Two systems of welding wood without adhesives have been developed: vibration welding and high speed rotation welding.Vibration welding used to weld two flat wood surfaces to each other. High speed rotation welding of wood dowels into wood substrates, used to join several wood specimens with everyday, inexpensive equipment. Both systems of wood-to-wood welding are based on the melting and flowing of the amorphous, cells-interconnecting polymer material in the structure of wood, mainly lignin, but also hemicelluloses. This is caused by the high temperature reached quickly at the interface, and at the interface only. This causes partial detachment, the ungluing of long wood cells, wood fibres, and the formation of a fibres entanglement network in the matrix of molten material which then solidifies. Thus, a wood cells/fibres entanglement network composite having a molten lignin polymer matrix is formed.
Source: nordiskskogforskning.orgAdded: 8 June 2006