A polymeric film or sheet comprising an ionomeric composition comprising ionomeric copolymer of an alpha olefin and about 1 to about 30 wt % of alpha,beta-ethylenically unsaturated carboxylic acid having 3 to 8 carbons, based on the total weight of the ionomeric copolymer, wherein the carboxylic acid is neutralized to a level of 1 to 100 mol %, with one or more metal ions, based on the total number of moles of carboxylate groups in the ionomeric copolymer, and wherein the ionomeric copolymer has a Melt Index of about 20 to about 300 g/10 min. The ionomeric composition preferably comprises an additive selected from the group consisting of silane coupling agent, organic peroxide, and combinations thereof. In addition, an article comprising an interlayer formed of the polymeric film or sheet and an additional layer selected from the group consisting of glass, other polymeric interlayer sheets, polymeric film layers, and metal films or sheets. Examples of articles include safety windows and solar cells.