Solid wood joints by in situ welding of structural wood constituents

Gfeller, Balz; Pizzi, Antonio; Zanetti, Michela; Properzi, Milena; Pichelin, Frédéric; Lehmann, Mario; Delmotte, Luc (2004). Solid wood joints by in situ welding of structural wood constituents Holzforschung, 58(1), pp. 45-52. De Gruyter 10.1515/HF.2004.007

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Mechanicallyinduced wood flow welding, without any adhesive, is here shown to rapidly yield wood joints satisfying the relevant requirements for structural application. The mechanism of mechanicallyinduced vibrational wood flow welding is shown to be due mostly to the melting and flowing of the amorphous polymer materials interconnecting wood cells, mainly lignin, but also some hemicelluloses. This causes the partial detachment of long wood cells and wood fibres and the formation of an entanglement network in a matrix of melted material which then solidifies. Thus, it forms a wood cell/fibre entanglement network composite having a molten lignin polymer matrix. During the welding period, some of the detached wood fibres no longer held by the interconnecting material are pushed out of the joint as excess fibre. Crosslinking chemical reactions of lignin and of carbohydratederived furfural also occur. Their presence has been identified by CPMAS C-13 NMR. These reactions are, however, relatively minor contributors during the very short welding period. Their contribution increases after welding has finished, explaining why relatively longer holding times under pressure after the end of welding contribute strongly to obtaining a good bond.

Item Type:	Journal Article (Original Article)
Division/Institute:	School of Architecture, Wood and Civil Engineering School of Architecture, Wood and Civil Engineering > Institute for Materials and Wood Technology BFH Centres and strategic thematic fields > BFH Centre for Wood - Resource and Material
Name:	Gfeller, Balz; Pizzi, Antonio; Zanetti, Michela; Properzi, Milena; Pichelin, Frédéric0000-0003-3856-6707; Lehmann, Mario and Delmotte, Luc
Subjects:	Q Science > Q Science (General) T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General)
ISSN:	1437-434X
Publisher:	De Gruyter
Language:	English
Submitter:	Sally Haddad
Date Deposited:	22 Apr 2020 14:46
Last Modified:	04 Dec 2023 14:37
Publisher DOI:	10.1515/HF.2004.007
Uncontrolled Keywords:	Wood welding Wood flow Polymer melting Adhesives Lignin Joints
ARBOR DOI:	10.24451/arbor.11536
URI:	https://arbor.bfh.ch/id/eprint/11536