Developments in the synthesis of maleated polyolefins by reactive extrusion

The maleation of conventional and metallocene linear low density polyethylenes by reactive extrusion has been explored with a view to defining the conditions necessary for a robust process that provides both high grafting efficiencies (>80%) and minimal degradation or cross-linking. The dependence of grafting efficiency on various operating parameters (maleic anhydride level, maleic anhydride:initiator ratio, throughput rate, direction of screw rotation, temperature) has been established. Literature methods for characterization of the grafted product based on FTIR or ¹H NMR analysis have been critically examined with respect to their ability to distinguish between single unit and oligomeric maleic anhydride grafts and found to yield ambiguous results.