that of the UNIFAC‐FV model. Then, finite concentration VLE data of non‐athermal systems that consisted of 16 polymers and 36 solvents containing a large variety of solvent–polymer systems ranging from nonpolar to polar substances were considered to optimized 46 pairs of group interaction parameters of the Entropic‐FV model. For systems containing polar solvents of three types of solvents studied, revised group interaction parameters gave significant improvements from 17.9 to 13.0% average absolute deviation (AAD) of solvent activities. For overall results, improvements were achieved from 15.1 to 12.4% AAD. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1145–1153, 2005     

Activity–Composition Relations in NiAl2O4─MnAl2O4 Solid Solutions and Stabilities of NiAl2O4 and MnAl2O4 at 1300° and 1400°C

Activities of NiO were measured in the oxide and spinel solutions of the system MnO–NiO–Al₂O₃ at 1300° and 1400° C with the aim of deriving information on the thermodynamic properties of the spinel phases. Synthetic samples in selected phase assemblages of the system were equilibrated with metallic nickel and a gas phase of known oxygen partial pressures at a total pressure of 1 atm. The data on NiO activities and directions of conjugation lines between coexisting oxide and spinel phases were used to establish the activity–composition relations in spinel solid solutions at 1300° and 1400°C. The MnAl₂O₄–NiAl₂O₄ solid solutions exhibit considerable negative deviations from ideality at these temperatures. The free energy of formation of MnAl₂O₄ from its oxide components (MnO + Al₂O₃) at 1300° and 1400°C is calculated to be −24.97 and −26.56 kJ. mol⁻¹, respectively. The activities determined in the stoichiometric spinel solid solutions are more negative as compared with those predicted from cation distribution models.     

Activity–Composition Relations of Chromium Oxide in Silicate Melts at 1500°C under Strongly Reducing Conditions

The solubility and activity–composition relations of chromium oxide in melts of the systems CaO–CrO _x –SiO₂ and CaO–Al₂O₃–CrO _x –SiO₂ have been determined at 1500°C by equilibrating melts with Pt–Cr alloys at known oxygen pressures. It is shown that the increase in the concentration of divalent chromium ions, as the oxygen pressure and the basicity of melt decrease, results in a dramatic increase in the solubility of chromium oxide in the liquid phase. An increase in the Al₂O₃ content of the melt leads to a decrease in the solubility of chromium oxide over the whole composition range studied. The activity coefficient of CrO has been found to increase with increasing melt basicity and decreasing oxygen pressure whereas the activity coefficient of CrO_1.5 decreases sharply with increasing melt basicity for siliceous melts but levels off at a basicity ratio (wt% CaO/wt% SiO₂) of about 0.7. An increase in the Al₂O₃ content of the melts results in an increase in the activity coefficient of CrO.     

糠醛渣对染料甲基紫的吸附行为

以废弃物糠醛渣为原料制备吸附剂,研究了甲基紫溶液在糠醛渣上的吸附行为,并从热力学和动力学角度探讨了吸附作用机理。吸附平衡模型研究表明,糠醛渣对甲基紫的吸附符合Langmuir与Freundlich型的复合型吸附,即单层吸附和吸附剂表面非均质吸附同时存在;吸附动力学研究表明,糠醛渣对甲基紫的吸附符合准二级吸附动力学方程;热力学参数,ΔG0为-6.667 kJ.mol^-1--8.216kJ.mol^-1、ΔH0为16.866kJ.mol^-1、ΔS0为0.079 kJ.mol^-1.K^-1、为14.753 kJ.mol^-1,说明糠醛渣对甲基紫的吸附是自发进行的、吸热的,且主要为一物理吸附过程。糠醛渣作为吸附剂处理甲基紫废水,是一种有效的方法。该方法实现了以废治废的废物资源化目标,具有良好的社会效益和经济效益.     

不可逆空气热泵循环供热率密度优化

基于有限时间热力学理论,以供热率密度作为热力学优化目标,分析了恒温热源不可逆空气热泵循环的性能,导出了供热率密度与压比和换热器有效度等参数间的解析关系式,并由数值计算分析了热源温比、总热导率及压缩机和膨胀机效率等对热导率最优分配及供热率密度最优性能的影响特点。     

利用AFM对单晶硅表面加工化学反应理论分析

以原子力显微镜为工具,在空气条件下对单晶硅片表面加工得到下凹的三维微结构。给出了AFM金刚石针尖在对单晶硅的微加工中的化学反应和加工模型。对加工条件下发生的化学反应及其原理进行了理论分析。用化学热力学定律、化学动力学原理和相关的热力学数据自由能、生成热、化学键能、活化能等分析加工过程中发生的反应是空气中O2与单晶硅Si反应生成二氧化硅的过程;金刚石针尖磨损发生的反应主要是空气中O2与金刚石针尖C反应生成CO2的过程。     

基于非平衡态热力学的传递唯象研究

从广义力与流的角度,探讨了传递现象的共同本质,即各种强度量势场梯度作用下的能流和流。运用非平衡态热力学的相关理论,推导了多势场影响下的传递唯象方程。根据非平衡态热力学分析不可逆过程的一般步骤,提出确定传递唯象方程力与流的两种方法,体现了热力学和传输学在传递研究中的学科交叉。对热电耦合现象的应用分析表明,基于非平衡态热力学的传递唯象方程,能够完整、深入地揭示不可逆效应之间的耦合关系。