Multi-layered structure and a method of sealing or shaping using a multi-layered structure

A multi-layered structure comprising:

• an induction activation layer comprising a blend of
• (a) a first thermoplastic polymer;
• (b) a plurality of first particles, each said first particle comprising
• (i) a core comprising one or more magnetic materials and
• (ii) a shell comprising silicon dioxide;
• and
• (c) optionally a plurality of second particles, each said second particle comprising heat conducting particles;
• and
• a sealant, wherein the sealant exhibits a melting point equal to or lower than any other layer in the multi-layered structure;
• and
• a poor thermal conductive layer which comprises a thermoplastic polymer foam;
• wherein the induction activation layer and sealant are in direct or indirect thermal contact.