Experimental Study of High Pressure Copolymer Solution Behavior

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The objective of this project is to investigate the role of segment-solvent and segment-cosolvent hydrogen bonding on the phase behavior of ethylene-based copolymer solutions. The approach used to reach this objective is to experimentally investigate the phase behavior of solutions which consist of polar/nonpolar, statistically random copolymers with polar and nonpolar solvents and cosolvents. The polarity and hydrogen bonding capabilities of the copolymers will be systematically varied by controlling the concentration of nonpolar and polar groups in the polymer backbone. The solvents will vary from the low-molecular-weight, nonpolar hydrocarbons to highly polar, hydrogen bonding hydrocarbons. Cosolvents such as dimethyl ether and ethanol will be used with the nonpolar solvents to determine the importance of hydrogen bonding and polarity on the phase behavior. Cloud-point curves and binary and ternary phase diagrams will be constructed at temperatures up to 448 K and at pressures up to 275 MPa--conditions which also bracket the free-radical polymerization process that is used for ethylene-based copolymers. The data will be modeled using the Sanchez-Lacombe equation of state in its present form and in a form revised to explicitly account for hydrogen bonding.