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首页> 外文期刊>RSC Advances >Determination of concentration-dependent diffusion coefficient of seven solvents in polystyrene systems using FTIR-ATR technique: experimental and mathematical studies
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Determination of concentration-dependent diffusion coefficient of seven solvents in polystyrene systems using FTIR-ATR technique: experimental and mathematical studies

机译：使用FTIR-ATR技术测定聚苯乙烯系统中七溶剂的浓度依赖性扩散系数：实验和数学研究

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In the present study a new mathematical model's outcome based on experimental data is considered to determine the diffusion coefficients in polystyrene/solvent systems as a function of solvent concentration. We used a calibrated Fourier transform infrared attenuated total reflectance (FTIR-ATR) instrument to collect the spectra from a thin layer of polymer solution covered optically dense ZnSe crystal. The collected spectra were transferred to the components' concentration, using principal component regression analysis, representing the compositional change of the polymer solution during the time. Two approaches were employed to obtain the diffusion coefficients of seven solvents in polystyrene solutions: first, we considered whole range of polymer concentration to obtain the diffusion coefficient by fitting the diffusion model on experimental data. In the second approach only early stage of evaporation process was figured, considering vitrification phenomenon in the upper layers of polymer solution film. For all solvents, higher values of diffusion coefficients obtained using second approach, showing a satisfying agreement with the literature. As a concluding remark, vitrification is an important event taken place during mass transfer processes in which it should be considered to find a reliable value for diffusion coefficient.
机译：在本研究中，基于实验数据的新数学模型的结果被认为是根据溶剂浓度的函数确定聚苯乙烯/溶剂系统中的扩散系数。我们使用了校准的傅立叶变换红外衰减总反射率（FTIR-ATR）仪器，从聚合物溶液薄层覆盖光学致密的ZnSe晶体中收集光谱。使用主成分回归分析，将收集的光谱转移至组分的浓度，表示在该时间内聚合物溶液的组成变化。采用两种方法在聚苯乙烯溶液中获得七溶剂的扩散系数：首先，我们认为全系列聚合物浓度，以通过在实验数据上拟合扩散模型来获得扩散系数。在第二种方法中，考虑到聚合物溶液膜的上层中的玻璃化现象，仅考虑蒸发过程的早期阶段。对于所有溶剂，使用第二种方法获得的扩散系数的较高值，显示与文献的令人满意的协议。作为结论性的评论，玻璃化是在大规模转移过程中进行的重要事件，其中应该考虑找到可靠的扩散系数值。

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