Tensile-shear strength studies on self-bonded 2-ply birch veneer joint manufactured and tested by applying Automated Bonding Evaluation System (ABES) hot press

Jussi Ruponen, Samuli Kimpimäki, Anti Rohumaa, Kristiina Laine, Kristoffer Segerholm, Magnus Wålinder, Lauri Rautkari, Mark Hughes

Research output: Chapter in Book/Report/Conference proceedingConference contributionScientificpeer-review

Abstract

An Automatic Bond Evaluation System (ABES) hot press was employed to manufacture a self-bonded joint between two veneers of rotary-cut birch (Betula pendula Roth). The hot-pressing conditions were 220 °C and 5.0 MPa, with press times ranging from 180 s to 600 s with 60 s intervals. Additionally, the log-soaking temperature (20 °C and 70 °C) and the veneer initial MC (6% and 11%) were varied to study the effect on the tensile-shear strength of the joints. For one set, the surface properties were altered by acetone extraction. The samples were tested at 11% MC. However, one set was partly duplicated and tested at 6% MC, to study how the testing conditions influenced the bond strength. The maximum average tensile-shear strength was 3.3 MPa, observed after 600 s hot pressing. The studies also included bond-line micromorphology analysis by applying SEM combined with a micromachining surface preparation technique based on UV excimer laser ablation. It was also indicated that longer hot-pressing times, lower veneer initial MC and a lower testing MC resulted in increased tensile-shear strength. Acetone extraction decreased the bond strength with increased standard deviation. Finally, the highest single and average strengths were observed for veneers from higher soaking temperature.

Original languageEnglish
Title of host publicationWCTE 2016 - World Conference on Timber Engineering
PublisherVienna University of Technology
ISBN (Electronic)9783903039001
Publication statusPublished - 2016
MoE publication typeA4 Article in a conference publication
EventWorld Conference on Timber Engineering - Vienna, Austria
Duration: 22 Aug 201625 Aug 2016
Conference number: 14
http://wcte2016.conf.tuwien.ac.at/home/

Conference

ConferenceWorld Conference on Timber Engineering
Abbreviated titleWCTE
CountryAustria
CityVienna
Period22/08/201625/08/2016
Internet address

Keywords

  • ABES
  • Birch
  • Laser ablation
  • Self-bonding
  • SEM
  • Soaking temperature
  • Tensile-shear strength
  • Veneer

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