Distinct extruder types are available to process material in an optimal way to meet your needs.
Single-screw extruders can be a cost-effective means of simple melting and shaping of an already mixed polymer blend. If distributive and dispersive mixing is necessary, twin-screw extruders are the instruments of choice.
For high-torque applications, the conical screw shape holds some advantages, but the flexible screw design of the co-rotating parallel twin-screw extruder makes it the prominent instrument in most of today’s material research laboratories.
Fundamentals of twin-screw compounding and scale-up
Curve showing scale-up
A variety of screw elements can be set up onto a hexagonal shaft to help ensure the plasticizing and homogenizing of materials fed into the extruder. Such elements can be configured to enable reactive extrusion, incorporate fillers and reinforce additives (e.g., glass fibers), or to allow degassing and venting of monomers.
Optimizing all relevant process parameters can be a challenge, but it is easier with a twin-screw compounder. Conducting a design of experiments (DoE) can be done in minimal time as the instrument doesn’t need to stop from one parameter change to another. Plus the recording of process data is easy, thus supporting experiment evaluation.
To apply a scientific scale-up approach from laboratory to production scale, the different size extruders need to have geometrical similarity. In addition, residence time and specific energy consumption of the process are also critical factors that should be kept constant when scaling up.
Twin-screw compounding: introduction and scale-up
Thermo Scientific EuroLab 16 XL Benchtop Twin-Screw Extruder
New functional polymers are continuously taking over applications in many industries. The compounding process is a decisive factor in ensuring that the properties of the new materials in development meet proper requirements. This webinar covers the principles of compounding based on examples from industry and the transfer from research and development to the production process (scale-up).
Scale-up of compounding processes
Thermo Scientific Process 11 Compact Lab Scale Extruder
To save development time and material when going from lab to line, a predictable scientific approach to scale-up can be used.
Key parameters to a successful scale-up are residence time distribution (RTD) and the consumption of specific energy in the process.
When you’re sure the different size extruders have geometrical similarity, then simply follow the approach outlined in our application note.