Maleation of EPDM through reactive extrusion

An ethylene-propylene-diene rubber (EPDM) containing 5 wt% 5-ethylidene-2-norbornene was functionalized with maleic anhydride through the Alder Ene reaction at temperatures above 200 °C in a co-rotating twin screw extruder. Characterization of the maleated product included FT-IR, ¹H NMR, and GPC. The degree of functionalization was determined by infrared analysis and through increased mechanical properties arising from the formation of ionic crosslinks in the presence of zinc oxide. Increased temperature and maleic anhydride reactant concentration were found to improve the extent of reaction. Several Lewis acid species, i.e. SnCl2·2H2O, RuCln·xH2O and AlCl3, were found to behave as catalysts, having a minor effect, increasing succinyl content with reduced concentration.