聚合物溶液及液体的状态方程研究

【作者】 仲崇立；

【导师】 卢焕章； 汪文川；

【作者基本信息】 北京化工大学 ， 化学工程， 1993， 博士

【摘要】 本文从两个方向开发了两个适用于聚合物溶液及液体的状态方程。其一是(?)现有的复杂空穴理论模型作合理的简化，提出了一个形式简单、精度较好的(?)用模型，以满足工程上的需要；其二是针对胞腔理论的缺点，提出“开放胞腔”的概念，建立了一个理论基础和精度更好的理论模型。本文用纯流体及混合物的实验数据广泛检验了这两个模型。结果表明，本文所建立的两个模型各有特点，是令人满意的。 Simha和Somcynsky提出的空穴理论状态方程(简称为SS EOS)，是目前可用于聚合物溶液和混合物模型中，理论基础和精度较好的一个。由于其被占座席分率无显函数表达式，形式较复杂，应用不便。本工作将不完全晶体中热缺陷的统计理论用于聚合物液体中，得到被占座席分率与对比温度的一个简单关系式，导出了简化的空穴理论状态方程(简称为SHT EOS)。本文进一步将该模型推广至大分子烃液体、有机溶剂及聚合物溶液和混合物中。用纯聚合物液体、大分子烃液体及有机溶剂的P-V-T实验数据、聚合物溶液和混合物的P-V-T数据、过量体积和过量焓数据、溶剂在聚合物中的活度及相行为等实验数据，对该模型进行了广泛检验。计算结果表明，该模型对各种性质的计算精度均较好且同SS EOS相当，但计算大为简化，是一个较好的实用模型。 本文进一步用基团贡献法对该模型中纯组分参数进行了处理，得到了14个基团的参数。此基团贡献模型可以预测正构烷烃、异构烷烃、环烷烃、芳香烃及部分聚合物的性质，为工程上的实际应用带来很大方便。 目前用于聚合物溶液的多数模型是建立在胞腔或自由体积概念上的(如著名的Flory方程和SS方程)。但胞腔概念实际上较适用于固体结构的描述，不能完全反映液体的结构特征。因此，在此基础上建立的模型不能很好地描述聚合物溶液和液体的性质。为了更加真实地反映液体的结构，本文提出了“开放胞腔”的概念。此时认为液体中所有胞腔都是“开放”的，处于胞腔中心的分子获得足够大的能量时可离开原来的胞腔而进入一个新的胞腔。这种结构更接近于液体的真实结构，且能较好地解释物质固、液、气三态的连续变化。 通过一系列的理论推导和数学处理，本文得到了开放胞腔自由体积的表达式，并导出了开放胞腔模型状态方程(简称为OCM EOS)。对前述的各种纯流体及混合物的各种性质的广泛检验表明，该模型较SS EOS改进较大，特别是与SS EOS等的半定量描述相比，本模型可得到相行为的定量表述。更多还原

【Abstract】 In this work two equations of state have been developed in two ways for polymer solutions and liquids. The first is to develop a simple practical model with good accuracy for chemical engineering needs by reasonably simplifying the existing complicated theoretical model. The second is to propose an "open-cell" concept and derive a model on better theoretical basis to overcome the defects of the cell theory. The two models have been extensively tested with experimental data for pure liquids and mixtures, in particular, for large molecules and polymers.The hole theory equation of state proposed by Simha and Somcynsky(SS EOS) is one of the models with good theoretical background and accuracy for polymer solutions and blends. However, the model is complicated and difficult to apply, because there is not an explicit expression for the occupied-site fraction. By applying the statistical theory for thermal defects of an imperfect crystal to polymer liquids, a simple relation between the occupied—site fraction and the reduced temperature has been derived and the SS EOS is simplified to a so called simplified hole theory equation of state (SHT EOS). The SHT EOS has been then extended to long chain hydrocarbon liquids, organic solvents and polymer solutions and blends tested with their experimental data, including P—V—T, the excess volume, the excess enthalpy, activity of solvents in polymers, and phase behavior. The results show that, the SHT EOS has the same quality as the SS EOS but with much less computing efforts.The molecular parameters for pure components in the SHT EOS have been treated by the group contribution method in this work. 14 group parameters have been obtained. Furthermore, the group contribution SHT EOS (GCSHT EOS) has been successfully used to predict the properties for n-paraffins, isoparaffins, cycloparaffins, aromatic hydrocarbons and some polymers which leads to great convenience in practical calculations.Currently, most existing models for polymer solutions are based on the concept of the cell or free volume (for example, the well— known Flory EOS and SS EOS). In practice, the cell concept stems from the solid structure, it is therefore unable to describe the features of liquids completely. Consequently, the models based on this concept can not be used to estimate the properties of polymer solutions and liquids with good accuracy. As a result, a new concept called "open— cell" is presented in this work. All the cells in liquids are assumed as "open" ones, and the molecule at the center of a cell can move out of the更多还原