Skip to main content

Dr. Michael Thompson

Associate Dean (Graduate Studies)

Department of Chemical Engineering

Expertise:
polymer processing, extrusion and reactive extrusion.
Areas of Specialization:
Research Clusters:
Email:
Office:
JHE A411
Phone:
+1 905.525.9140 x 23213

Overview

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/porosity on a continuous basis within an extruder through screw design and process layout. Current work includes studying the mechanisms involved in wet granulation within the extruder when using liquid injection or foam delivery methods. Additionally, melt granulation is being studied for its capacity to improve the storage and bioavailability of moisture-sensitive or highly hydrophobic APIs, showing this method is often a desirable alternative to hot melt extrusion techniques.
  • Spray drying– encapsulating of biologically active ingredients in appropriate diluents for aerosol delivery forms. (new)
  • Passive Acoustic Emissions Analysis – Detection of ultrasonic frequencies emitted by materials during interface separate, changes in crystallinity or while microcracking. The technique has the advantage of detecting change well before other analyses can reveal information. Used to monitor the service life of materials in their environment but also how to improve a material or composite formulation.
  • Composite/Bioplastics processing – controlling structural features within an extruder. Examination of interfacial and colloidal properties for conventional and nano-scale fillers within a polymer matrix of synthetic or biological origins. Understanding and modeling the relationship of morphology and end-user specification inproduct design
  • Gas-polymer and liquid-polymer dispersive extrusion – customization of polymer products in continuous or discrete forms to exhibit important features as end properties. This includes preparation of foams but may alternatively use the non-polymer phase to create a beneficial morphology within the polymer.

Recent Research Projects

1. Granulation Extrusion

Twin screw extrusion (TSE) is a relatively novel technology for the Pharmaceutical and Nutraceutical industries, offering continuous manufacturing capability with superior mixing of particulate matter being granulated or wetted. Our research examines:

  • Foam granulation – this robust, continuous manufacturing technology using a twin screw extruder was developed by our group in collaboration with the original co-inventor (Paul Sheskey, Dow Chemical) to consider aqueous foam as a binder.
  • Wet granulation – studying the influence of process, material and screw design factors on granule development, using liquid injection or foam delivery methods.
  • Melt granulation – use of a molten binder to granulate excipients without the use of water.

Experimental studies and numerical particle simulation approaches are being used to advance the integration of extrusion technology into these industries.

Select publications of previous work (front pages):
"Understanding wet granulation in the kneading block of twin screw extruders". Chemical Engineering Science, March 2014
"Examining the mechanics of granulation with a hot melt binder in a twin-screw extruder", Chemical Engineering Science, 2012
"Foam granulation: new developments in pharmaceutical solid oral dosage forms using twin screw extrusion machinery", Drug Development and Industrial     Pharmacy, 2012
"Wet Granulation in a Twin-Screw Extruder: Implications of Screw Design", Journal of Pharmaceutical Sciences, 2010

2. Passive Acoustic Emissions

We are interested in the high frequencies, 50-500kHz, signals emitted by materials under stress.  Current projects are looking at the effect of fluids on polymets in service to detect environmental damage and the use of acoustics to fine-tune the interfacial properties between the fillers and matric of a sheet molded composite (SMC)

Select publications of previous work (front pages):

  • Evaluating the influence of contacting fluids on polyethylene using acoustic emissions analysis" Polymer Testing, online August 2014

 3. Solvent Free Extrusion Emulsification

 There are many polymers that can not be grown by polymerization as an emulsion due to their water sensitivity. There is also often a desire to make an emulsion where the polymer particles contain other ingredients such as a drug, pesticide, etc.  Solvent emulsification is the current route to synthesis in such cases but the solvent is costly, its recovery is expensive, the precipitation process is long and the purity of the polymer product is always in question.  We are working to understand a new technique where a polymer melt that was plasticized inside a twin screw extruder can be converted into nanosized (~100nm) particles suspended in an aqueous solution, never touching solvents during the process.

