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通过γ射线辐照交联异型聚丙烯腈(PAN)纤维解决了低分子量聚丙烯腈半碳化中的熔融坍塌问题, 提高了PAN的半碳化稳定性; 采用傅里叶变换红外光谱、 元素分析及核磁共振波谱确定了辐照交联机理. 同时, 根据辐照产生的不同交联度与PAN硫化后载硫量的变化关系, 探讨了硫化聚丙烯腈(SPAN)锂硫电池正极材料的储硫机理. 利用拉曼光谱及X射线光电子能谱等分析手段表征了SPAN中硫原子的反应位置, 说明PAN主链上的亚甲基所在的碳为与硫化学结合的活性位点, 为探究SPAN结构提供了新的依据. 交联度升高对硫化后所形成的SPAN正极材料的电化学稳定性起促进作用, 容量保持率可提升至98%. 相似文献
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基于Monte Carlo模拟的化学反应动力学参数估算 总被引:2,自引:0,他引:2
提出并采用基于MonteCarlo模拟与动力学实验相结合的化学反应动力学参数估算方法,由基元反应确定MonteCarlo模拟具体做法,将MonteCarlo模拟结果与动力学实验结果相比较,根据比较结果自动调整和优化动力学参数,从而无需事先确定动力学方程即可有效估算各种化学反应的动力学参数值.采用该方法估算了丙烯氨氧化反应动力学参数,并对估算结果进行了分析与讨论. 相似文献
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轮胎硫化工艺的设定取决于各组成部件的硫化参数,最终决定轮胎的硫化效率、能耗和成品质量,硫化参数的精确性至关重要。橡胶制品的硫化交联反应符合1级动力学方程,白炭黑填充胶料的硫化反应不单有硫磺-促进剂的交联反应,还存在白炭黑极性团聚的物理作用,直接使用硫变仪检测数据无法精确表征其硫变行为。基于此,本文对白炭黑填充母炼胶(未加硫)的硫变行为进行研究,表明了白炭黑团聚作用在硫变测试时对扭矩提升的干扰。最后,对白炭黑填充终炼胶和对应母炼胶的硫变曲线依据“时间-扭矩”数据进行“相减”处理,重新绘制出能够更精确表征硫化动力行为的曲线,更好地指导含白炭黑胶料的轮胎硫化工艺设定。 相似文献
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设计了一个数值模型来模拟一个反应物在明胶层中边扩散边在油珠界面上与另一个反应物反应的动力学过程。提出了处理油珠界面反应的动力学方程,并应用在模型设计中。采用模型模拟与动力学实验测量相结合的方法不仅可以获得反应物在明胶层中的扩散系数和界面反应的比速率常数等重要动力学参数,而且可以提供反应物和生成物在明胶层中的时空分布,并预测不同条件下的动力学过程。对模型的适用性也作了详细的讨论。 相似文献
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化学反应动力学是燃烧过程分析的重要工具。燃烧微观反应过程、复杂反应机理、燃烧实验测量和湍流燃烧数值模拟等方面的研究工作已经取得了长足进步。本文主要介绍燃烧反应动力学研究方法,包括电子结构方法、燃烧反应热力学和速率常数的计算方法、燃烧详细机理构建和简化、反应力场分子模拟以及燃烧中间体测量、燃料点火延迟和光谱诊断等方面的研究现状。燃烧反应动力学具有很强的应用背景,燃烧过程化学物种的反应速率计算是湍流燃烧数值模拟的一个中心任务。由于燃烧反应网络的高度复杂性,我们对燃烧机理的认识还远不清楚。化学反应和湍流相互作用研究的深入、燃烧反应动力学和计算流体力学的协同发展,将对新燃料设计、燃烧数值模拟、发动机内流道流场结构的准确描述产生深远影响。 相似文献
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复合金属氧化物脱硫剂脱除SO2动力学 总被引:2,自引:2,他引:2
利用热重实验装置考查了SO2、O2浓度及反应温度对复合金属氧化物脱硫剂脱硫反应的本征及宏观反应速率的影响。根据流-固相非催化反应理论,采用Marquart非线性回归法由实验数据求得动力学参数。经检验表明,以幂函数表达本征动力学是合理的,随机孔模型可很好地模拟宏观动力学规律。 相似文献
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戊二醛蒸汽交联明胶材料的性能研究 总被引:1,自引:0,他引:1
利用戊二醛蒸汽对明胶材料进行交联改性。研究了交联反应时间对明胶材料力学性能、溶出性能和溶胀特性的影响。研究发现,随着交联时间的延长,交联反应从明胶瓣表面至内部逐步进行,由此可获得交联度呈梯度变化的明胶材料。研究结果表明,明胶材料的拉伸强度、模量和冲击强度随交联反应时间的延长而增加,而溶出速率和溶胀率随交联反应时间的延长而减小。蒸汽交联明胶材料的溶胀动力学不能用二次速率方程来描述。 相似文献
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On the basis of the quantitative relationship among rubber processing, structure and property, the methodology of the integrated processing-structure-property analysis on rubber in-mold vulcanization is presented, and then the temporal evolution and spatial distribution characteristics of silicone rubber hot processing parameters, crosslinking structure parameters and mechanical property parameters are obtained by means of the finite element method. The present work is helpful for optimizing curing conditions, and then the design of rubber vulcanization processes according to certain requirements can be done. 相似文献
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Controlling and assuring the quality of the manufacture of high precision engineering rubber components has led to the need to simulate fundamental industrial processes such as compression molding and injection molding using CAE tools. Both compression and injection molding techniques for the fabrication of rubber products involve crosslinking or vulcanization which is invariably assisted by temperature and pressure. Vulcanization is a chemical process and therefore its simulation necessarily involves characterization of kinetic parameters. The kinetics of curing or vulcanization is somewhat complex as it depends upon the compound formulation, temperature and in some cases pressure. The present paper reports and discusses the application and utility of different techniques for characterizing the cure behavior of rubber compounds. Kinetic data has been fitted to various mathematical models in order to see which of the models can best represent the crosslinking behavior of selected rubber compounds. Finally, the kinetic data is used to simulate the injection molding process for relatively simple geometries. 相似文献
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Hidetaka Tobita 《Journal of Polymer Science.Polymer Physics》1993,31(10):1363-1371
A new theory to predict the molecular weight distribution in free radical polymerization that includes chain transfer to polymer is proposed. This theory is based on the branching density distribution of the primary polymer molecules. The branching density distribution provides the information on how each chain is connected to other chains, and therefore, a full molecular weight distribution can be calculated by application of the Monte Carlo simulation. The present theory accounts for the history of the generated branched structure and can be applied to various reaction systems that involve branching and crosslinking regardless of the reactor types used. The present simulation confirmed the validity of the method of moments in a batch polymerization proposed earlier. It was shown clearly why gelation never occurs by chain transfer to polymer without the assistance of other interlinking reaction such as bimolecular termination by combination. © 1993 John Wiley & Sons, Inc. 相似文献
