Reducing the moisture sensitivity of linear friction welded birch ( Betula pendula L.) wood through thermal modification

Ruponen, Jussi; Čermák, Petr; Rhême, Martin; Rautkari, Lauri (2015). Reducing the moisture sensitivity of linear friction welded birch ( Betula pendula L.) wood through thermal modification Journal of Adhesion Science and Technology, 29(22), pp. 2461-2474. Taylor & Francis 10.1080/01694243.2015.1069721

Text Reducing the moisture sensitivity of linear friction welded birch ( Betula pendula L.) wood through thermal modification.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (634kB) | Request a copy

Linear friction welding of wood is a bonding process applied to wood and during which a stiff bond line is formed by the softening and rehardening of wood components to form a composite material composed mainly of wood fibres embedded in a modified lignin matrix. Unfortunately, the bonds tend to spontaneously delaminate or lose their strength when exposed to moist conditions. Some approaches were previously applied to overcome this problem, but so far a suitable solution has not been found. This paper presents results of applying post-welding thermal modification to reduce the moisture sensitivity of welded wood. The experiments included welding of birch wood, thermal modification under superheated steam at atmospheric pressure, internal bond (IB) and tensile-shear strength testing and soaking tests. As supposed, the non-modified reference specimens performed poorly after the seven days soaking test (on average 0.33 MPa IB strength), whereas the thermally modified specimens yielded almost the same IB strength in dry and wet condition (on average e.g. 1.15 and 0.93 MPa, respectively). Such a similar load bearing capacity in very different moisture conditions was previously reported only in the case of paduk wood. Similar to the reduction of IB strength occurred during the soaking test, also delamination was observed more clearly in non-modified reference specimens (e.g. 4 vs. 0 total delaminations after seven days soaking). Therefore, the authors suggest that post-welding thermal modification could provide a suitable bond-stabilisation method against moisture, although the process parameters must be optimised in further research, for instance, to ensure scalability.

Item Type:	Journal Article (Original Article)
Division/Institute:	School of Architecture, Wood and Civil Engineering
Name:	Ruponen, Jussi; Čermák, Petr; Rhême, Martin and Rautkari, Lauri
ISSN:	0169-4243
Publisher:	Taylor & Francis
Language:	English
Submitter:	Service Account
Date Deposited:	17 Dec 2019 10:11
Last Modified:	17 Dec 2019 10:11
Publisher DOI:	10.1080/01694243.2015.1069721
ARBOR DOI:	10.24451/arbor.5866
URI:	https://arbor.bfh.ch/id/eprint/5866