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. 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:

BFH Zentren > BFH Zentrum Holz - Ressource und Werkstoff
Department of Architecture, Wood and Civil Engineering
Department of Architecture, Wood and Civil Engineering > Bereich Forschung & Entwicklung, Dienstleistungen und Weiterbildung
Department of Architecture, Wood and Civil Engineering > Bereich Forschung & Entwicklung, Dienstleistungen und Weiterbildung > Institut für Werkstoffe und Holztechnologie

Name:

Gfeller, Balz; Pizzi, Antonio; Zanetti, Michela; Properzi, Milena; Pichelin, Frédéric; 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:

0018-3830

Language:

English

Submitter:

Sally Haddad

Date Deposited:

22 Apr 2020 14:46

Last Modified:

22 Apr 2020 14:46

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

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