IMIDIZATION REACTION PARAMETERS IN INERT MOLTEN POLYMERS FOR MICROMIXING TRACER STUDIES

A competitive-consecutive reaction involving a two-step imidization reaction in an inert molten polymer is proposed as a reaction tracer for studying micromixing viscous liquids in polymer processing geometries. In the proposed tracer system, phthalic anhydride reacts with p-phenylene diamine in molten polyethylene at dilute concentrations and elevated temperatures where the reactants and intermediates are soluble in the molten polymer. Rate constants were measured using a reactive film procedure and are reported in this paper over a range of temperatures. The rate constant for the first step was found to be an order-of-magnitude larger than the second step, and both steps were shown to be essentially irreversible. These conditions are used to show that the proposed reaction is mixing-sensitive and can be used to measure micromixing through measurements of selectivity.