Computational thermodynamics of multicomponent compressible polymer solutions

点击翻译按钮获取中文摘要

Production of polyolefins using solution polymerization methods takes place at high pressure and results in a multicomponent polymer solution reactor effluent. Comodity polymers , such as polyethylene, are produced using solution polymerization methods under high pressure and temperature. During the downstream heat processing stage , changes in operating conditions lead to phase separation and the emergence of different phases containing different polymer compositions as well as a complex morphology. The complex multiphase morphology in turn affects the heat transfer process in the heater unit, leading to changes in heater efficiency and pressure drops through the course of the heater. This phase separation may occur to such a degree that phase inversion occurs. The phase separation of this multiphase-multicomponent flowing stream is dictated by instabilities, such as spinodal decomposition, that seek to reduce the energy of the system. The polymer is fractionated between the liquid phases, yielding different polymer molecular weight distribution curves and attendant physical properties. To optimize the design and control of these heating units a better fundamental knowledge of the thermodynamic principles that govern phase separation in compressible multicomponent polymer solutions are required. This proposal presents a research program that integrates polymer molecular thermodynamics, mathematical process modeling, and high performance computing to accurately predict the thermodynamics and interfacial properties of polyethylene ternary solutions, and the kinetics of phase separation of compressible polymer solutions under condition relevant to polyolefin manufacturing based on solution polymerization methods.