Peroxide-catalyzed grafting of maleic anhydride onto molten polyethylene in the presence of polar organic compounds

The crosslinking of LDPE resulting from reaction with dicumyl peroxide at 180°C is increased in the presence of maleic anhydride (MAH). The presence of electron‐donating nitrogen‐containing compounds (amides, lactams, disubstituted aromatic amines, and amine oxides), phosphorous‐containing compounds (phosphites, phosphates, phosphonates, phosphoramides, and phosphine oxides) and sulfur‐containing compounds (sulfoxides, aryl disulfides, and thiazyl disulfides) which inhibit the homopolymerization of MAH but not that of methyl methacrylate, prevents crosslinking and yields soluble PE containing MAH units. Crosslinking, due to coupling of PE˙ macroradicals formed by hydrogen ion from PE by excited MAH, is prevented by electron donation from the additive to the MAH+ cation which is present in the MAH+−MAH excimer as well as in the excimer which is appended to the PE.