An excerpt of the final research course of nanotechnology and functional materials for design – Politecnico di Milano, by Sabina Veronica Fontanarosa, Silvia Maria Gauri, Elena Galvez, Anna De Mezzo
Liquid wood is a biopolymer thermoplastic composite that is manufactured from substances derived from wood. A material that is still little known however as a valid substitute for thermoplastic polymers with high environmental impact.
In our research we wanted to deepen knowledge about the liquid wood composition, classification, technical characteristics, physical and perceptual, investigating the various meanings of the name “liquid wood” and related materials.
In a second part of the study we analyzed the current uses of this material, the products thus far and the companies that are experiencing, a key time to understand what is expected of this material and what will be its future.
Liquid wood is a bioplastic composite obtained from three natural ingredients: lignin, cellulose and flax, hemp or other plants, adding natural additives.
This material was developed by the German company TECNARO, in cooperation with the Fraunhofer Institute for Chemical Technology. The trade name with which the material is produced by TECNARO is ARBOFORM or ARBOBLEND: itself suggests the nature (from Latin arbor, that means tree).
Liquid wood is characterized by composition, color and smell similar to wood, and it has mechanical and physical properties which are situated, as values, among those of wood, traditional composites and polymers; finally, it can be processed as a thermoplastic polymer, feature from which the name “liquid” comes.
The definition of this material combines the concepts of biopolymer, composite and natural materials engineered wood.
As biopolymer, it takes part of the “biobased polymer“, i.e. polymers based on renewable raw materials; in this case it is retrieved from natural material, and is 100% biodegradable. The classification as composite comes from coexistence in material of a continuous phase, composed of lignin and cellulose, and dispersed, or vegetable fibers.
As far as concerns the substances from which the material comes, these are the same that make up wood: lignin and cellulose, with the addition of flax or hemp fibers and natural additives. In fact any type of wood consists of three natural polymeric substances: cellulose (about 45%) lignin (approximately 23%) and hemicelluloses (about 30%).
Cellulose and hemicellulose are the fibers, whereas lignin is the inter-fiber that holds them together. Cellulose is one of the most important polysaccharides, lignin is a heavy and complex organic polymer consisting mainly of phenolic compounds. Except of polisacccaridi, lignin is the most abundant organic polymer in the plant world.
As the name implies, this is the substance that makes woody plants and that has the function of keeping together the more or less branched chains of hemicellulose, helping the Organization into fibrils. In this way it gives firmness and resistance to the plant.
Lignin is also known as material as the encrusting fibers. To extract the cellulose, lignin is therefore first attacked and dissolved to separate the olocellulosa, from where the cellulose and hemicellulose is extracted then.
ARBOFORM inherits some characteristics from wood, i.e. property of thermal and electrical insulation, acoustic properties, and, depending on the composition, color and smell.
As a mixture with “unsorted” fibers, liquid wood is an isotropic material, instead of the natural wood.