the present invention relates to a composition that comprises a mixture of polymers , which comprises : a first polymer comprising polyphenylene sulphide , making up 55 wt % to 95 wt % of the mixture ; a thermoplastic modifier , making up 5 wt % to 45 wt % of the mixture ; optionally one or more functional additives , making up at most 10 wt % of the mixture , preferably at most 5 wt % of the mixture , characterised in that the thermoplastic modifier includes a second polymer which comprises a polyolefin backbone containing a group of at least one unsaturated monomer and a plurality of polyamide grafts . the invention also relates to a multilayer structure including a plurality of adjacent layers , at least one of which consists of the aforementioned composition .