Thermally expandable composition

The present application relates to a thermally expandable composition comprising at least a peroxide cross-linking polymer which does not glycidyl (meth) acrylate in copolymerized form as monomer, at least one polymer in a proportion of 2 to 20 wt .-%, based on the respective polymer , glycidyl (meth) acrylate in copolymerized form as monomer, at least one peroxide and at least one endothermic chemical blowing agent contains ,, moldings which contain this composition, and a method for sealing and filling of cavities in components for reinforcing or stiffening elements, in particular hollow members, and for the bonding of mobile devices using such shaped bodies.