A Particle Engineering Approach for the Design of Structured Microparticles

• Particle Engineering Design of Structured Microparticles

• Author / Creator

  Boraey, Mohammed A.

• The process of microparticle formation from evaporating microdroplets is the main production method for many products. For most of these applications (especially pharmaceutical ones) the properties and morphology of the final dry particle have to be precisely tailored to ensure the proper functionality of the final product. Particle engineering focuses on improving particle production processes by developing physical understanding and applying models to deliberately alter the properties of the particles. The present work discusses two aspects of the microparticle formation process, the evaporation rate and the transient concentration profiles. Although many other aspects are involved, it is thought that these two are the most influential ones. Chapter one gives a brief introduction to the process of structured microparticle formation along with the important particle physical properties and the associated challenges. Chapter two and three introduce a new particle formation theory for the formation of microparticles when diffusion is the main mechanism of mass transport. They also introduce a simplification of the theory results through a hybrid analytical/numerical model to ease the use of the results. Chapter four introduces a novel hybrid technique for calculation of the variable evaporation rate of microdroplets given knowledge of the droplet trajectory and the solvent material properties. A simplification of this approach is also proposed in the case when the trajectory data has a wide margin of uncertainty. In chapter five, the asymptotic state solution and the transient solution of the concentration profiles of an evaporating cylindrical cylinder were derived. These results are used to verify the new model proposed in chapters six and seven. Chapter six and seven propose a new numerical model (The Adaptive Interface Sweeping Method) for the calculation of the transient concentration profiles of an evaporating solution droplet. This model is capable of modeling many physical mechanisms involved in the particle formation process. It also offers a viable technique in dealing with variable material properties and evaporation rates. Chapter eight gives a brief discussion of the results introduced through the thesis and recommendations for future work.

• Subjects / Keywords

  • The Adaptive Interface Sweeping Method
  • Variable evaporation rate
  • Concentration profiles
  • Structured microparticles
  • Diffusion controlled microparticles formation
  • Particle Engineering

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R33F4KV3G

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.