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To investigate the reaction kinetics of hydrogen combustion at high-pressure and high-temperature conditions, we constructed a ReaxFF training set to include reaction energies and transition states relevant to hydrogen combustion and optimized the ReaxFF force field parameters against training data obtained from quantum mechanical calculations and experimental values. The optimized ReaxFF potential functions were used to run NVT MD (i.e., molecular dynamics simulation with fixed number of atoms, volume, and temperature) simulations for various H(2)/O(2) mixtures. We observed that the hydroperoxyl (HO(2)) radical plays a key role in the reaction kinetics at our input conditions (T ≥ 3000 K, P > 400 atm). The reaction mechanism observed is in good agreement with predictions of existing continuum-scale kinetic models for hydrogen combustion, and a transition of reaction mechanism is observed as we move from high pressure, low temperature to low pressure, high temperature. Since ReaxFF derives its parameters from quantum mechanical data and can simulate reaction pathways without any preconditioning, we believe that atomistic simulations through ReaxFF could be a useful tool in enhancing existing continuum-scale kinetic models for prediction of hydrogen combustion kinetics at high-pressure and high-temperature conditions, which otherwise is difficult to attain through experiments. 相似文献
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Iron (III) acetylacetonate (Fe (acac)) in the presence of triethanolamine (TEOA) was utilized as a novel crosslinking agent for halogenated diene rubber. Following the assumption that the mechanism of the crosslinking bases on the Heck-type reaction mechanism, which requires the presence of a halogen and an unsaturated carbon-carbon double bond, chloroprene rubber (CR) and brominated butyl rubber (BIIR) were utilized as rubber matrices. The results of FTIR spectra analysis confirm the proposed mechanism and indicate that a Heck-type reaction is feasible for performing a crosslinking of halogenated diene rubbers. The use of the Fe (acac)/TEOA curing system results in a significant torque increase during the vulcanization, which confirms the high activity of those compounds. The elimination of halogen from a rubber macromolecular structure or elimination of a basic environment of the crosslinking reaction results in a deactivation of the new curing system. 相似文献
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Prashant A. Bhadane John Cheng Maria D. Ellul Basil D. Favis 《Journal of Polymer Science.Polymer Physics》2012,50(23):1619-1629
In this study, a dynamic vulcanized alloy of brominated poly(isobutylene‐co‐p‐methylstyrene) (BIMSM) and polyamide (PA) has been investigated. An interfacial reaction between BIMSM and PA and a crosslinking reaction between BIMSM molecules is carried out simultaneously during melt blending. To form a vulcanized, nanoscale elastomer dispersion, the timing of these reactions is key and the interfacial reaction should be well advanced before the vulcanization reaction initiates. At a blending temperature of 205 °C, independent of the processing conditions, it is found that the interfacial reaction dominates the phase morphology development. Increasing the melt processing temperature, however, begins to favor the vulcanization reaction over the interfacial reaction. In nonplasticized blends, it is found that increasing the temperature above 235 °C increases the speed of the vulcanization reaction to a level that it dominates the phase morphology development. As a result, the phase size increases by 2.5‐fold because the system is vulcanized before the interfacial modification step is complete. Adding plasticizer to the PA matrix increases the overall phase size, but shows a similar behavior with increase in temperature from 205 to 255 °C. The critical temperature where the vulcanization reaction starts dominating phase morphology in the plasticized systems is at 225 °C. Once the processing temperature is above the critical temperature, it is found that the mixing sequence can be used to time and decouple the reactions. The work demonstrates that a close control over the temperature and processing conditions can be used to decouple the interfacial and vulcanization reactions resulting in vulcanized, nanoscale dispersions for the BIMSM and PA system. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献