5. Conclusion

This article summarizes work on the distribution of residence times in extrusion processes over the period from 1970 to the present day. Although the peak of publications occurred around 2000, new interest in this subject has emerged in recent years, due to the development of hot melt extrusion (HME) and wet granulation for pharmaceutical applications.

Over the years, measurement techniques have evolved considerably. From the off-line techniques of the early days, we have gradually moved on to increasingly precise on-line measurements, enabling both global and local measurements to be taken by placing appropriate probes at different points along the barrel.

Although the main contributions of processing parameters to RTD are now well understood, some questions remain unanswered, such as the influence of rheological properties. Shear viscosity...