Lightweight baffle or reinforcement element and method for producing such a lightweight baffle or reinforcement element

Disclosed is a baffle or reinforcement element (20) for sealing and/or reinforcing a cavity (C), in particular a cavity of a vehicle, comprising a carrier element (21) and an expandable element (25) supported by the carrier element, the expandable element consisting of an expandable material (22), incorporating a plurality of gas bubbles (24) forming a microcellular structure. Further disclosed is the process of manufacturing such a baffle or reinforcement element and its use.