 

Select publications of previous work (front pages):

  •   "Morphological Development of Latex Particles in a solvent-Free Extrusion Process", Society of Plastics Engineers Annual Technical conference, Las Vegas, NV (2014)

  4. Particle 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 modelling 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)

  • "Investigation of Solids Transport in a Single-Screw Extruder Using a 3-D Discrete Particle Simulation", Polymer Engineering and Science, 2004
  • "Modelling the solids inflow and solids conveying of single-screw extruders using the discrete element method" Powder Technology, 2005
  • "Determining the collision properties of semi-crystalline and amorphous thermoplastics for DEM simulations of solids transport in an extruder" Chemical Engineering. Science, 2007

5. Bioplastics, Foams and Reactive Modifications

We are interested in understanding the root phenomena influencing important industrial problems such as product quality and process stability which arise as special materials are being prepared by extrusion. Bioplastics are a new category of polymers which present benefits to industries where single-use applications are dominant and low mechanical strength can be tolerated, like the packaging sector. As a new material class, these bioplastics often require very different machinery configurations and processing practices be used compared to petroleum plastics. 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 to do more than simply reduce part weight, like control fiber orientation. In reactive modification of polymers, the polymer processing equipment is used as a solvent-less reactor to change the molecular architecture of a 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 Bioplastics publications

  • "Biocomposites reinforced with cellulose nanocrystals derived from potato peel waste", Carbohydrate Polymers, 2012
  • "In situ kinetic study of solid-state crosslinking of potato starch", Starch, 2011
  • "The effect of pea fiber and potato pulp on thermal property, surface tension, and hydrophilicity of extruded starch thermoplastics", Carbohydrate Polymers, 2011

 

Selected publications on Foams and Reactive Modification/Degradation

  • Evaluating different Alkyl Ammonium Modified Organoclays in Preparation of TPO Nanocomposites with Supercritical CO2", Polymer composites, 2014
  • "Supercritical CO2 as an Exfoliating Aid for Nanocomposite Preparation: Comparison of Different Processing Methodologies", Polymer Engineering and Science, 2012
  • "Multiple Percolation in a Carbon-Filled Polymer Composites via Foaming", Journal of Applied Polymer Science, 2010
  • "Reduced fibre breakage in a glass-fibre reinforced thermoplastic through foaming", Composites Science and Technology, 2005

 

6. 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.

  • "Properties of a Carbon Filled Cyclic Olefin Copolymer", Journal of Polymer Science: Part B-Polymer Physics., 2007
  • "Recyclability of a layered silicate-thermoplastic olefin elastomer nanocomposite", Polymer Degradation and Stability, 2006

Education

  • B.Sc. McMaster University (1990)
  • B. Eng. McMaster University (1992)
  • M. Eng. McMaster University (1994)
  • Ph.D. University of Waterloo (1998)

Publications

Recent

  • J. P. Christiano, M. R. Thompson, "Extruder Screw", Davis-Standard Corporation, US Patent No. 6, 179,461 (Jan. 30, 2001).
  • M. R. Thompson, Twin Screw Extrusion for the Granulation of Pharmaceuticals, Annual Technical Meeting for the Society of Plastics Engineers (ANTEC), Cincinnati, OH. Apr 22-24 (2013)
  • J-M. Restreop-Florez, A. Bassi, M. Thompson, Effect of Biodiesel Addition on Microbial Population in Diesel Storage Tanks, NACE International Corrosion Conference and Expo, 2013.
  • M. R. Thompson, S. Weatherley, R. Pukadyil, B. Mu, P. J. Sheskey, Foam Granulation Extrusion: A Novel Method to Continuous Wet Granulation of Powder Drug Formulations, American Institute of Chemical Engineers (AICHE) Annual Conference, Pittsburgh, PA, Oct. 28-Nov. 2 (2012)
  • P. J. Sheskey, B. Mu, M. R. Thompson, Aspects of Foamed Binder Addition for Foam Granulation in a Twin Screw Extruder, American Association of Pharmaceutical Scientists General Meeting, Chicago IL, Oct 14-18 (2012)
  • M.R. Thompson, S. Weatherley, R.N Pukadyil, and P.J. Sheskey, Foam Granulation Extrusion: A Novel Method to Continuous Wet Granulation of Powder Drug Formulations, American Association of Pharmaceutical Scientists General Meeting, Washington DC, Oct 23-25 (2011)
  • M. Mazhary, K.E. Nielsen, F.A. Brandys, M.R. Thompson, Understanding thermally induced wrinkling in decorative film laminated sheets, Annual Technical Meeting for the Society of Plastics Engineers (ANTEC), Boston, MA. May 1-5 (2011)
  • J. Liu, W.R. Rodgers, T. Cao, M.R. Thompson, Exfoliation aids for preparation of polymer-layered silicate nanocomposites, Annual Technical Meeting for the Society of Plastics Engineers (ANTEC), Boston, MA. May 1-5 (2011)