Lignin

Lignin is an aromatic natural or bio-polymer. It is the natural glue that supports the tissues of most plants in the formation of cell walls. Cellulose is the main substance which makes up the cell walls and fibres of plants while lignin acts as a binder for cellulose fibres, it adds strength and stiffness contributing to the overall structural capacity as well as a defence against pests and pathogens.

Wood is the main source of lignin, accounting for about 30% of its weight, but in lesser amounts it is also a natural component of grasses and straw. Combined, it is the second most abundant class of biopolymer on Earth.

Lignin is a generic term that describes a large group of aromatic biopolymers, the chemical composition of which varies from species to species, but traditionally it is considered to be formed from the oxidative coupling of three monolignols: p-coumaryl, coniferyl, and sinapyl alcohols.

In terms of building materials, in particular wood waste, lignin can be separated from its base material by bio-bleaching, and can replace fossil-based phenols that are used as resins for plywood, oriented strand board (OSB), laminated veneer lumber (LVL), paper lamination and insulation material. It has a variety of potential applications including as a filler for thermoplastic biomacromolecules to improve mechanical properties, such as water resistance, and thermal stability.

[edit] Related articles on Designing Buildings

• Biomaterial.
• Cross-laminated timber.
• Glulam.
• Laminated veneer lumber LVL.
• Modified wood.
• Physical Properties of Wood.
• Programme for the Endorsement of Forest Certification.
• Sustainable timber.
• Testing timber.
• Types of timber.
• Types of rapidly renewable content.
• Whole life carbon assessment of timber.