Diamine coupling of maleic-anhydride-modified polyethylene

The efficiency of the diamines 1,12-diaminododecane (C12N2) and (4,4'-methylene)bis(2,6-diethylaniline) (MDEA) used as coupling agents for maleic-anhydride-grafted polyethylene (PEgMA) was compared. The effect of the miscibility of the diamines on the course of the reaction with PEgMA was investigated. The reaction in the molten state with the functional PE was run at 150 degreesC in an internal mixer and the resulting modified PE was characterized. The coupling agents reacted very fast, especially the aliphatic diamine. The MDEA was slower. Moreover, the reaction of the latter with the anhydride functions was not total owing to its immiscibility with PEgMA. With C12N2, the NH2-to-anhydride-function stoichiometry leading to the higher degree of coupling was 2, indicating that the imide ring was not formed at this temperature. In this case, the coupling of the PEgMA chains resulted in a highly branched structure characterized by a high viscosity of the molten polymer and a substantial insoluble PE-rich fraction. (C) 2005 Society of Chemical Industry.