There're three types of core materials used as sandwich structure of FRP products: rigid foam, honeycomb and balsa wood.
Rigid foam includes PVC foam, PU foam , PMI foam, PEI foam, PET foam ect.
The honeycomb sandwich structure has high strength and good rigidity, but the honeycomb has an open-cell structure, and the bonding area with the upper and lower panels is small, and the bonding effect is generally not good.
Balsa wood is mainly produced in plantations in South America. Due to climatic reasons, balsa wood grows particularly fast in the local area, so it is much lighter than ordinary wood, and its fiber has good strength and toughness, especially suitable for composite interlayers structure.
Main applications of core materials are aerospace, boat, wind energy, buildings.