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Faculty: Dr. M. Thompson
Associate Professor
Department of Chemical Engineering
McMaster Manufacturing Research Institute (MMRI) Member
Centre for Advanced Polymer Processing and Design
(CAPPA-D) Member
McMaster University
1280 Main Street West, Hamilton
Ontario, Canada L8S 4L7
Office: JHE-A411
email: mthomps@mcmaster.ca
voice: (905) 525-9140 ext.23213
B.Sc. McMaster University (1990),
B. Eng. McMaster University (1992),
M. Eng. McMaster University (1994),
Ph.D. University of Waterloo (1998).
The research interests of my group are primarily focused around extrusion
machinery, whether the process of study serves the plastics, pharmaceutical
or functional foods industries. Through
experiments and modeling, knowledge and software tools are being produced
to assist these
industrial sectors in controlling or developing their processes. We are
particularly interested in
controlling the morphology of an extruded material system in order to
achieve desired product specifications.
Current Areas of Research
- Granulation extrusion – particle design by wet or dry processes for pharmaceutical, nutriceutical, foods and
detergent applications. Tailoring of particle size/shape on a continuous
basis within an extruder through screw design and process layout.
- Composite processing – controlling structural
features within an extruder. Examination of interfacial and colloidal
properties for conventional and nano-scale fillers within a polymer
matrix. Understanding and modeling the relationship of morphology and
end-user specification in product design.
- Reactive modification – creating value-added
materials through chemical modification of a commodity species within
the extrusion environment. An extruder offers a modular environment
where each barrel section can provide a different temperature, pressure,
residence time, mixing intensity and concentration of reactant species
and thereby, can be seen as a multi-tank reactor system. Polymers and
foods are commonly modified by this approach.
- Foam extrusion – customization of polymer
products to exhibit reduced part weight, increased insulative properties,
reduced acoustical transmission, etc. We are interested in the manner
which a foaming agent can be introduced, rheological properties of the
gas-laden molten system during processing, and the relationship of cellular
structure to product features such as mechanical properties.
Recent Research Projects
1.Particple Processing Studies of Extrusion Processes
| Fig. 1: 3mm pellets entering a single-screw extruder | Fig. 2: Granulation of 0.1mm powder in a kneading element of a co-rotating twin screw extruder |
Particulate processing with screw extruders has been a vital industrial operation for decades. Plastics, food, and pharmaceutical industries rely on extruders to transform solids into more useable forms. Despite the importance of solids-related interactions within this machinery, little attention has been given to the granular mechanics taking place due to the difficulties in modeling such phenomena. Both design and troubleshooting activities on this class of machinery can be vastly improved if we can fully understand the whole process. The research conducted by my group is looking at the mechanisms of solids-conveying, melting, and granulation in extruders, both experimentally and with the use of numerical tools such as the “Distinct Element Method (DEM)”.
Select Publications: (Front Pages)
2. Polymer Processing
Experimental and simulation work looking at processing issues related
to extrusion (conventional, grooved, and twin-screw) and its many applications,
ex. sheet, pipe, wire/cable, compounding, and extrusion coating. We are
interested in understanding the root phenomena influencing important industrial
problems such as mix quality and process stability. Two areas of specific
interest are (a) foaming and (b) reactive modification of polymers. In
foaming, our group is examining processing aspect of foaming by physical
and chemical blowing agents and
how foaming may be utilized with composite materials like thermoplastic
olefin elastomers, glass-fiber
reinforced thermoplastics, and nanocomposites. In reactive modification
of polymers, the polymer processing equipment is used a solvent-less reactor
to change the molecular structure of the material. Unique chemistries
are employed in this high-temperature, high pressure environment to bring
about the desired
change in the molecular architecture of the polymer.
Selected Extrusion Publications:
“Experiments
and Flow Analysis of a Micropelletizing Die”, Polymer Engineering
and Science, 2004
“Mechanisms
for Mixing Powdered Filler into High-Density Polyethylene under Starve-Fed
Conditions in a Single-Screw Extruder”, Polymer Engineering and
Science, 2000
Select Publications on Foams and Reactive Modification:
“Functionalization
of Ethylene-Propylene Diene Terpolymer via the Alder Ene Reaction”,
Polym. Eng. Sci., 1998
“Terminal
Functionalization of Polypropylene via the Alder Ene Reaction”,
Polymer, 1998
3. Polymer Composites
We are interested in tailoring the properties of polymers to better meet the needs in more specialized applications. On-going projects in clay-polymer nanocomposites and electrically conductive materials have targeted usage to the automotive and alternative energy industries, attempting to show more economical methods of manufacturing or improved properties based on an understanding of transport phenomena and material properties.
4. Granulation Extrusion
Twin screw extrusion (TSE) is a relatively novel technology for the Pharmaceutical
and Nutraceutical industries, offering continuous processing capability
with superior mixing of particulate matter being granulated or wetted.
Our research currently examines the mechanisms involved in the granulation
or wetting of solid dosage products within a TSE. We are interested in
the impact of screw design and liquid injection strategies on controlling
particle size and liquid coating uniformity for typical materials used,
like lactose monohydrate or microcrystalline cellulose. Experimental and
numerical particle simulation approaches are being used to advance the
integration of extrusion technology into these industries.
Several projects are on-going
Selected Publications and Patents
J. P. Christiano, M. R. Thompson, "Extruder Screw", Davis-Standard
Corporation, US
Patent No. 6, 179,461 (Jan. 30, 2001).
G. Zhang, M. R. Thompson, “Reduced Fiber Breakage in an Injection
Molding Machine”,
Annual Technical Meeting for the Society of Plastics Engineers (ANTEC),
May 2005
C. Xi, E. Takacs, M. Tate, M. Thompson, J. Vlachopoulos, “Study
of the Micropelletization Process”,
Annual Technical Meeting for the Society of Plastics Engineers (ANTEC),
61, 278-282 (2003).
M.R. Thompson, J. P. Christiano, “Analysis of Feed Characteristics
on the Performance of
Groove-Feed Extruders”, ANTEC, 59, 190-194 (2001)
K. R. Slusarz, M. R. Thompson, J. P. Christiano, “An Experimental
Comparison of the
Improved Mixing Obtained from a New Barrier Screw Design”, ANTEC,
59, 262-266 (2001)
J. P. Christiano, M. R. Thompson, “A New Barrier Screw Design Utilizing
Solid Bed
Deformation with Forced Melt Removal”, ANTEC, 58, 78-82 (2000)
M .R. Thompson, J. P. Christiano, “Investigation of the Melting
Mechanism within a Groove-Feed
Single-Screw Extruder”, ANTEC, 58, 129-133 (2000)