A self-sealing elastomer composition that includes a diene elastomer, a hydrocarbon resin with a given softening temperature, and a liquid plasticizing agent, is manufactured according to a process that includes successive stages. In one stage, the hydrocarbon resin is incorporated in the diene elastomer by kneading the resin and the elastomer in a mixer at or up to a temperature referred to as hot compounding temperature, which is greater than the softening temperature of the resin, in order to obtain a masterbatch. In another stage, the liquid plasticizing agent is incorporated in the masterbatch by kneading the agent and the masterbatch in the same mixer or in another mixer, in order to obtain the self-sealing composition. The self-sealing composition then is formed dimensionally.

Embodiments of an extruder comprise an extruder housing having an internal wall and a single screw coaxially disposed within the extruder housing, the single screw comprising a shank, wherein the shank and/or a region of the internal wall proximate the shank comprises helical channels. The extruder further comprises a feed channel downstream of the shank, and a visco-seal comprising the helical channels and the annular gap between the shank and the internal wall, wherein the annular gap is variable across its length.