Welle Frank
Fraunhofer Institute for Process Engineering and Packaging (IVV) Giggenhauser Straße 35, 85354 Freising, Germany.
Polymers (Basel). 2021 Apr 16;13(8):1317. doi: 10.3390/polym13081317.
General Purpose Polystyrene (GPPS) and High Impact Polystyrene (HIPS) is used in packaging food as well as for technical products. Knowledge of the diffusion behavior of organic molecules in polystyrene (PS) is important for the evaluation of the diffusion and migration process. Within this study, diffusion coefficients were determined in GPPS and HIPS below and above the glass transition temperature. Diffusion coefficients were determined from desorption kinetics into the gas phase using spiked GPPS and HIPS sheets as well as from permeation kinetics through a thin GPPS film. Overall, 187 diffusion coefficients were determined in GPPS and HIPS at temperatures between 0 °C and 115 °C. From the temperature dependency of the diffusion coefficients 45 activation energies of diffusion E and the pre-exponential factor D were determined. As expected, the activation energies of diffusion E show a strong dependency from the molecular volume of the investigated substances. At the glass transition temperature, only a slight change of the diffusion behavior were observed. Based on E and D, prediction parameters for diffusion coefficients were established.
通用聚苯乙烯（GPPS）和高抗冲聚苯乙烯（HIPS）用于食品包装以及技术产品。了解有机分子在聚苯乙烯（PS）中的扩散行为对于评估扩散和迁移过程很重要。在本研究中，测定了低于和高于玻璃化转变温度时GPPS和HIPS中的扩散系数。扩散系数通过使用加标GPPS和HIPS片材的解吸动力学以及通过薄GPPS膜的渗透动力学来确定。总体而言，在0°C至115°C的温度范围内，在GPPS和HIPS中测定了187个扩散系数。根据扩散系数的温度依赖性，确定了45个扩散活化能E和指前因子D。正如预期的那样，扩散活化能E显示出与所研究物质的分子体积有很强的依赖性。在玻璃化转变温度下，仅观察到扩散行为有轻微变化。基于E和D，建立了扩散系数的预测参数。
