| We investigated a polymer particle production method, termed Polymer Liquefaction Using Supercritical Solvation (PLUSS), in this thesis. In PLUSS, high pressure, low temperature CO2 liquefies the polymer due to melting or glass transition temperature depression, and solid particles are formed when the pressure is released.; An experimental and modeling study of PLUSS was conducted using the biodegradable polymer polycaprolactone (PCL). Spherical particles with an average size of 2--3 mum were made. We hypothesize that the particle shape is governed by the two-phase turbulent flow during the expansion, and that the particle properties are determined at the polymer freezing point. Based on these assumptions we established our PLUSS expansion modeling framework.; The characteristic features of the Tmelt vs. P curve---a linear regime at modest pressure, followed by an abrupt transition to a second regime where Tmelt changes little with P---were interpreted quantitatively in this thesis using the Clapeyron equation. (Abstract shortened by UMI.)... |
