Ronald E Hazelton

US Patent:

49469401, Aug 7, 1990

Filed:

Aug 16, 1988

Appl. No.:

7/232713

Inventors:

Terry L. Guckes - Randolph NJ
Mark A. McHugh - South Bend IN
Charles Cozewith - Westfield NJ
Ronald L. Hazelton - Chatham NJ

Assignee:

Exxon Research and Engineering Company - Florham Park NJ

International Classification:

C08F 610

US Classification:

528483

Abstract:

A separation process has been found in which a polymer-solvent solution separates into phases of highly different composition which are in equilibrium over a broad temperature range. Upon addition of the phase separating agent, which is near or above its supercritical conditions, rapid disengagement into two phases occurs. The relative volume of solvent rich phase is substantially larger than the polymer rich phase. The process can be practiced at relatively low temperatures such as those employed in polymerization or post-polymerization processes. The separation is accomplished by adding or elevating the concentration of a phase separation agent to or above a minimum effective concentration, which causes the UCST and LCST lines to merge. Suitable phase separating agents are organic and inorganic compounds that are gases at 1 atm pressure and 25. degree. C. Due to the gaseous nature of the phase separating agent, it is easily removed from the solvent phase for reuse in the process.