Abstract
The residence time distributions (RTD) of a high shear twin screw extruder were measured by an on–line UV fluorescence device. First, by increasing throughput (Q) and screw speed (N), a decrease of the complex viscosity of the studied polypropylene (PP) was observed, revealing chain scissions. It was associated to high viscous dissipation taking place during extrusion, and more particularly under high shear conditions. Then the impact of these experimental conditions on the RTD was carried out. As expected, an increase of usual throughputs and screw speeds decrease mostly the RTD characteristic data. In this study industrial rate have been studied: throughput varied from 1.5 up to 22 kg h−1 and screw speed varied from 200 min−1 up to 1 200 min−1. However, by increasing the screw speed over usual values (from 500 up to 1 200 min−1), the variation of some experimental RTD characteristics were unexpected. Indeed, the slope of the shape of the experimental RTD function E(t) changed significantly. This phenomenon will be called lag or delay time. This result was only observed at low throughputs and high screw rotation speeds. To finish, a modeling software of twin screw extrusion process was used to compare experimental and calculated results. For usual processing conditions (up to 700 min−1), the simulation predicts nicely the experimental RTDs. However, at high screw speed (N > 800 min−1) and moderate throughput (Q = 4 kg h−1), the simulation fails to predict the RDT delay time. Hence, some side effects apparently occurred during high shear extrusion at low throughputs.
References
Arash, S. F., Martien, A., Hulsen, Han, E. H. M., Navid, M. H. F. and Patrick, D. A., “Tools to Simulate Distributive Mixing in Twin-Screw Extruder”, Macromol. Theory Sim., 21, 217–240 (2012) DOI: http://dx.doi.org/10.1002/mats.201100077Search in Google Scholar
Bigio, D. I., Elkouss, P., Wetzel, M. D. and Raghavan, S. R., “Influence of Polymer Viscoelasticity on the Residence Distributions of Extruders”, Aiche J., 52, 1451–1459 (2006) DOI: http://dx.doi.org/10.1002/aic.10754Search in Google Scholar
Bigio, D., Gao, J., Gregory, C., Briber, R. M. and Wetzel, M. D., “Residence-Time Distribution Model for Twin-Screw Extruders”, Aiche J., 45, 2541–2549 (1999) DOI: http://dx.doi.org/10.1002/aic.690451210Search in Google Scholar
Brandrup, J., Immergut, E. H.: Polymer Data Handbook, John Wiley & Sons, New York (1989)Search in Google Scholar
Cao, K., Li, Y., Lu, Z.-Q., Wu, S.-L., Chen, Z.-H., Yao, Z. and Huang, Z.-H., “Preparation and Characterization of High Melt Strength Polypropylene with Long Chain Branched Structure by the Ractive Extrusion Process”, J. Appl. Polym. Sci., 121, 3384–3392 (2011) DOI: http://dx.doi.org/10.1002/app.34007Search in Google Scholar
Cao, Y., Li, H., “Influence of Ultrasound on the Processing and Structure of Polypropylene during Extrusion”, Polym. Eng. Sci., 42, 1534–1540 (2002) DOI: http://dx.doi.org/10.1002/pen.11049Search in Google Scholar
Carneiro, O. S., Covas, J. A. and Vergnes, B., “Experimental and Theoretical Study of the Twin Screw Extrusion of Polypropylene”, J. Appl. Polym. Sci., 78, 1491–1430 (2000) DOI: http://dx.doi.org/10.1002/1097-4628(20001114)78:7<1419::AID-APP130>3.0.CO;2-BSearch in Google Scholar
