A process for producing an ethylene copolymer, the process including: (a) contacting ethylene with at least one polar comonomer in the presence of at least one modifier and at least one free radical initiator in a tubular reactor under polymerization conditions including a pressure of from 225 to 270 MPa; (b) injecting the at least one free radical initiator into the reactor at a plurality of reaction zones spaced along the length of the reactor, wherein each reaction zone comprises an inlet and an outlet; (c) maintaining the temperature at the inlet of each reaction zone at 150° C. or less, and the temperature at the outlet of each reaction zone is at least 177° C.; (d) controlling the modifier flow at a rate of from 0.02 to 0.986 wt % of the copolymer; and (e) recovering the ethylene copolymer from the tubular reactor, is provided.