The document discusses the importance of rheology measurements for quality control in polymer processing. It states that viscosity is the most important parameter for processing molten polymers, and rheological measurements can detect subtle changes in material structure through measurements of flow behavior. Rheological tests provide fast and accurate methods for quality control across all aspects of polymer production and processing.

1. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Rheology - A Practical Approach To Quality Control A presentation to the Telford Polymer Association November 25th 2008

2. Why Rheology? The single most important parameter in the processing of a molten polymer is the viscosity function of the material – if it doesn't flow you can't process it! This parameter is highly sensitive to material structure. Rheological measurements can detect discrete changes in structure through flow behaviour, and can be fast & accurate methods of providing quality control for all aspects of the process. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

3. Why Rheology? The single most important parameter in the processing of a molten polymer is the viscosity function of the material – if it doesn't flow you can't process it! This parameter is highly sensitive to material structure. Rheological measurements can detect discrete changes in structure through flow behaviour, and can be fast & accurate methods of providing quality control for all aspects of the process. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Discriminating batch to batch variance Excellent in:

4. Why Rheology? The single most important parameter in the processing of a molten polymer is the viscosity function of the material – if it doesn't flow you can't process it! This parameter is highly sensitive to material structure. Rheological measurements can detect discrete changes in structure through flow behaviour, and can be fast & accurate methods of providing quality control for all aspects of the process. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Discriminating batch to batch variance ‘ Mapping’ processing problems Excellent in:

5. Why Rheology? The single most important parameter in the processing of a molten polymer is the viscosity function of the material – if it doesn't flow you can't process it! This parameter is highly sensitive to material structure. Rheological measurements can detect discrete changes in structure through flow behaviour, and can be fast & accurate methods of providing quality control for all aspects of the process. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Discriminating batch to batch variance ‘ Mapping’ processing problems Aiding failure analysis Excellent in:

6. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com ? Which Rheometer?

7. Melt Flow Indexer (Rate) Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

8. Brookfield Viscometer Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com ‘ LV’ ‘RV’ ‘HB’ Low Viscosity Medium Viscosity High Viscosity

9. Capillary Extrusion Rheometer Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

10. Controlled Stress / Rate Rotational Rheometer Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

11. Which Rheometer?? Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Rule of thumb: if structure sensitive measurements are required such as batch variance, melt stability, degradation studies, etc, then a rotational rheometer in oscillation mode. Investigations required at process-relevant shear rates call for the capillary rheometer.

12. Oscillatory Rheometry The oscillation technique involves applying a sinusoidal oscillating stress (  ) wave to the sample and measuring the resulting strain wave (  ). Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

13. Oscillatory Rheometry A purely elastic (Hookean solid) material will retain all of the deformation energy applied to it and will therefore have a phase difference (phase angle) of 0 degrees. Conversely, a purely viscous (Newtonian) fluid dissapates all of the applied energy and will have a phase angle of 90 degrees. Polymeric materials are Visco-elastic and as such their responses fall somewhere between these two extremes. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Hookean Solid Response Newtonian Fluid Response Visco-Elastic Response Phase Angle = 0 Phase Angle = 90 Phase Angle = 0<>90

14. Oscillatory Rheometry Measurements are normally made isothermally at constant strain amplitude, across a range of frequencies. A wealth of information relating to structural responses can be gained in oscillation mode. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

15. Oscillatory Rheometry Relationship of G’ / G” cross-over point to average molecular weight for HDPE. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

16. Oscillatory Rheometry Extremely accurate, reproducible results – calibrated instruments should give comparable data. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

17. Oscillatory Rheometry Simple ‘Go / No Go’ quality control programme set up for an automotive component manufacturer suffering from batch variance of incoming materials. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com Short Shot

18. Oscillatory Rheometry Invaluable in most failure analysis projects – oscillatory rheometry can usually give first indications of failure cause or at least point the investigation in the right direction. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com ‘ Good’ Component ‘ Failed’ Component

19. Oscillatory Rheometry Individual test programs can be run as a ‘macro’ to give tailored test profiles. Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com

20. www.gammadot.com For further information on rheological theory & measurement techniques check out the relevant sections on our website: Mark C. Edwards ● Gammadot Rheology Testing & Consultancy Services ● www.gammadot.com