Cassagnau, P., Bounor-Legaré, V. and Fenouillot, F., “Reactive Processing of Thermoplastic Polymers: A Review of the Fundamental Aspects”, Int. Polym. Proc., 22, 218–258 (2007)10.3139/217.2032Search in Google Scholar
Cassagnau, P., Mélis, F. and Bounor-Legare, V., “UV Fluorescence Monitoring of the Mixing of Molten Polymers in a Batch Mixer”, Polym. Eng. Sci., 43, 929–932 (2003) DOI: http://dx.doi.org/10.1002/pen.10076Search in Google Scholar
Cassagnau, P., Mijangos, C. and Michel, A., “An Ultraviolet Method for the Determination of the Residence Time Distribution in a Twin Screw Extruder”, Polym. Eng. Sci., 31, 772–778 (1991) DOI: http://dx.doi.org/10.1002/pen.760311103Search in Google Scholar
Da Costa, H. M., Ramosa, V. D. and De Oliveira, M. G., “Degradation of Polypropylene (PP) during Multiple Extrusions: Thermal Analysis, Mechanical Properties and Analysis of Variance”, Polym. Test., 26, 676–684 (2007) DOI: http://dx.doi.org/10.1016/j.polymertesting.2007.04.003Search in Google Scholar
David, J. C., Chalamet, Y., Taha, M., “Reactive Processing of Nonmisicble Polymers: Shear Rate Effect”, J. Appl. Polym. Sci., 92, 2357–2362 (2004) DOI: http://dx.doi.org/10.1002/app.13698Search in Google Scholar
De Loor, A., Cassagnau, P., Michel, A. and Vergnes, B., “Morphological Changes of a Polymer Blend into a Twin-Screw Extruder”, Int. Polym. Proc., 9, 211–218 (1994) DOI: http://dx.doi.org/10.3139/217.940211Search in Google Scholar
Fang, H., Mighri, F., Ajji, A., Cassagnau, P. and Elkoun, S., “Flow Behaviour in a Corotating Twin-Screw Extruder of Pure Polymers and Blends: Characterization by Fluorescence Monitoring Technique”, J. Appl. Polym. Sci., 120, 2304–2312 (2011) DOI: http://dx.doi.org/10.1002/app.33414Search in Google Scholar
Hu, G.-H., Kadri, I. and Picot, C., “One-Line Measurement of the Residence Time Distribution in Screw Extruders”, Polym. Eng. Sci., 39, 930–939 (1999) DOI: http://dx.doi.org/10.1002/pen.11482Search in Google Scholar
Kao, S. V., Allison, G. R., “Residence Time Distribution in a Twin Screw Extruder”, Polym. Eng. Sci., 24, 645–651 (1984) DOI: http://dx.doi.org/10.1002/pen.760240906Search in Google Scholar
Kohlgrüber, K.: Co-Rotationg Twin Screw Extruders Fundamentals, Technology, and Applications, Hanser, Munich (2007) DOI: http://dx.doi.org/10.3139/9783446433410Search in Google Scholar
Lertwimolnun, W., Vergnes, B., “Influence of Screw Profile and Extrusion Conditions on the Microstructure of Polypropylene/Organoclay Nanocomposites”, Polym. Eng. Sci., 47, 2100–2109 (2007) DOI: http://dx.doi.org/10.1002/pen.20934Search in Google Scholar
Li, Y., Shimizu, H., “Fabrication of Nanostructured Polycarbonate/Poly(methyl methacrylate) Blends with Improved Optical and Mechanical Poperties by High-Shear Processing”, Polym. Eng. Sci., 51, 1437–1445 (2011) DOI: http://dx.doi.org/10.1002/pen.21879Search in Google Scholar
Mack, C., Sathyanarayanal, S., Weiss, P., Mikonsaari, I., Hübner, C., Henning, F. and Elsner, P., “Twin–Screw Extrusion of Multi Walled Carbon Nanotubes Reinforced Polycarbonate Composites: Investigation of Electrical and Mechanical Properties”, IOP Conf. Ser.: Mater. Sci. Eng., 40, 1–10 (2012) DOI: http://dx.doi.org/10.1088/1757-899X/40/1/012020Search in Google Scholar
