Scalable method for bio-based solid foams that mimic wood

Abstract

Mimicking natural structures allows the exploitation of proven design concepts for advanced material solutions. Here, our inspiration comes from the anisotropic closed cell structure of wood. The bubbles in our fiber reinforced foam are elongated using temperature dependent viscosity of methylcellulose and constricted drying. The oriented structures lead to high yield stress in the primary direction; 64 times larger than compared to the cross direction. The closed cells of the foam also result in excellent thermal insulation. The proposed novel foam manufacturing process is trivial to up-scale from the laboratory trial scale towards production volumes on industrial scales.

Thermal gelation of cellulose based suspensions

“…However, recently more foams and aerogels have appeared with fully biobased ingredients and relevant functionalities. Such composite materials can be prepared from various fiber sizes ranging from macroscopic cellulose fibers (Reichler et al 2021) to nanocellulose fibers (Hu et al 2016;Lavoine and Bergström 2017;Kontturi et al 2018;Voisin et al 2018;Ee and Li 2021) and the applications are abundant. Depending on their properties they may find applications in packaging, electronics, medical scaffolds and ultra lightweight aerogels (Hjelt et al 2020).…”

“…After the foam reaches the desired shape, it should be rapidly heated to form the gel that will hold its shape during drying. This property was utilized in our previous studies (Reichler et al 2021;Miranda-Valdez et al 2023) where a nozzle extrudes parallel rods of liquid foam on a conveyor belt to dry under infrared lamps. The present article was prepared simultaneously with another research where the setup produces sheets of foam with a moving blade and the sheets then dry under hot air flow (manuscript under preparation by Ketoja et.…”

Wood compression in four-dimensional in situ tomography

“…Damage localization in materials under compressive loading leads to unpredictable behavior, which has in recent years an active area of research in theoretical [1][2][3], numerical [4] as well as experimental studies on e.g. rocks [5,6], porous materials [7], solid foams [8,9], and wood [10]. Compared to tensile failure, compression is particularly interesting as structures can carry load even after deforming [11] through frictional contacts.…”

Liquid Fraction Effect on Foam Flow through a Local Obstacle

“…Foam is a complex, two-phase medium behaving like a non-Newtonian fluid: at low applied stress, it exhibits elastic properties, and at a stress above a certain threshold value, it can flow like a viscous liquid [ 1 , 2 ]. Due to their specific properties, foams have a large range of applications from household, such as cosmetics and food, to industry, where it is used for the creation of various porous materials [ 3 ] or oil production [ 4 , 5 ]. In the latter case, the use of foams can significantly reduce the volume of water during hydraulic fracturing and minimize negative environmental impact.…”