Modification of ethylene/acrylate/carboxylic polymer

A process for increasing the hydrolytic stability and uniformity, and optionally increasing the molecular weight of random ethylene/methyl acrylate/1,4-butenedioic acid ester copolymer, said copolymer containing 0.5-10 weight percent 1,4-butenedioic acid ester, 40-62 weight percent methyl acrylate, and 28-59.5 weight percent ethylene, said process comprising heating said copolymer to a temperature of 140.degree.-200.degree. C. for a period of at least five minutes, and then contacting the heated copolymer in which the anhydride content is about 0.01-0.1 mole/kg of said heated copolymer with 0.01-0.1 equivalents of amine per kilogram of polymer wherein the amine consists of carbon, hydrogen and nitrogen atoms and is selected from the group consisting of monamines, polyamino compounds, compounds which generate such monoamines and polyamino compounds upon chemical reaction, and mixtures of the above.