In-process rheometry as a PAT tool for hot melt extrusion.
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Citations
Coupling hot melt extrusion and fused deposition modeling: Critical properties for successful performance.
An update on the contribution of hot-melt extrusion technology to novel drug delivery in the twenty-first century: part I
Hot-melt extrusion: Highlighting recent advances in pharmaceutical applications
Rheology by Design: A Regulatory Tutorial for Analytical Method Validation.
Specific mechanical energy - An essential parameter in the processing of amorphous solid dispersions.
References
A multiple-step slit die rheometer for rheological characterization of extruded starch melts
A novel tool to standardize rheology testing of molten polymers for pharmaceutical applications.
Rheological study of the mixture of acetaminophen and polyethylene oxide for hot-melt extrusion application.
A novel transflectance near infrared spectroscopy technique for monitoring hot melt extrusion.
Shear Stress at Wall and Mean Normal Stress Difference in Capillary Flow of Polymer Melts
Related Papers (5)
Frequently Asked Questions (13)
Q2. What is the effect of temperature on the viscosity of polymer molecules?
Increasing temperature provides the polymer molecules with greater mobility allowing them to flow more freely whereas plasticizers act to reduce the internal resistance of the polymer melt by effectively lubricating the flow of polymeric chains.
Q3. What can be used to give an indication of specific energy input to the melt?
Motor torque and material throughput can also be recorded and used to give an indication of specific energy input to the melt, which is related to the temperature, material properties and degree of filling in the extruder screw channels.
Q4. How long was the rheological die allowed to stabilize?
At each set throughput, the process was allowed a 15 minute stabilization period before pressure measurements were recorded, for a representative period of around 10 minutes.
Q5. What is the use of a slit die rheometer?
In-line rheological slit dies have also been used in twin screw extrusion, both for monitoring reactive extrusion processes such as cross-linking of polyethylene 29 and for incorporation of additives such as the flame retardant magnesium hydroxide into a polyethylene 30 .
Q6. How many Hz were used to measure the pressure of the slit die?
Three pressure transducers (Dynisco PT435) with a full scale deflection of 10.3 MPa were flush mounted at the surface of the slit and monitored at a frequency of 1
Q7. How can rheology be measured in a die?
Real-time assessment of rheology within the extrusion process can be achieved by measurement of pressure drop inside an instrumented extruder die.
Q8. What is the effect of the API loading on the die?
Results showed that the compound displayed shear thinning behavior in the mixtures tested and that shear viscosity decreased with increase in API loading, reflecting miscibility of the API within the polymer matrix.
Q9. How much shear strain was observed at 40 % w/w API?
The plasticization effect of the API was also clearly observed, with shear viscosity decreasing from 1150 Pa.s at 20 % w/w API to 233 Pa.s at 40 % w/w API at an apparent shear strain rate of 15 s -1 .
Q10. What can be used as a quality control indicator?
Such measurements can be used as a quality control indicator, using statistical process control and trending analysis to detect deviations from the desired set point.
Q11. How many studies have been reported on the use of rheology?
Rheology has been used to characterize pharmaceutical solid dispersions and solutions, although only a relatively small number of studies have been reported.
Q12. What is the effect of high temperature and mixing on the flow properties of the polymer?
It appears likely that this exposure to high temperature and mixing had an effect on the consistency of the flow properties of the compound, increasing the level of plasticization and mixing.
Q13. What was the result of the rheological analysis of the API?
This indicated that the API was readily miscible within the polymer matrix in the molten state, and that the API had a plasticising effect.