Institute of Pharmaceutics and Biopharmaceutics, Heinrich-Heine-University, Düsseldorf, Germany.
Eur J Pharm Biopharm. 2013 Nov;85(3 Pt B):1200-5. doi: 10.1016/j.ejpb.2013.07.019. Epub 2013 Aug 7.
The hot melt extrusion process is a widespread technique to mix viscous melts. The residence time of material in the process frequently determines the product properties. An experimental setup and a corresponding mathematical model were developed to evaluate residence time and residence time distribution in twin screw extrusion processes. The extrusion process was modeled as the convolution of a mass transport process described by a Gaussian probability function, and a mixing process represented by an exponential function. The residence time of the extrusion process was determined by introducing a tracer at the extruder inlet and measuring the tracer concentration at the die. These concentrations were fitted to the residence time model, and an adequate correlation was found. Different parameters were derived to characterize the extrusion process including the dead time, the apparent mixing volume, and a transport related axial mixing. A 2(3) design of experiments was performed to evaluate the effect of powder feed rate, screw speed, and melt viscosity of the material on the residence time. All three parameters affect the residence time of material in the extruder. In conclusion, a residence time model was developed to interpret experimental data and to get insights into the hot melt extrusion process.
热熔挤出工艺是一种广泛应用于混合粘性熔体的技术。物料在该工艺中的停留时间通常决定了产品的性能。本文开发了一种实验装置和相应的数学模型，以评估双螺杆挤出过程中的停留时间和停留时间分布。挤出过程被建模为由高斯概率函数描述的质量传递过程和由指数函数表示的混合过程的卷积。通过在挤出机入口处引入示踪剂并在模具处测量示踪剂浓度来确定挤出过程的停留时间。这些浓度与停留时间模型拟合，发现了一个合适的相关性。得出了不同的参数来描述挤出过程，包括死区时间、表观混合体积和与传输相关的轴向混合。进行了 2(3) 设计实验以评估粉末进料速率、螺杆转速和材料熔体粘度对停留时间的影响。这三个参数都影响了物料在挤出机中的停留时间。总之，开发了一个停留时间模型来解释实验数据并深入了解热熔挤出过程。
