Recyclable and curved sandwich composites through bendable benzoxazine-based foaming core

Patent details


European patent filed

Priority date

11 July 2022


De-Yi Wang, Xuebao Lin


IMDEA Materials Institute

Transfer opportunity

License of technology


IMDEA Materials has developed a vitrimer-based syntactic foam with application in recyclable and curved lightweight sandwich composites manufactured by hot-press, for flexible interiors in the transportation, aerospace and defense industries, as well as in construction.


One of the most important trends in the lightweight composites industry is the low-cost and low-energy consumption of out-of-autoclave processes of sandwich composites and recycle or reuse of high-value raw materials. Especially for large-scale products with complex curved shapes, it is still a big challenge to assemble the rigid foaming core before processing. Therefore, the lightweight composites industry demands novel rigid foaming cores that are shapeable, recyclable and easy to process. Meanwhile, all the mechanical properties and functions of the lightweight sandwich composites, such as flame retardancy, thermal insulation and sound insulation, still need to meet the specific requirements of the industrial applications.

IMDEA Materials has developed a methodology to synthesize recyclable and bendable foaming cores to manufacture recyclable lightweight sandwich composites that can be used as different structural parts and interior parts in the transport sector and also in construction. 

The resulting recyclable lightweight sandwich compositions display improved mechanical properties, fire resistance, curved shape ability and out-of-autoclave processing.

Advantages and innovations

  • The composite presents low density and well deformability and recyclability which are critical for preparing reusable curved shape sandwich composites.
  • It has good thermal properties and it is easy to compound with CFRP panels by out-of autoclave processes.
  • It is a good flame retardant and provides thermal and sound insulation, which are critical functions for the interior materials of automotive, rail and aircraft vehicles.
  • These composites can combine densities between 120-250 g/m3, compressive strength of 0.8-2 MPa, heat resistance between 80-150ºC, thermal conductivity of 0.04-0.08 W/m.k. and V-0 flame retardancy level.


Knowledge & Technology Transfer Department, IMDEA Materials Institute


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