Development of lignin‐based carbon foam for use as an FRP sandwich core material

Abstract Sandwich‐structure materials consist of a high‐strength skin material and a lightweight core material. The advantages of sandwich structures are known to include excellent mechanical properties and low weight, the latter of which is the result of a lightweight core. However, soft‐core members such as plastic foam materials have low rigidity and therefore may not exhibit adequate functionality when used in sandwich structures. This research sought to reduce environmental impact and to facilitate sustainable development by developing a method for fabricating high‐strength carbon foam using alkali lignin for use as an FRP sandwich core and enhancing the mechanical properties of the carbon foam with short glass fiber. PMMA particles decomposed at high temperatures to leave gaps, creating carbon foam with a closed structure. The relationship between PMMA particle size and foam pore size was investigated by observing cross‐sections of the foam.