New Jersey Center for Engineered Particulates and Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
New Jersey Center for Engineered Particulates and Department of Chemical and Materials Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
Eur J Pharm Biopharm. 2019 Apr;137:164-174. doi: 10.1016/j.ejpb.2019.02.023. Epub 2019 Feb 28.
Drying is an important unit operation in the manufacturing of polymer strip films as it affects various film quality attributes. Optimal design and control of convective drying process require models that capture the impact of critical process parameters such as air temperature and velocity on the temporal evolution of film thickness and moisture. Here, a detailed transport model was presented to capture moisture diffusion, heat transfer and moving boundary in convective drying of polymer strip films loaded with griseofulvin (GF), a poorly water-soluble drug. It incorporates a solvent diffusivity model based on free-volume theory. Experimentally, film precursor suspensions were prepared by mixing silica-coated and micronized GF powder with an aqueous solution of hydroxypropyl methylcellulose (HPMC)-glycerin. Films were cast and moisture-time variation during drying was measured. The transport model, whose diffusivity parameters were estimated using drying data at a reference condition, was validated at different drying conditions and wet film thicknesses. It delineates underlying mechanisms of drying kinetics and demarcates a smooth transition from constant-rate to falling-rate period. Overall, our results suggest that the transport model is capable of predicting the temporal evolution of moisture and final film thickness at different drying air velocities and temperatures with reasonable accuracy.
干燥是聚合物带状薄膜制造中的一个重要单元操作，因为它会影响各种薄膜质量属性。优化设计和控制对流干燥过程需要模型来捕捉关键工艺参数（如空气温度和速度）对薄膜厚度和水分随时间演变的影响。在这里，提出了一个详细的传输模型来捕捉含有灰黄霉素（一种水溶性差的药物）的聚合物带状薄膜在对流干燥过程中的水分扩散、传热和移动边界。它结合了基于自由体积理论的溶剂扩散模型。实验中，通过将涂覆有二氧化硅的灰黄霉素微粉与羟丙基甲基纤维素（HPMC）-甘油水溶液混合来制备薄膜前体悬浮液。然后浇铸薄膜并测量干燥过程中的水分随时间的变化。使用参考条件下的干燥数据来估计传输模型的扩散参数，然后在不同的干燥条件和湿膜厚度下对其进行验证。该模型描绘了干燥动力学的基本机制，并划定了从恒速期到降速期的平稳过渡。总的来说，我们的结果表明，该传输模型能够以合理的精度预测不同干燥空气速度和温度下的水分和最终薄膜厚度的随时间演变。
