A composition including at least two grafted copolymers, having a polyolefin trunk and polyamide grafts, the polyamide grafts being 15% to 25% by weight of the composition. Also, a multilayered structure including a plurality of adjacent layers, at least one of which has the above composition. The first grafted copolymer is a polyolefin backbone containing a residue of at least one unsaturated monomer (X) and a plurality of polyamide grafts, the polyamide grafts are attached to the polyolefin backbone by the residue of the unsaturated monomer (X). The second copolymer is a grafted elastomeric copolymer of a polyolefin backbone.