Methenni, A., Mighri, F., Elkoun, S., Fang, H. and Cassagnau, P., “Fluorescence Quentching of Fluoranthere by Maleic Anhydride in Solution and During Nonreactive and Reactive Twin-Screw Extrusion”, Polym. Eng. Sci., 53, 295–300 (2013) DOI: http://dx.doi.org/10.1002/pen.23263Search in Google Scholar
Michaeli, W., Greffenstein, A. and Berghaus, U., “Twin Screw Extrusion for Reactive Extrusion”, Polym. Eng. Sci., 35, 1485–1504 (1995) DOI: http://dx.doi.org/10.1002/pen.760351902Search in Google Scholar
Modesti, M., Lorenzetti, A., Bon, D. and Besco, S., “Thermal Behaviour of Compatibilised Polypropylene Nanocomposite: Effect of Processing Conditions”, Polym. Degrad. Stab., 91, 672–680 (2006) DOI: http://dx.doi.org/10.1016/j.polymdegradstab.2005.05.018Search in Google Scholar
Nietsch, T., Cassagnau, P. and Michel, A., “Melt Temperatures and Residence Times in an Extruder by Infrared Spectroscopy”, Int. Polym. Proc., 4, 307–315 (1997) DOI: http://dx.doi.org/10.3139/217.970307Search in Google Scholar
Oberlehner, Cassagnau P., and Michel, A., “Local Residence Time Distribution in a Twin Screw Extruder”, Chem. Eng. Sci., 49, 3897–39071 (1994) DOI: http://dx.doi.org/10.1016/0009-2509(94)00190-1Search in Google Scholar
Peterson, J. D., Vyazovkin, S. and Wight, C. A., “Kinetics of the Thermal and Thermo-Oxidative Degradation of Polystyrene, Polyethylene and Poly(propylene)”, Macr. Chem. Phys., 202, 775–784 (2001) DOI: http://dx.doi.org/10.1002/1521-3935(20010301)202:6<775::AID-MACP775>3.0.CO;2-GSearch in Google Scholar
Poulesquen, A., Vergnes, B., “A Study of Residence Time Distribution in a Co-Rotating Twin-Screw Extruders. Part I: Theoretical Modeling”, Polym. Eng. Sci., 43, 1841–1848 (2003) DOI: http://dx.doi.org/10.1002/pen.10156Search in Google Scholar
Poulesquen, A., Vergnes, B., Cassagnau, P., Michel, A., Carneiro, O. S. and Covas, J. A., “A Study of Residence Time Distribution in a Co-Rotating Twin-Screw Extruders. Part II: Experimental Validation”, Polym. Eng. Sci., 43, 1849–1862 (2003) DOI: http://dx.doi.org/10.1002/pen.10157Search in Google Scholar
Stivala, S. S., Reich, L., “Structure vs. Stability in Polymer Degradation”, Polym. Eng. Sci., 20, 654–661 (1980) DOI: http://dx.doi.org/10.1002/pen.760201003Search in Google Scholar
Teyssandier, F., Cassagnau, P., Gérard, J.-F., Mignard, N. and Mélis, F., “Morphology and Mechanical Properties of PA12/Plasticized Starch Blends Prepared by High-Shear Extrusion”, Mat. Chem. Phys., 133, 913–923 (2012) DOI: http://dx.doi.org/10.1016/j.matchemphys.2012.01.117Search in Google Scholar
Utracki, L. A., Shi, Z. H., “Development of Polymer Blend Morphology during Compounding in a Twin Screw Extruder. Part I: Droplet Dispersion and Coalescence – A Review”, Polym. Eng. Sci., 32, 1824–1833 (1992) DOI: http://dx.doi.org/10.1002/pen.760322405Search in Google Scholar
Vergnes, B., Della Valle, G. and Delamare, L., “A Global Computer Software for Polymer Flows in Corotating Twin Screw Extruders”, Polym. Eng. Sci., 38, 1781–1792 (1998) DOI: http://dx.doi.org/10.1002/pen.10348Search in Google Scholar
Wolf, D., Holin, N. and White, D. H., “Residence Time Distribution in a Commercial Twin-Screw Extruder”, Polym. Eng. Sci., 26, 640–646 (1986) DOI: http://dx.doi.org/10.1002/pen.760260910Search in Google Scholar
© 2014, Carl Hanser Verlag, Munich